Hach DR2010 User manual

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49300-22

DR/2010

SPECTROPHOTOMETER

PROCEDURES MANUAL

jnb/dk 10/00 rev2

TABLE OF CONTENTS

INTRODUCTION .............................................................................................................. 11

Sample Procedure Explained .................................................................................................. 13

SECTION I CHEMICAL ANALYSIS INFORMATION......................................... 17

Abbreviations .......................................................................................................................... 17

Converting Chemical Species ................................................................................................. 18

Hardness Conversion ........................................................................................................... 19

Dissolved Oxygen................................................................................................................ 20

Sample Collection, Preservation and Storage ...................................................................... 22

Collecting Water Samples ................................................................................................ 25

Acid Washing Bottles....................................................................................................... 25

Correcting for Volume Additions ........................................................................................ 26

Boiling Aids ......................................................................................................................... 26

Sample Filtration.................................................................................................................. 27

Temperature Considerations ................................................................................................ 29

Sample Dilution Techniques................................................................................................ 29

Sample Dilution and Interfering Substances .................................................................... 30

Using Pipets and Graduated Cylinders ................................................................................ 31

Using the TenSette Pipet...................................................................................................... 32

Operating the TenSette Pipet............................................................................................ 32

Mixing Water Samples ........................................................................................................ 33

Using Sample Cells.............................................................................................................. 35

Orientation of Sample Cells.............................................................................................. 35

Care of Hach 1-inch Sample Cells.................................................................................... 35

Cleaning Sample Cells...................................................................................................... 35

Sample Cell Matching ...................................................................................................... 36

Volume Measurement Accuracy ...................................................................................... 37

Using AccuVac Ampuls ...................................................................................................... 37

Using Reagent Powder Pillows............................................................................................ 38

Using PermaChem Pillows .................................................................................................. 39

Using the Pour-Thru Cell..................................................................................................... 39

Reagent and Standard Stability............................................................................................ 40

Interferences............................................................................................................................ 41

pH Interference .................................................................................................................... 41

Accuracy and Precision........................................................................................................... 42

Standard Additions............................................................................................................... 43

TABLE OF CONTENTS, continued

Method Performance............................................................................................................... 50

Estimated Detection Limit................................................................................................... 50

Precision .............................................................................................................................. 53

Estimating Precision......................................................................................................... 53

Selecting the Best Wavelength ............................................................................................... 54

Adapting HACH Procedures to Other Spectrophotometers................................................... 57

Preparing a Calibration Curve............................................................................................. 57

%T Versus Concentration Calibration ............................................................................. 57

Absorbance Versus Concentration Calibration ................................................................ 59

USEPA Approved and Accepted Definitions ......................................................................... 60

SECTION II SAMPLE PRETREATMENT ............................................................... 61

Digestion................................................................................................................................. 61

EPA Mild Digestion with Hot Plate for Metals Analysis Only........................................... 61

EPA Vigorous Digestion with Hot Plate for Metals Analysis Only ................................... 62

General Digesdahl Digestion (Not USEPA accepted) ........................................................ 63

Distillation .............................................................................................................................. 63

SECTION III WASTE MANAGEMENT AND SAFETY........................................ 65

Waste Management................................................................................................................. 65

Waste Minimization ............................................................................................................ 65

Regulatory Overview........................................................................................................... 65

Hazardous Waste Definition................................................................................................ 66

Characteristic Hazardous Waste Codes ............................................................................... 67

How to Determine if Waste is Hazardous ........................................................................... 67

Examples of Hazardous Waste............................................................................................ 68

Hazardous Waste Disposal.................................................................................................. 68

Management of Specific Wastes ......................................................................................... 69

Special Considerations for Cyanide Containing Materials .............................................. 69

Resources............................................................................................................................. 70

Material Safety Data Sheets.................................................................................................... 71

How to Obtain an MSDS..................................................................................................... 71

Sections of an MSDS........................................................................................................... 72

TABLE OF CONTENTS, continued

Safety....................................................................................................................................... 74

Material Safety Data Sheet .................................................................................................. 74

Reading Labels Carefully .................................................................................................... 74

Protective Equipment........................................................................................................... 75

First Aid Equipment and Supplies ....................................................................................... 75

General Safety Rules............................................................................................................ 75

OSHA Chemical Hygiene Plan............................................................................................ 76

SECTION IV PROCEDURES ........................................................................................ 77

ALUMINUM, Aluminon Method........................................................................................... 79

ALUMINUM, Eriochrome Cyanine R Method...................................................................... 87

ARSENIC, Silver Diethyldithiocarbamate Method ................................................................ 95

BARIUM, Turbidimetric Method ......................................................................................... 103

BENZOTRIAZOLE, UV Photolysis Method ....................................................................... 111

BORON, Carmine Method.................................................................................................... 117

BORON, Low Range, Azomethine-H Method .................................................................... 121

BROMINE, DPD Method..................................................................................................... 129

CADMIUM, Dithizone Method............................................................................................ 137

CHLORIDE, Mercuric Thiocyanate Method........................................................................ 145

CHLORINE, FREE, DPD Method ....................................................................................... 149

CHLORINE, FREE, DPD Rapid Liquid Method ................................................................ 157

CHLORINE, FREE, HIGH RANGE, DPD Method............................................................. 163

CHLORINE, FREE, DPD Test ‘N Tube™ Method ............................................................. 169

CHLORINE, TOTAL, Ultra Low Range, DPD Method ...................................................... 175

CHLORINE, TOTAL, Ultra Low Range, DPD Method ..................................................... 183

CHLORINE, TOTAL, DPD Method .................................................................................... 191

CHLORINE, TOTAL, DPD Rapid Liquid Method ............................................................. 199

CHLORINE, TOTAL, HIGH RANGE, DPD Method ........................................................ 205

CHLORINE, TOTAL, DPD Test ‘N Tube™ Method.......................................................... 211

CHLORINE DIOXIDE, LR, Chlorophenol Red Method..................................................... 217

CHLORINE DIOXIDE, HR, Direct Reading Method.......................................................... 221

CHLORINE DIOXIDE, DPD Method.................................................................................. 223

TABLE OF CONTENTS, continued

CHROMIUM, HEXAVALENT, 1,5-Diphenylcarbohydrazide Method.............................. 233

CHROMIUM, TOTAL, Alkaline Hypobromite Oxidation Method ................................... 239

COBALT, 1-(2-Pyridylazo)-2-Naphthol (PAN) Method ..................................................... 245

COLOR, NCASI 253, Platinum-Cobalt Method.................................................................. 249

COLOR, TRUE AND APPARENT, APHA Platinum-Cobalt Standard Method ............... 253

COPPER, Bicinchoninate Method........................................................................................ 257

COPPER, Porphyrin Method................................................................................................ 265

COPPER, AUTOCATALYTIC, Colorimetric Method........................................................ 271

CYANIDE, Pyridine-Pyrazalone Method ............................................................................ 277

CYANURIC ACID, Turbidimetric Method......................................................................... 287

FLUORIDE, SPADNS Method............................................................................................ 291

FORMALDEHYDE, MBTH Method .................................................................................. 299

HARDNESS, Calcium and Magnesium; Calmagite Colorimetric Method.......................... 303

HARDNESS, TOTAL, Ultra Low Range, Calcium and Magnesium Chlorophosphonazo

Colorimetric Method ......................................................................................................... 309

HARDNESS, TOTAL, Ultra Low Range, Calcium and Magnesium; Chlorophosphonazo

Rapid Liquid Method ........................................................................................................ 313

HYDRAZINE, p-Dimethylaminobenzaldehyde Method ..................................................... 319

IODINE, DPD Method ......................................................................................................... 325

IRON, FerroZine Method ..................................................................................................... 333

IRON, FerroZine Rapid Liquid Method............................................................................... 339

IRON, FERROUS, 1,10 Phenanthroline Method................................................................. 345

IRON, TOTAL, FerroMo™ Method.................................................................................... 349

IRON, TOTAL, FerroVer Method ....................................................................................... 353

IRON, TOTAL, TPTZ Method............................................................................................. 361

LEAD, Dithizone Method..................................................................................................... 369

LEAD, LeadTrak™ Fast Column Extraction Method.......................................................... 377

MANGANESE, HR, Periodate Oxidation Method .............................................................. 387

MANGANESE, LR, PAN Method....................................................................................... 391

MERCURY, Cold Vapor Mercury Concentration Method.................................................. 397

MOLYBDENUM, MOLYBDATE, HR, Mercaptoacetic Acid Method.............................. 413

MOLYBDENUM, MOLYBDATE, LR, Ternary Complex Method ................................... 421

TABLE OF CONTENTS, continued

NICKEL, 1-(2 Pyridylazo)-2-Naphthol (PAN) Method ....................................................... 427

NICKEL, Heptoxime Method............................................................................................... 433

NICKEL, AUTOCATALYTIC, Photometric Method ......................................................... 439

NITRATE, LR, Cadmium Reduction Method...................................................................... 443

NITRATE, MR, Cadmium Reduction Method..................................................................... 449

NITRATE, HR, Cadmium Reduction Method...................................................................... 457

NITRATE, HR, Chromotropic Acid Method, Test ‘N Tube™ ............................................ 465

NITRITE, LR, Diazotization Method ................................................................................... 471

NITRITE, LR, Diazotization, NED Rapid Liquid Method................................................... 477

NITRITE, LR, Test ‘N Tube, Diazotization (Chromotropic Acid) Method......................... 483

NITRITE, HR, Ferrous Sulfate Method................................................................................ 487

NITROGEN, TOTAL, HR, Test ’N Tube™, TNT Persulfate Digestion Method................ 491

NITROGEN, AMMONIA, Nessler Method......................................................................... 499

NITROGEN, AMMONIA, Salicylate Method ..................................................................... 505

NITROGEN, AMMONIA, High Range, Test ’N Tube, Salicylate Method......................... 511

NITROGEN, AMMONIA, Low Range Test ‘N Tube, Salicylate Method .......................... 517

NITROGEN, MONOCHLORAMINE and FREE AMMONIA, Salicylate Method............ 523

NITROGEN, TOTAL, Test ’N Tube, TNT Persulfate Digestion Method ........................... 531

NITROGEN, TOTAL KJELDAHL, Nessler Method .......................................................... 539

NITROGEN, TOTAL INORGANIC, Test ‘N Tube, Titanium Trichloride Reduction ....... 549

ORGANIC CARBON, TOTAL, Low Range, Direct Method.............................................. 557

ORGANIC CARBON, TOTAL, High Range, Direct Method ............................................. 565

ORGANIC MATTER, Dichromate Method......................................................................... 573

OXYGEN, DISSOLVED, LR, Indigo Carmine Method...................................................... 579

OXYGEN, DISSOLVED, HR, HRDO Method ................................................................... 583

OXYGEN, DISSOLVED, SHR, Super High Range Method............................................... 587

OXYGEN DEMAND, CHEMICAL, Reactor Digestion Method........................................ 591

Colorimetric Determination, 0 to 150 mg/L COD ............................................................. 593

Colorimetric Determination, 0 to 1,500 and 0 to 15,000 mg/L COD................................ 595

OXYGEN DEMAND, CHEMICAL (COD), Dichromate Reflux Method .......................... 601

Colorimetric Determination............................................................................................... 603

Buret Titration.................................................................................................................... 605

OXYGEN DEMAND, CHEMICAL, Manganese III Digestion Method ............................. 611

TABLE OF CONTENTS, continued

OXYGEN DEMAND, CHEMICAL, Manganese III Digestion Method............................. 615

OXYGEN SCAVENGERS, Iron Reduction Method for Oxygen Scavengers .................... 623

OZONE, Indigo Method....................................................................................................... 627

PALLADIUM, N,N'-Dimethyldithiooxamide Method ........................................................ 631

PCB IN SOIL, Immunoassay Method.................................................................................. 635

PHENOLS, 4-Aminoantipyrine Method .............................................................................. 645

PHOSPHONATES, Persulfate UV Oxidation Method........................................................ 651

PHOSPHORUS, REACTIVE, PhosVer 3 Method, Test ’N Tube Procedure ...................... 657

PHOSPHORUS, REACTIVE, (Also called Orthophosphate) Amino Acid Method ........... 663

PHOSPHORUS, REACTIVE, (Also called Orthophosphate) Molybdovanadate Method.. 669

PHOSPHORUS, REACTIVE, PhosVer 3 (Ascorbic Acid) Method.................................... 677

PHOSPHORUS, REACTIVE, LOW RANGE, Ascorbic Acid Rapid Liquid Method........ 685

PHOSPHORUS, REACTIVE, HIGH RANGE, Molybdovanadate Rapid Liquid Method . 691

PHOSPHORUS, REACTIVE, HR, Molybdovanadate Method, Test ’N Tube™ ............... 697

PHOSPHORUS, TOTAL, Acid Persulfate Digestion Method............................................. 703

PHOSPHORUS, TOTAL, PhosVer 3 with Acid Persulfate Digestion Test ‘N Tube.......... 707

PHOSPHORUS, TOTAL, HR, Molybdovanadate Method with Acid Persulfate Digestion,

Test ’N Tube™.................................................................................................................. 715

PHOSPHORUS, ACID HYDROLYZABLE, PhosVer3 with Acid Hydrolysis,................. 723

Test ’N Tube...................................................................................................................... 723

PHOSPHORUS, ACID HYDROLYZABLE, Hydrolysis to Orthophosphate Method........ 729

POLYACRYLIC ACID, Absorption-Colorimetric Method ................................................ 733

POTASSIUM, Tetraphenylborate Method........................................................................... 741

QUATERNARY AMMONIUM COMPOUNDS, Direct Binary Complex Method ........... 747

SELENIUM, Diaminobenzidine Method ............................................................................. 753

SILICA, HR, Silicomolybdate Method ................................................................................ 761

SILICA, LR, Heteropoly Blue Method ................................................................................ 767

SILICA, ULTRA LOW RANGE, Heteropoly Blue Method ............................................... 773

SILICA, ULR, Heteropoly Blue Rapid Liquid Method ....................................................... 779

SILVER, Colorimetric Method............................................................................................. 785

SODIUM CHROMATE, Direct Colorimetric Method ........................................................ 791

TABLE OF CONTENTS, continued

SULFATE, SulfaVer 4 Method ............................................................................................ 795

SULFIDE, Methylene Blue Method* ................................................................................... 803

SURFACTANTS, ANIONIC, Crystal Violet Method.......................................................... 807

SUSPENDED SOLIDS, Photometric Method...................................................................... 811

TANNIN AND LIGNIN, Tyrosine Method ......................................................................... 815

THM Plus™: Trihalomethanes, ........................................................................................... 819

TOXTRAK TOXICITY TEST, Colorimetric Method ......................................................... 829

TPH IN SOIL, Immunoassay Method................................................................................... 835

TPH IN WATER, Immunoassay Method ............................................................................. 845

TURBIDITY, Attenuated Radiation Method (direct reading) .............................................. 853

VOLATILE ACIDS, Esterification Method......................................................................... 857

ZINC, Zincon Method........................................................................................................... 861

SECTION V GENERAL INFORMATION ............................................................... 867

HOW TO ORDER............................................................................................................ 869

REPAIR SERVICE .......................................................................................................... 870

WARRANTY ..................................................................................................................... 871

INTRODUCTION

This manual is divided into five sections:

Section I Chemical Analysis Information

This section applies to all the procedures. It provides background information and reference/review material for the technician or chemist. Commonly used techniques are explained in detail.

Section II Sample Pretreatment

This section provides a brief overview of sample pretreatment and three digestion procedures. Two are USEPA digestions. The Hach Digesdahl method is also included.

Section III Waste Management and Safety

Section 3 includes information an waste management, regulations, waste disposal and resources on waste management. The Safety portion covers reading an MSDS and general safety guidelines.

Section IV Procedures

Section 4 contains step-by-step illustrated instructions for measuring over 120 parameters. The steps also include helpful notes. Each procedure contains information on sample collection, storage and preservation, accuracy checks, possible interferences, summary of method and a list of the reagents and apparatus necessary to run the test.

Section V Ordering Information

This section provides information needed for ordering, shipping, return of items and Hach trademarks.

Before attempting the analysis procedures the analyst should read the instrument manual to learn about the spectrophotometer’s features and operation.

INTRODUCTION, continued

Hach Company Trademarks

AccuGrow

AccuVac

AccuVer™

AccuVial™

Add-A-Test™

AgriTrak™

AluVer

AmVer™

APA 6000™

AquaChek™

AquaTrend

BariVer

BODTrak™

BoroTrace™

BoroVer

C. Moore Green™

CA 610™

CalVer

ChromaVer

ColorQuik

CoolTrak

CuVer

CyaniVer

Digesdahl

DithiVer

Dr. F. Fluent™

Dr. H. Tueau™

DR/Check™

EC 310™

FerroMo

FerroVer

FerroZine

FilterTrak™ 660

Formula 2533™

Formula 2589™

Gelex

H2O University™

H2OU™

Hach Logo

Hach One

Hach Oval

Hach.com™

HachLink™

Hawkeye The Hach Guy™

HexaVer

HgEx™

HydraVer

ICE-PIC™

IncuTrol

Just Add Water™

LeadTrak

M-ColiBlue24

ManVer

MolyVer

Mug-O-Meter

NetSketcher™

NitraVer

NitriVer

NTrak

OASIS™

On Site Analysis. Results You Can Trust

OptiQuant™

OriFlow™

OxyVer™

PathoScreen™

PbEx

PermaChem

PhosVer

Pocket Colorimeter™

Pocket Pal™

Pocket Turbidimeter™

Pond In Pillow™

ion

√

™

PourRite

PrepTab™

ProNetic™

Pump Colorimeter™

QuanTab

Rapid Liquid™

RapidSilver™

Ratio™

RoVer

sens

Simply Accurate

SINGLET™

SofChek™

SoilSYS™

SP 510™

Spec ™

StablCal

StannaVer

SteriChek™

StillVer

SulfaVer

Surface Scatter

TanniVer

TenSette

Test ‘N Tube™

TestYES!

TitraStir

TitraVer

ToxTrak™

UniVer

VIScreen™

Voluette

WasteAway™

ZincoVer

Sample Procedure Explained

Sample Procedure Explained, continued

SECTION I CHEMICAL ANALYSIS INFORMATION

Abbreviations

The following abbreviations are used throughout the text of the procedure section:

Abbrev-

iation

°C degree(s) Celsius (Centigrade) HR high range

°F degree(s) Fahrenheit kg/ha kilograms per hectare

ACS

APHA Standard Methods

AV AccuVac MR medium range

Bicn bicinchoninate NIPDWR

CFR Code of Federal Regulations NPDES

conc concentrated P phosphorus

DB dropping bottle PCB Poly chlorinated biphenyl

EDL Estimated detection limit PV PhosVer

F&T free and total RL Rapid Liquid™

FAU

FM FerroMo

FV FerroVer

FZ FerroZine

gr/gal grains per gallon (1 gr/gal = 17.12 mg/L) USEPA

American Chemical Society reagent grade purity

Standard Methods for the Examination of Water and Wastewater, published jointly by

the American Public Health Association (APHA), the American Water Works Association (AWWA), and the Water Environment Federation (WEF). Order from Hach requesting Cat. No. 22708-00 or from the Publication Office of the American Public Health Association. This book is the standard reference work for water analysis. Many procedures contained in this manual are based on Standard Methods.

Formazin Attenuation Units. Turbidity unit of measure based on a Formazin stock suspension.

g grams ULR Ultra low range

Definition

Abbrev-

iation

l or L

lbs/Ac pounds per acre

LR low range

MDL Method detection limit

MDB marked dropping bottle

mg/L milligrams per liter (ppm)

µg/L micrograms per liter (ppb)

ml or mL

SCDB self-contained dropping bottle

TNT Te s t ‘N Tube™

TPH Total petroleum hydrocarbons

TPTZ (2,4,6-Tri-(2-Pyridyl)-1,3,5-Triazine)

Liter. Volume equal to one cubic decimeter (dm

(milliliter)-approximately the same as a cubic centimeter (cc) or 1/1000 of a liter. Also known as a “cc”.

National Interim Primary Drinking Water Regulations

National Pollutant Discharge Elimination System

United States Environmental Protection Agency

Definition

)

SECTION I, continued

Converting Chemical Species

Species conversion factors for many commonly used substances are preprogrammed into the DR/2010 (see Table 1). Conversions are method specific and are viewable after taking the reading by pressing

Table 1 Conversion Factors

To Convert From... To... Multiply By... Conversion used in program #

mg/L Al mg/L Al2O

mg/L B mg/L H

mg/L Ca-CaCO

mg/L CaCO

3BO3

mg/L Ca 0.4004 220

mg/L Ca 0.4004 227

mg/L Mg 0.2428 227

1.8895 9, 10

5.7 45

µg/L Carbo. µg/L Hydro. 1.92 182

µg/L Carbo. µg/L ISA 2.69 182

µg/L Carbo. µg/L MEKO 3.15 182

mg/L Cr

mg/L Mg-CaCO

mg/L CrO

mg/L Na2CrO

mg/L Mg 0.2428 225

mg/L Mn mg/L KMnO

mg/L Mn mg/L MnO

mg/L Mo

mg/L MoO

mg/L Na2MoO

mg/L N mg/L NH

mg/L N mg/L NO

mg/L Na

mg/L NH

mg/L NO

µg/L NO

mg/L NO

µg/L NO

mg/L NO

mg/L PO

µg/L PO

mg/L PO

µg/L PO

mg/L SiO

µg/L SiO

CrO

Cl-N mg/L Cl

Cl-N mg/L NH2Cl 3.6750 386

-N mg/L NH

-N mg/L NaNO

-N µg/L NaNO

-N mg/L NO

-N µg/L NO

-N mg/L NO

mg/L Cr

mg/L CrO

mg/L NaNO

mg/L NO

mg/L P 0.3261 480, 482, 485, 490, 492, 535

µg/L P 0.3261 488

mg/L P2O

µg/L P2O

mg/L Si 0.4674 651, 656

µg/L Si 0.4674 645

-N 0.3045 373

2.231 90, 95

3.115 90, 95

2.876 290, 295

2.165 290, 295

1.667 315, 320, 322

2.146 315, 320, 322

1.216 342, 343, 346, 347, 348

4.427 346, 347, 348

0.321 670

0.72 670

5.0623 386

1.216 380, 385, 387

1.288 380, 385, 387

1.5 373

4.926 345, 371, 375

4.926 376

3.284 345, 371, 375

3.284 376

4.427 344, 351, 353, 355, 359, 361

0.7473 480, 482, 485, 490, 492, 535

0.7473 488

CONC.

SECTION I, continued

Hardness Conversion

Table 2 lists the factors for converting one unit of measure for hardness to another unit of measure. For example, to convert mg/L CaCO parts/100,000 CaO, multiply the value in mg/L x 0.056.

Table 2 Hardness Conversion Factors

Units of

Measure

mg/L

CaCO

English

British

gr/gal

(Imperial)

mg/L

CaCO

1.0 0.07 0.058 0.1 0.056 0.02 5.6x10

14.3 1.0 0.83 1.43 0.83 0.286 8.0x10

American

gr/gal (US)

CaCO

gr/gal

CaCO

US gr/gal

CaCO

Fr. p/

17.1 1.2 1.0 1.72 0.96 0.343 9.66x10

10.0 0.7 0.58 1.0 0.56 0.2 5.6x10

100,000

CaCO

Ger. p/

17.9 1.25 1.04 1.79 1.0 0.358 1x10

100,000

CaO

meq/L 50.0 3.5 2.9 5.0 2.8 1.0 2.8x10

g/L CaO 1790.0 125.0 104.2 179.0 100.0 35.8 1.0 0.112

lbs./cu ft

CaCO

16,100.0 1,123.0 935.0 1,610.0 900.0 321.0 9.0 1.0

1 ‘epm/L, or ‘mval/L’

Note: 1 meq/L = 1N/1000

French

parts/

100,000

CaCO

German

Parts/

100,000

CaO

meq/L

g/L CaO

to German

lbs./cu ft

-4

6.23x10

-3

1.07x10

-3

6.23x10

-2

1.12x10

-2

3.11x10

CaCO

8.9x10

-5

-4

-3

-4

-3

-2

SECTION I, continued

Dissolved Oxygen

Table 3 lists the mg/L dissolved oxygen in water at saturation for various temperatures and atmospheric pressures. The table was formulated in a laboratory using pure water. The values given are only approximations for estimating the oxygen content of a particular body of surface water.

Table 3 Dissolved Oxygen Saturation in Water

Pressure in Millimeters and Inches Hg

775 760 750 725 700 675 650 625

Temp inches

°F °C 30.51 29.92 29.53 28.45 27.56 26.57 25.59 24.61

32.0 0 14.9 14.6 14.4 13.9 13.5 12.9 12.5 12.0

33.8 1 14.5 14.2 14.1 13.6 13.1 12.6 12.2 11.7

35.6 2 14.1 13.9 13.7 13.2 12.9 12.3 11.8 11.4

37.4 3 13.8 13.5 13.3 12.9 12.4 12.0 11.5 11.1

39.2 4 13.4 13.2 13.0 12.5 12.1 11.7 11.2 10.8

41.0 5 13.1 12.8 12.6 12.2 11.8 11.4 10.9 10.5

42.8 6 12.7 12.5 12.3 11.9 11.5 11.1 10.7 10.3

44.6 7 12.4 12.2 12.0 11.6 11.2 10.8 10.4 10.0

46.4 8 12.1 11.9 11.7 11.3 10.9 10.5 10.1 9.8

48.2 9 11.8 11.6 11.5 11.1 10.7 10.3 9.9 9.5

50.0 10 11.6 11.3 11.2 10.8 10.4 10.1 9.7 9.3

51.8 11 11.3 11.1 10.9 10.6 10.2 9.8 9.5 9.1

53.6 12 11.1 10.8 10.7 10.3 10.0 9.6 9.2 8.9

55.4 13 10.8 10.6 10.5 10.1 9.8 9.4 9.1 8.7

57.2 14 10.6 10.4 10.2 9.9 9.5 9.2 8.9 8.5

59.0 15 10.4 10.2 10.0 9.7 9.3 9.0 8.7 8.3

60.8 16 10.1 9.9 9.8 9.5 9.1 8.8 8.5 8.1

62.6 17 9.9 9.7 9.6 9.3 9.0 8.6 8.3 8.0

64.4 18 9.7 9.5 9.4 9.1 8.8 8.4 8.1 7.8

66.2 19 9.5 9.3 9.2 8.9 8.6 8.3 8.0 7.6

68.0 20 9.3 9.2 9.1 8.7 8.4 8.1 7.8 7.5

69.8 21 9.2 9.0 8.9 8.6 8.3 8.0 7.7 7.4

71.6 22 9.0 8.8 8.7 8.4 8.1 7.8 7.5 7.2

73.4 23 8.8 8.7 8.5 8.2 8.0 7.7 7.4 7.1

75.2 24 8.7 8.5 8.4 8.1 7.8 7.5 7.2 7.0

77.0 25 8.5 8.4 8.3 8.0 7.7 7.4 7.1 6.8

78.8 26 8.4 8.2 8.1 7.8 7.6 7.3 7.0 6.7

80.6 27 8.2 8.1 8.0 7.7 7.4 7.1 6.9 6.6

SECTION I, continued

Table 3 Dissolved Oxygen Saturation in Water (continued)

Pressure in Millimeters and Inches Hg

775 760 750 725 700 675 650 625

Temp inches

°F °C 30.51 29.92 29.53 28.45 27.56 26.57 25.59 24.61

82.4 28 8.1 7.9 7.8 7.6 7.3 7.0 6.7 6.5

84.2 29 7.9 7.8 7.7 7.4 7.2 6.9 6.6 6.4

86.0 30 7.8 7.7 7.6 7.3 7.0 6.8 6.5 6.2

87.8 31 7.7 7.5 7.4 7.2 6.9 6.7 6.4 6.1

89.6 32 7.6 7.4 7.3 7.0 6.8 6.6 6.3 6.0

91.4 33 7.4 7.3 7.2 6.9 6.7 6.4 6.2 5.9

93.2 34 7.3 7.2 7.1 6.8 6.6 6.3 6.1 5.8

95.0 35 7.2 7.1 7.0 6.7 6.5 6.2 6.0 5.7

96.8 36 7.1 7.0 6.9 6.6 6.4 6.1 5.9 5.6

98.6 37 7.0 6.8 6.7 6.5 6.3 6.0 5.8 5.6

100.4 38 6.9 6.7 6.6 6.4 6.2 5.9 5.7 5.5

102.2 39 6.8 6.6 6.5 6.3 6.1 5.8 5.6 5.4

104.0 40 6.7 6.5 6.4 6.2 6.0 5.7 5.5 5.3

105.8 41 6.6 6.4 6.3 6.1 5.9 5.6 5.4 5.2

107.6 42 6.5 6.3 6.2 6.0 5.8 5.6 5.3 5.1

109.4 43 6.4 6.2 6.1 5.9 5.7 5.5 5.2 5.0

111.2 44 6.3 6.1 6.0 5.8 5.6 5.4 5.2 4.9

113.0 45 6.2 6.0 5.9 5.7 5.5 5.3 5.1 4.8

114.8 46 6.1 5.9 5.9 5.6 5.4 5.2 5.4 4.8

116.6 47 6.0 5.9 5.8 5.6 5.3 5.1 4.8 4.7

118.4 48 5.9 5.8 5.7 5.5 5.3 5.0 4.8 4.6

120.2 49 5.8 5.7 5.6 5.4 5.2 5.0 4.7 4.5

122.0 50 5.7 5.6 5.5 5.3 5.1 4.9 4.7 4.4

SECTION I, continued

Sample Collection, Preservation and Storage

Correct sampling and storage are critical for accurate testing. For greatest accuracy, thoroughly clean sampling devices and containers to prevent carryover from previous samples. Preserve the sample properly; each procedure has information about sample preservation.

• The least expensive containers are polypropylene or polyethylene.

• The best and most expensive containers are quartz or PTFE

(polytetrafluoroethylene, Teflon).

• Avoid soft glass containers for metals in the

microgram-per-liter range.

• Store samples for silver determination in light absorbing containers,

such as amber bottles.

Avoid contaminating the sample with metals from containers, distilled water or membrane filters. Thoroughly clean sample containers as described under Acid Washing Bottles.

Preservation slows the chemical and biological changes that continue after collection. These changes may change the amount of a chemical species available for analysis. Normally, analyze the samples as soon as possible after collection, especially when the analyte concentration is expected to be low. This also reduces the chance for error and minimizes labor.

Preservation methods include pH control, chemical addition, refrigeration and freezing. Table 4 gives the recommended preservation for various substances. It also includes suggested types of containers and the maximum recommended holding times for properly preserved samples.

Preserve aluminum, cadmium, chromium, cobalt, copper, iron, lead, nickel, potassium, silver and zinc samples for at least 24 hours by adding one Nitric Acid Solution Pillow 1:1 (Cat. No. 2540-98) per liter of sample. Check the pH with pH indicator paper or a pH meter to assure the pH is 2 or less. Add additional pillows if necessary. Adjust the sample pH prior to analysis by adding an equal number of Sodium Carbonate Anhydrous Powder Pillows (Cat. No. 179-98). Or raise the pH to 4.5 with Sodium Hydroxide Standard Solution, 1 N or 5 N.

SECTION I, continued

Table 4 Required Containers, Preservation Techniques and Holding Times

Parameter No./Name Container

Preservation

3,4

Maximum

Holding Time

Table 1A - Bacterial Tests

1-4. Coliform, fecal and total P,G Cool, 4°C, 0.008%, Na

5. Fecal streptococci P,G Cool, 4°C, 0.008%, Na

2S2O3

6 hours

Table 1B - Inorganic Tests

1. Acidity P, G Cool, 4°C 14 days

2. Alkalinity P, G Cool, 4°C 14 days

4. Ammonia P, G Cool, 4°C, H

9. Biochemical oxygen demand

P, G Cool, 4°C 48 hours

to pH<2 28 days

2SO4

(BOD)

10. Boron P, PFTE or quartz HNO

to pH<2 6 months

11. Bromide P, G None required 28 days

14. Biochemical oxygen demand,

P, G Cool, 4°C 48 hours

carbonaceous

15. Chemical oxygen demand P, G Cool, 4°C, H

to pH<2 28 days

2SO4

16. Chloride P, G None required 28 days

17. Chlorine, total residual P, G None required Analyze immediately

21. Color P, G Cool, 4°C 48 hours

23-24. Cyanide, total and amenable to chlorination

P, G Cool, 4°C, NaOH to pH>12, 0.6 g

ascorbic acid

14 days

25. Fluoride P None required 28 days

27. Hardness P, G HNO

to pH<2, H2SO4 to pH<2 6 months

28. Hydrogen ion (pH) P, G None required Analyze immediately

31, 43. Kjeldahl and organic

P, G Cool 4°C, H

to pH<2 28 days

2SO4

nitrogen

Metals

18. Chromium VI P, G Cool, 4°C 24 hours

35. Mercury P, G HNO

to pH<2 28 days

Metals, except boron, chromium VI and mercury: 3, 5-8, 12, 13, 19, 20, 22, 26, 29, 30, 32-34, 36, 37, 45, 47, 51, 52, 58-60, 62, 63, 70-72, 74,

P, G HNO

to pH<2 6 months

38. Nitrate P, G Cool, 4°C 48 hours

39. Nitrate-nitrite P, G Cool 4°C, H

to pH<2 28 days

2SO4

40. Nitrite P, G Cool, 4°C 48 hours

41. Oil and grease G Cool, 4°C, HCl or H

42. Organic Carbon

P, G Cool, 4°C, HCl or H

to pH<2

3PO4

to pH<2 28 days

2SO4

SO4 or

28 days

44. Orthophosphate P, G Filter immediately; Cool, 4°C 48 hours

46a. Oxygen, dissolved probe G Bottle and top None required Analyze immediately

46b. Oxygen, dissolved, Winkler Do Fix on site and store in dark 8 hours

48. Phenols G only Cool 4°C, H

to pH<2 28 days

2SO4

SECTION I, continued

Table 4 Required Containers, Preservation Techniques and Holding Times1 (continued)

Parameter No./Name Container

49. Phosphorus, elemental G Cool, 4°C 48 hours

50. Phosphorus, total P, G Cool, 4°C, H

53. Residue, total P, G Cool, 4°C7 days

54. Residue, filterable P, G Cool, 4°C7 days

55. Residue, Nonfilterable (TSS) P, G Cool, 4°C7 days

56. Residue, Settleable P, G Cool, 4°C 48 hours

57. Residue, volatile P, G Cool, 4°C7 days

61. Silica P, PFTE or quartz Cool, 4°C 28 days

64. Specific conductance P, G Cool, 4°C 28 days

65. Sulfate P, G Cool, 4°C 28 days

66. Sulfide

67. Sulfite P, G none required Analyze immediately

68. Surfactants P, G Cool, 4°C 48 hours

69. Temperature P, G None required Analyze immediately

73. Turbidity P, G Cool, 4°C 48 hours

1 This table was adapted from Table II published in the Federal Register, July 1, 1997, 40 CFR, Part 136.3,

pages 26-27. Organic tests are not included. 2 Polyethylene (P) or glass (G). 3 Sample preservation should be performed immediately upon sample collection. For composite chemical samples

each aliquot should be preserved at the time of collection. When use of an automated sampler makes it impossible

to preserve each aliquot, then chemical samples may be preserved by maintaining at 4°C until compositing and

sample splitting is completed. 4 When any sample is to be shipped by common carrier or sent through United States Mails, it must comply with the

Department of Transportation Hazardous Material Regulations (49 CFR Part 172). The person offering such

material for transportation is responsible for ensuring such compliance. For the preservation requirements of Table

II, the Office of Hazardous Materials, Materials Transportation Bureau, Department of Transportation has

determined that the Hazardous Materials Regulations do not apply to the following materials: Hydrochloric acid

(HCl) in water solutions at concentrations of 0.04% by weight or less (pH about 1.96 or greater); Nitric acid (HNO

in water solutions at concentrations of 0.15% by weight or less (pH about 1.62 or greater); Sulfuric acid (H

water solutions at concentrations of 0.35% by weight or less (pH about 1.15 or greater); and Sodium hydroxide

(NaOH) in water solutions at concentrations of 0.080% by weight or less (pH about 12.30 or less). 5 Samples should be analyzed as soon as possible after collection. The times listed are the maximum times that

samples may be held before analysis and still be considered valid. Samples may be held for longer periods only if

the permitee, or monitoring laboratory, has data on file to show that the specific types of samples under study are

stable for the longer time, and has received a variance from the Regional Administer under §136.3(e). Some

samples may not be stable for the maximum time period given in the table. A permitee, or monitoring laboratory, is

obligated to hold the sample for a shorter time if knowledge exists to show that this is necessary to maintain sample

stability. See §136.3(e) for details. The term “analyze immediately” usually means within 15 minutes or less after

sample collection. 6 Should only be used in the presence of residual chlorine. 7 Maximum holding time is 24 hours when sulfide is present. Optionally all samples may be tested with lead acetate

paper before pH adjustments in order to determine if sulfide is present. If sulfide is present, it can be removed by the

addition of cadmium nitrate powder until a negative spot test is obtained. The sample is filtered and then NaOH is

added to pH 12. 8 Samples should be filtered immediately on-site before adding preservative for dissolved metals. 9 Numbers refer to parameter number in 40 CFR, Part 136.3, Table 1B.

P, G Cool 4°C, add zinc acetate plus

Preservation

sodium hydroxide to pH>9

3,4

to pH<2 28 days

2SO4

Maximum

Holding Time

7 days

2SO4

) in

)

SECTION I, continued

Collecting Water Samples

Obtain the best sample by careful collection. In general, collect samples near the center of the vessel or duct and below the surface. Use only clean containers (bottles, beakers). Rinse the container several times first with the water to be sampled.

Take samples as close as possible to the source of the supply. This lessens the influence the distribution system has on the sample. Let the water run long enough to flush the system. Fill sample containers slowly with a gentle stream to avoid turbulence and air bubbles. Collect water samples from wells after the pump has run long enough to deliver water representative of the ground water feeding the well.

It is hard to obtain a truly representative sample when collecting surface water samples. Obtain best results by testing several samples. Use samples taken at different times from several locations and depths. The results can be used to establish patterns for that particular body of water.

Generally, as little time as possible should elapse between collecting the sample and analyzing it.

Depending on the test, special precautions in handling the sample may be necessary. This prevents natural interferences such as organic growth or loss or gain of dissolved gases. Each procedure describes sample preservatives and storage techniques for samples that are held for testing.

Acid Washing Bottles

If a procedure suggests acid-washing, use the following procedure:

Use chromic acid or chromium-free substitutes to remove organic deposits from glass containers. Rinse containers thoroughly with water to remove traces of chromium.

a) Clean the glassware or plasticware with laboratory detergent

(phosphate-free detergent is recommended).

b) Rinse well with tap water.

c) Rinse with a 1:1 Hydrochloric Acid Solution or 1:1 Nitric Acid

Solution. The nitric acid rinse is important for testing for lead.

d) Rinse well with deionized water. Up to 12-15 rinses may be

necessary if chromium is being determined.

e) Air dry.

SECTION I, continued

Wash glassware for phosphate determinations with phosphate-free detergents and acid-wash with 1:1 HCl. Thoroughly rinse the glassware with deionized water. For ammonia and Kjeldahl nitrogen, rinse with ammonia-free water.

Correcting for Volume Additions

If you use a large volume of preservative, correct for the volume of preservative added. This accounts for dilution due to the acid added to preserve the sample and the base used to adjust the pH to the range of the procedure. This correction is made as follows:

1. Determine the volume of initial sample, the volume of acid and base

added, and the total final volume of the sample.

2. Divide the total volume by the initial volume.

3. Multiply the test result by this factor.

Example:

A one-liter sample was preserved with 2 mL of nitric acid. It was neutralized with 5 mL of 5 N sodium hydroxide. The result of the analysis procedure was 10.00 mg/L. What is the volume correction factor and correct result?

Boiling Aids

Total Volume 1000 mL 2 mL 5 mL++ 1007 mL==

1007

------------- 1.007 volume correction factor==

1000

10.0 mg/L 1.007× 10.07 mg/L correct result==

Hach 1:1 Nitric Acid Pillows contain 2.5 mL of acid: correct for this volume. The addition of a Sodium Carbonate Power Pillow neutralizes the 1:1 Nitric Acid Pillow does not need to be corrected for.

Boiling is necessary in some procedures. Using a boiling aid such as boiling chips (Cat. no. 14835-31) reduces bumping. Bumping is caused by the sudden, almost explosive conversion of water to steam as it is heated. Avoid bumping; it may cause sample loss or injury.

Make sure the boiling aids will not contaminate the sample. Do not use boiling aids (except glass beads) more than once. Loosely covering the sample during boiling will prevent splashing, reduce the chances of contamination and minimize sample loss.

SECTION I, continued

Sample Filtration

Filtering separates particles from the aqueous sample. Filtration uses a medium, usually filter paper, to retain particles but pass solution. This is especially helpful when sample turbidity interferes with analysis. Two general methods of filtration are gravity and vacuum. Gravity filtration uses gravity to pull the sample though the filter paper. Vacuum filtration uses suction and gravity to move the sample through the filter. An aspirator or vacuum pump creates the suction. Vacuum filtration is faster than gravity filtration. Vacuum filter (see Figure 1) as follows:

1. Using tweezers, place a filter paper into the filter holder.

2. Place the filter holder assembly in the filtering flask. Wet the filter

with deionized water to ensure adhesion to the holder.

3. Position the funnel housing on the filter holder assembly.

4. While applying a vacuum to the filtering flask, transfer the sample to

the filtering apparatus.

5. Slowly release the vacuum from the filtering flask and transfer the

solution from the filter flask to another container.

Figure 1 Vacuum Filtration

REQUIRED APPARATUS FOR VACUUM FILTRATION

Description Unit Cat. No.

Filter Discs, glass 47 mm.................................................................. 100/pkg................2530-00

Filter Holder, membrane ......................................................................... each..............13529-00

Flask, filter, 500 mL ................................................................................ each..................546-49

Pump, vacuum, hand operated ................................................................each..............14283-00

Pump, vacuum, portable, 115 V ..............................................................each..............14697-00

Pump, vacuum, portable, 230 V ..............................................................each..............14697-02

SECTION I, continued

Many of the procedures in this manual use gravity filtration. The only labware required is filter paper, a conical funnel and a receiving flask. This labware is included under Optional Equipment and Supplies at the end of a procedure. Gravity filtration is better for retaining fine particles. For faster filtering, add solution until the filter paper cone is three-fourths filled. Never fill the cone completely. Gravity filter (see Figure 2) as follows:

1. Place a filter paper into the funnel.

2. Wet the filter with deionized water to ensure adhesion to the funnel.

3. Place the funnel into an erlenmeyer flask or graduated cylinder.

4. Pour the sample into the funnel.

Figure 2 Gravity Filtration

REQUIRED APPARATUS FOR GRAVITY FILTRATION

Description Unit Cat No.

Cylinder, graduated, 100 mL ...................................................................each ................. 508-42

Funnel, poly, 65 mm ................................................................................each ............... 1083-67

Filter Paper, 12.5 cm ................................................................................each ............... 1894-57

Flask, erlenmeyer, 125 mL ......................................................................each ................. 505-43

Testing for metals requires acid and heat to pretreat the sample. Since these conditions destroy filter paper, vacuum filtration with glass fiber filter discs is recommended. Also, glass filter discs, unlike paper, do not retain colored species.

SECTION I, continued

Temperature Considerations

For best results, most tests in this manual should be performed with sample temperatures between 20 °C (68 °F) and 25 °C (77 °F). If a test requires closer temperature control, notes in the procedure will indicate this.

Sample Dilution Techniques

Ten and 25 mL are the volumes used for most colorimetric tests. However, in some tests, the color developed in the sample may be too intense to be measured. Unexpected colors may develop in other tests. In both cases, dilute the sample to determine if interfering substances are present.

To dilute the sample easily, pipet the chosen sample portion into a clean graduated cylinder (or volumetric flask for more accurate work). Fill the cylinder (or flask) to the desired volume with deionized water. Mix well. Use the diluted sample when running the test.

To help with dilutions, Table 5 shows the amount of sample used, the amount of deionized water used to bring the volume up to 25 mL and the multiplication factor.

The concentration of the sample is equal to the diluted sample reading multiplied by the multiplication factor.

More accurate dilutions can be done with a pipet and a 100-mL volumetric flask (see Table 6 for more information). Pipet the sample and dilute to volume with deionized water. Swirl to mix.

Table 5 Sample Dilution Volumes

Sample

Volume (mL)

25.0 0.0 1

12.5 12.5 2

10.0

5.0

2.5

1.0

0.250

1 For sample sizes of 10 mL or less, use a pipet to measure the sample into the graduated

cylinder or volumetric flask.

mL deionized Water Used

to Bring the Volume to 25 mL

15.0 2.5

20.0 5

22.5 10

24.0 25

24.75 100

Multiplication

Factor

SECTION I, continued

Table 6 Multiplication Factors for Diluting to 100 mL

Sample Volume (mL) Multiplication Factor

1 100

250

520

10 10

25 4

50 2

Sample Dilution and Interfering Substances

Sample dilution may influence the level at which a substance may interfere. The effect of the interferences decreases as the dilution increases. In other words, higher levels of an interfering substance can be present in the original sample if it is diluted before analysis.

An Example:

Copper does not interfere at or below 100 mg/L for a 25.00 mL sample in a procedure. If the sample volume is diluted with an equal volume of water, what is the level at which copper will not interfere?

Total volume

------------- ----------------- ----------- Dilution factor= Sample volume

----------- 2=

12.5

Interference Level Dilution Factor× Interference level in sample=

100 2× 200=

The level at which copper will not interfere in the undiluted sample is at or below 200 mg/L.

SECTION I, continued

Using Pipets and Graduated Cylinders

When small sample quantities are used, the accuracy of measurements is important. Figure 3 illustrates the proper way of reading the sample level or the meniscus formed when the liquid wets the cylinder or pipet walls.

Figure 3 Reading the Meniscus

Rinse the pipet or cylinder two or three times with the sample to be tested before filling. Use a pipet filler or pipet bulb to draw the sample into the pipet. Never pipet chemical reagent solutions or samples by mouth. When filling a pipet, keep the tip of the pipet below the surface of the sample as the sample is drawn into the pipet.

Serological pipets have marks that indicate the volume of liquid delivered by the pipet. The marks may extend to the tip of the pipet or may be only on the straight portion of the tube. If the marks are only on the straight part of the tube, fill serological pipets to the zero mark and discharge the sample by draining the sample until the meniscus is level with the desired mark. If the serological pipet has marks extended to the tip of the pipet, fill the pipet to the desired volume and drain all the sample from the pipet. Then blow the sample out of the pipet tip for accurate measurements.

Volumetric (transfer) pipets have a bulb in the middle and a single ring above the bulb to indicate the volume of liquid when it is filled to the mark . To discharge a volumetric pipet, hold the tip of the pipet at a slight angle against the container wall and drain. Do not attempt to discharge the solution remaining in the tip of the pipet after draining. Volumetric pipets are designed to retain a small amount of sample in the pipet tip.

If sample drops stay on the walls of the pipet, the pipet is dirty and is not delivering the correct amount of sample. Wash the pipet thoroughly with a laboratory detergent or cleaning solution and rinse several times with deionized water.

SECTION I, continued

Using the TenSette Pipet

For best results use a new tip each time you pipet. After several uses, the pipet tip may retain some liquid, causing inaccurate delivery. Each pipet is supplied with 100 tips; order Hach replacement tips for best results.

Always use careful, even hand movements for best reproducibility. If the pipet does not operate smoothly, disassemble and coat the piston and retainer with high-quality stopcock grease. Also coat the metering turret lightly with grease. Refer to the TenSette Pipet manual.

For best pipetting accuracy, the solution and the room temperature should be between 20-25 °C.

Never lay the pipet down with the liquid in the tip. Solution could leak into the pipet and cause corrosion.

Operating the TenSette Pipet

1. Attach a clean tip by holding the pipet body in one hand and gently

pressing the large end of the pipet tip onto the tapered end of the pipet. Be sure a good seal is obtained.

2. Turn the turret cap to align the desired volume with the mark on the

pipet body.

3. Using a smooth motion, press down on the turret cap until it reaches

the stop. Immerse the tip about 5 mm (1/4 inch) below the solution surface to avoid drawing air into the pipet. Do not insert the tip any deeper or the delivery volume may be affected.

4. While maintaining a constant pressure, allow the turret to return

slowly to the extended position. A rapid return may affect the delivery volume.

5. With the turret up, take the tip out of the solution and move it to the

receiving vessel. Do not press on the turret cap while moving the pipet.

STEP 3 STEP 4 STEP 5

SECTION I, continued

6. Use the thumb and forefinger to twist the turret cap to the next higher

volume position to ensure quantitative transfer of the sample. The “F” position provides full blowout.

7. With the tip in contact with the side of the receiving vessel, slowly

and smoothly press down on the turret cap until it reaches the stop and the solution is completely discharged.

Mixing Water Samples

The following two methods may be helpful in tests that require mixing sample with chemicals (usually indicated by “swirl to mix” instructions).

1. When mixing sample in a square sample cell, swirl with a simple

2. Swirling is recommended when mixing samples in a graduated

This swirling procedure is the most gentle and offers the least interference from the atmosphere when testing for carbon dioxide and other gases. Both methods are simple but take a bit of practice in order to obtain the best results.

STEP 6

STEP 7

twisting motion; see Figure 4. Grasp the neck of the cell with the thumb and index finger of one hand. Rest the concave bottom of the cell on the tip of the index finger of other hand. Mix by rotating the cell quickly one way and then in the reverse direction.

cylinder or a titration flask. Grip the cylinder (or flask) firmly with the tips of three fingers; see Figure 5. Hold the cylinder at a 45-degree angle and twist the wrist. This should move the cylinder in an approximately 12-inch circle, creating enough rotation to complete the mixing in a few turns.

SECTION I, continued

Figure 4 Swirling a Sample Cell

Figure 5 Swirling a Graduated Cylinder

SECTION I, continued

Using Sample Cells

Orientation of Sample Cells

Two types of matched sample cells are shipped with the DR/2010; a matched pair of taller 25 mL sample cells and a shorter matched pair of 10 mL sample cells. Both types are matched with the spectrophotometer light beam passing through the side with the fill mark and the opposite side. Matched pairs have been tested and paired so that significant error will not be introduced because of variations in the glass. A solution in both cells should give the same absorbance (±0.002 Abs). For more information, see Sample Cell Matching, below.

To minimize variability of measurements using a particular cell, always place the cell into the cell holder with the same orientation. The cells are placed in the instrument with the fill marks facing left (viewer’s left).

In addition to proper orientation, the sides of the cells should be free of smudges, fingerprints, etc. to ensure accurate readings. Wipe the sides of the cells with a soft cloth to clean the surface before taking measurements.

Care of Hach 1-inch Sample Cells

Store sample cells in their boxes when not in use to protect them from scratching and breaking. It is good laboratory practice to empty and clean sample cells after analyses are complete--avoid leaving colored solutions in the cells for extended periods of time. Finish the cleaning procedure with a few rinses of deionized water and allow to dry. Individual procedures often recommend specific cleaning methods for special circumstances.

Cleaning Sample Cells

Most laboratory detergents can be used at recommended concentrations. Neutral detergents such as Neutracon are safer if regular cleaning is required, as in the case of protein residues.

If using a detergent, you can speed cleaning by increasing the temperature or using an ultrasonic bath.

Rinsing is more efficient when using distilled water.

SECTION I, continued

Sample Cell Matching

Sample cells shipped with the DR/2010 are matched and distortion-free. Nicks and scratches from normal use can cause an optical mismatch between two sample cells and introduce error in the test results. This type of error can sometimes be avoided by optically re-matching the sample cells as follows:

1. Turn the instrument on and select the constant-on mode. Wait 5

minutes for the lamp to warm up.

2. Enter the stored program for absorbance. Press

will show:

Abs.

0 ENTER. The display

3. Rotate the wavelength dial until the small display shows 510 nm or

the wavelength commonly used.

4. Pour at least 25 mL (10 mL for 10-mL cells) of deionized water into

each of two sample cells.

5. Place one sample cell into the cell holder. Orient the fill mark to the

left. Close the light shield.

6. Press:

ZERO. The display will show: 0.000 Abs.

7. Place the other sample cell into the cell holder using the same

orientation as in step 5. Close the light shield.

8. Wait about 3 seconds for the reading to stabilize. Record the result.

Two sample cells are matched when their absorbance readings are within

0.002 Abs of each other. If the cells do not match, there are two alternative options to purchasing a new set.

If more than two sample cells are on hand, repeat steps 7-8 for with these cells to determine if any match the original cell. If two cells match, mark them appropriately and keep them as a set.

As a last option, change the orientation of the cells to find a matched configuration. Repeat the steps above for two sample cells, placing both cells in the cell compartment with the fill marks facing forward. If the absorbance reading of the second cell is within +/- 0.002, the cells can be used as a matched set in that particular orientation. All future work with this particular set would require the same orientation. If necessary, repeat matching process with different orientations as needed.

SECTION I, continued

If the sample cells cannot be matched within ±0.002 Abs, they may still be used by compensating for the difference. For example, if the second cell reads 0.003 absorbance units higher than the first cell, correct future readings (when using these two cells) by subtracting 0.003 absorbance units (or the equivalent concentration) from the reading. Likewise, if the second cell reads -0.003 absorbance units, add that value to the reading.

Volume Measurement Accuracy

The 10-and 25-mL sample cells supplied with the spectrophotometer have fill marks to indicate either 10 mL or 25 mL. The fill marks are intended to measure the volume to be analyzed. Do not use these fill marks to perform sample dilutions.

If a sample must be diluted, use a pipet, graduated mixing cylinder and/or a volumetric flask for accurate measurement. When diluting, accuracy is important because a slight mistake in measuring a small sample will cause a substantial error in the result. For instance, a 0.1-mL mistake in the dilution of a 1.0-mL final volume produces a 10% error in the test result.

Volumes for standard additions can be measured in the 25-mL cells, but it is not recommended for the 10-mL cells due to a potentially excessive relative error. An error of 0.5 mL in 25 mL is only 2%, while a 0.5 mL error in 10 mL is 5%.

For 10 mL standard additions, follow this procedure:

1. Pipet 10.0 mL of sample into a clean, dry 10 mL cell

2. Add the standard (spike) to a 25 mL portion of sample in a 25-mL

3. Transfer 10 mL to another 10-mL cell (use fill mark) for analysis.

Using AccuVac Ampuls

AccuVac ampuls contain pre-measured powder or liquid in optical-quality glass ampuls.

1. Collect the sample in a beaker or other open container.

2. Place the ampul tip well below the sample surface and break the tip

(the unspiked sample).

mixing cylinder. Stopper and mix thoroughly.

off (see Figure 6) against the beaker wall. The break must be far enough below the surface to prevent air from being drawn in as the level of the sample lowers (the AccuVac Breaker may be used instead of breaking the ampul against the beaker side).

SECTION I, continued

3. Invert the ampul several times to dissolve the reagent. Do not place

your finger over the broken end; the liquid will stay in the ampul when inverted. Wipe the ampul with a towel to remove fingerprints, and other marks.

4. Insert the ampul into the AccuVac adapter in the DR/2010 and read

the results directly.

Figure 6 Using AccuVac Ampuls

1. 2.

Using Reagent Powder Pillows

Hach uses dry powdered reagents when possible. This minimizes leakage and deterioration problems. Some powders are packaged in individual, pre-measured, polyethylene “powder pillows” or foil pillows called PermaChem Open the powder pillows with nail clippers or scissors; see Figure 7.

pillows. Each pillow contains enough reagent for one test.

Figure 7 Opening Powder Pillows

SECTION I, continued

Using PermaChem Pillows

1. Tap the pillow on a hard surface to collect the powdered reagent in

the bottom.

2. Tear (or cut) across, from A to B, holding the pillow away from

your face.

3. Using two hands, push both sides toward each other to form a spout.

4. Pour the pillow contents into the sample cell and continue the

procedure according to the instructions.

Figure 8 Opening PermaChem Pillows

1. Tear 2. Push 3. Pour

Using the Pour-Thru Cell

The Pour-Thru Cell is an optional accessory that improves accuracy and makes measuring more convenient. It gives better results when measuring at very low levels because it avoids any error that may result between optical differences from single sample cells. Installation instructions for the Pour-Thru Cell are given in the Instrument Manual. Each procedure notes if the Pour-Thru Cell can be used; some procedures will not allow the use of a Pour-Thru cell.

The DR/2010 offers many methods that use 10-mL sample sizes. The Pour-Thru Cell cannot be used for procedures that use 10-mL sample sizes and reagents. This volume does not flush the cell well enough to avoid sample carryover errors. When possible, 25-mL reagents are listed for those who prefer to use the Pour-Thru Cell.

When the procedure instructs you to place a 25-mL sample cell into the cell holder, pour the solution into the funnel of the installed Pour-Thru Cell Assembly (unless noted in the procedure).

Avoid spilling solution onto the instrument. The funnel height and orientation may be adjusted for easier pouring.

SECTION I, continued

The funnel height also determines the speed of sample flow through the cell. The higher the funnel, the faster the flow. When properly adjusted, the funnel drains completely with the final level of liquid in the tube about 5 cm (2 inches) below the tip of the funnel. This adjustment minimizes air bubbles in the cell.

Measurement or instrument commands should only be made after the solution has stopped flowing through the cell.

Occasionally, remove the Pour-Thru Cell to check for accumulation of film on the windows. If the windows appear hazy, soak the cell in a detergent bath and rinse thoroughly with deionized water. The cell may be dissembled for cleaning. Do not over-tighten the screws during reassembly as the threads are easily stripped.

Always rinse thoroughly with deionized water after each series of tests, or more often if specified in the procedure.

Caution: Do not use or clean the Pour-Thru Cell with organic solvents such as acetone, chloroform, toluene or cyclohexanone.

Reagent and Standard Stability

Hach always strives to make stable formulations and package them to provide maximum protection. Most chemicals and prepared reagents do not deteriorate after manufacture. However, the way they are stored and the packaging can affect how long the reagents are stable. Light, bacterial action, and absorption of moisture and gases from the atmosphere can affect shelf life. Some chemicals may react with the storage container or they may react with other chemicals.

Chemicals supplied with the DR/2010 Spectrophotometer have an indefinite shelf life when stored under average room conditions, unless the packaging says something different. Product labels state any special storage conditions required. Otherwise, store reagents in a cool, dry, dark place for maximum life. It is always good practice to date chemicals when you receive them. Use older supplies first. If in doubt about the reagent shelf life, run a standard to check its effectiveness.

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Interferences

Substances in the sample may interfere with a measurement. Hach mentions common interferences in the test procedures. The reagent formulations eliminate many interferences. You can remove others with sample pretreatments described in the procedure.

If you get an unusual answer, a color that you don’t expect, or you notice an unusual odor or turbidity, the result may be wrong. Repeat the test on a sample diluted with deionized water; see Sample Dilution Techniques. Compare the result (corrected for the dilution) with the result of the original test. If these two are not close, the original result may be wrong and you should make an additional dilution to check the second test (first dilution). Repeat this process until you get the same corrected result twice in a row.

More information about interferences and methods to overcome them is contained in Standard Additions and the General Introduction section of APHA Standard Methods. Hach urges the analyst to obtain this book and refer to it when problems are encountered.

pH Interference

Many of the procedures in this manual only work within a certain pH range. Hach reagents contain buffers to adjust the pH of the typical sample to the correct pH range. However, the reagent buffer may not be strong enough for some samples. This occurs most often with highly buffered samples or samples with extreme sample pH.

The Sampling and Storage section of each procedure gives the proper pH range for the sample.

Adjust the sample to the proper pH range before testing. If this information is not given, follow these steps:

1. Measure the pH of your analyzed sample with a pH meter. For

measuring K

2. Prepare a reagent blank using deionized water as the sample. Add all

reagents called for in the procedure. Timer sequences, etc., may be ignored. Mix well.

3. Measure the pH of the reagent blank with a pH meter.

4. Compare the pH values of your analyzed sample with the

reagent blank.

or Cl- , use pH paper.

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5. If there is little difference in the values of your analyzed sample

and the reagent blank, then pH interference is not the problem. Follow the Accuracy Check given in the procedure to more clearly identify the problem.

6. If there is a large difference between the value of your analyzed

sample and the reagent blank, adjust the sample pH to the value of the reagent blank. Adjust the sample pH to this same pH for all future samples before analysis. Use the appropriate acid, usually nitric acid, to lower the pH. Use the appropriate base, usually sodium hydroxide, to raise the pH. Adjust the final result for any dilution caused by adding acid or base; see Correcting for Volume Additions.

7. Analyze the sample as before.

8. Some purchased standards may be very acidic and will not work

directly with Hach procedures. Adjust the pH of these standards as described above. Adjust the final concentration of the standard for the dilution. The Hach standard solutions suggested in the procedures are formulated so that no pH adjustment is necessary.

Accuracy and Precision

Accuracy is the nearness of a test result to the true value. Precision is how closely repeated measurements agree with each other. Although good precision suggests good accuracy, precise results can be inaccurate. The following paragraphs describe how to improve accuracy and precision of analyses by using Standard Additions.

Figure 9 Precision and Accuracy Illustrated

Not accurate,

not precise

One of the greatest aids is knowing what is in the sample. You don’t need to know exactly what is in each sample, but be aware of substances that are likely to interfere in the analysis method you use. When using a method, it may be helpful to determine if those interferences are present.

Accurate,

not precise

Precise,

not accurate

Accurate and

precise

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Standard Additions

Standard Additions is a common technique for checking test results. Other names are “spiking” and “known additions.” The technique can test for interferences, bad reagents, faulty instruments, and incorrect procedures.

Perform Standard Additions by adding a small amount of a standard solution to your sample and repeating the test. Use the same reagents, equipment, and technique. You should get about 100% recovery. If not, you have an identifiable problem.

If Standard Additions works for your test, a Standard Additions Method section will be in the procedure under Accuracy Check. Follow the detailed instructions given.

If you get about 100% recovery for each addition, everything is working right and your results are correct.

If you don’t get about 100% recovery for each addition, a problem exists. You can tell if you have an interference. Repeat the Standard Additions using deionized water as your sample. If you get about 100% recovery for each addition, you have an interference. If you didn’t get good recoveries with the deionized water, the following checklist may help to find the problem quickly:

1. Check to see that you are following the procedure exactly:

a) Are you using the proper reagents in the proper order? Are you

using 10-mL reagents with a 10-mL sample or 25-mL reagents with a 25-mL sample?

b) Are you waiting the necessary time for color to develop?

c) Are you using the correct glassware?

d) Is the glassware clean?

e) Does the test need a specific sample temperature?

f) Is the sample’s pH in the correct range?

Hach’s written procedure should help you to answer these questions.

2. Check your reagents. Repeat the Standard Additions using new, fresh

reagents. If your results are good, the original reagents were bad.

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3. Check the performance of your instrument. Follow the instructions in

the Maintenance section of the DR/2010 Instrument Manual.

4. If nothing else is wrong, the standard is almost certainly bad. Repeat

the Standard Additions with a new standard.

If the check list does not determine the problem, use the decision tree (Figure 10) and explanation of each branch, below, to identify the problem.

Branch A

Suppose a single standard addition to the sample did not give the correct concentration increase. A possible cause could be interferences. Other causes include defective reagents, incorrect technique, a defective instrument/apparatus or defective standard used for the standard addition.

If interferences are known or assumed to be absent, proceed to Branch B. If interferences are known to be present, proceed to Branch C.

Branch B

Perform multiple standard additions on a sample of deionized water as in the following example using iron as the analyte of interest:

1. Pour 25 mL of deionized water into a 25-mL sample cell.

2. Add 0.1 mL of a 50-mg/L iron standard solution to a second 25 mL

sample of deionized water.

3. Add 0.2 mL of the same standard to a third 25 mL sample of

deionized water.

4. Add 0.3 mL of the same standard to a fourth 25 mL sample of

deionized water. Analyze all these samples for iron.

5. Tabulate the data as shown below:

mL of standard Added mg/L of Standard Added mg/L of Iron Found

000

0.1 0.2 0.2

0.2 0.4 0.4

0.3 0.6 0.6

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Figure 10 Standard Additions Decision Tree

Did a Single Standard Addition Give the Correct Recovery?

Is the Procedure in

Use Correct?

Use Correct

Procedure and

Repeat B

Are

Interferences

Present?

Do Multiple

Standard Additions

On DI Water Give

Correct Recovery?

Yes

Do Multiple Standard Additions On Sample

Give Uniform Increments?

Analysis

Is Incorrect

Analysis May

be Correct

Yes

Are

Interferences

Present?

Analysis

Is Correct

Yes

Are the Reagents Working Properly?

Repeat B with

New Reagents

Is Instrument Apparatus Working Properly?

No Yes

Repair/Replace

Instrument Apparatus

and Repeat B

Yes

Standards Defective

Repeat B with New

Standards

SECTION I, continued

The data show several points:

• The chemicals, instrument, procedure/technique and standards are

working correctly because the iron added to the water sample was completely recovered in the same uniform steps that match the standard addition increments.

• Because iron added to the deionized water was recovered, but iron

added to an actual sample was not recovered (Branch A), the sample contains an interference which prevents the test reagents from working properly.

• An iron analysis previously done on the actual sample using this

method gave an inaccurate result.

If the results of multiple standard additions give the correct increment for each addition, proceed to Branch C.

If the results of multiple standard additions do not give the correct increment for each addition, go to Branch D.

Branch C

If interfering substances are present, the analysis may be incorrect. However, with multiple standard additions, it may be possible to arrive at an approximate result if the increases are uniform.

Suppose the sample result for iron was 1.0 mg/L. Because interferences may be present, a standard addition of 0.1 mL of a 50 mg/L iron standard to a 25 mL sample is made. The expected increase in the iron concentration is 0.2 mg/L, but the actual increase is 0.1 mg/L. Then 0.2 and 0.3 mL of the same standard are added to two more 25 mL samples and analyzed for iron.

If there is a uniform increase in concentration between each addition (i.e., 0.1 mg/L difference between each addition), use Branch G. If the increase in concentration is not uniform (i.e., 0.1, 0.08, 0.05), go to Branch F.

Branch D

Carefully check the instructions for the test. Make sure to use the correct reagents in the correct order. Be sure the colorimeter is adjusted to the correct wavelength and the glassware in use is what is required. Be sure time for color development and the sample temperature are as specified. If the procedure technique was incorrect, repeat Branch B. If the procedure was correctly followed, proceed to Branch E.

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Branch E

Check the reagent performance. This may be done by obtaining a fresh lot of reagent or by using a known standard solution to run the test. Make sure the color development time given in the procedure is equal to the time required for the reagent in question. If the reagent(s) is defective, repeat Branch B with new reagents. If the reagents are good, proceed with Branch H.

Branch F

Examples of non-uniform increments between standard additions are shown below.

Example A

mL of Standard Added mg/L Standard Added mg/L Found

Example B

001.0

0.1 0.2 1.10

0.2 0.4 1.18

0.3 0.6 1.23

mL of Standard Added mg/L Standard Added mg/L Found

000

0.1 0.2 0

0.2 0.4 0.2

0.3 0.6 0.4

These examples show the effect of interferences on the standard addition. Data plotted on the graph in Figure 10 for samples A and B show that the four data points do not lie on a straight line.

The plot for sample A illustrates an interference that becomes progressively worse as the concentration of the standard increases. This type of interference is uncommon and may be caused by an error or malfunction of the procedure, reagents or instrument. It is recommended Branch B be performed to verify the supposed interference.

The plot for sample B shows a common chemical interference which becomes less or even zero as the concentration of standard increases. The graph shows the first addition was consumed by the interference and the remaining additions gave the correct increment of 0.2 mg/L.

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The apparent interference in Example B could be the result of an error made in the standard addition. Repeat the analysis to see if an error was made during standard addition. If not, the method is not appropriate for the sample matrix. When these two types of interferences occur, try to analyze the sample with another method which uses a different type of chemistry.

Figure 11 Multiple Standard Additions Graph

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Branch G

Examples of uniform increments between standard additions are given below.

Example C

mL of Standard Added mg/L Standard Added mg/L Found

The plot for sample C illustrates a common interference with a uniform effect on the standard and the substances in the sample. The four data points form a straight line which may be extended back through the horizontal axis. The point where the line meets the axis can be used to determine the concentration of the substance you are measuring.

In this example, the first analysis gave 0.4 mg/L. After extrapolating the line to the horizontal axis, the graph shows the result should be much closer to the correct result: 0.8 mg/L.

000.4

0.1 0.2 0.5

0.2 0.4 0.6

0.3 0.6 0.7

Apparent interferences may also be caused by a defect in the instrument or standards. Before assuming the interference is chemical, check Branch B.

Example D

mL of Standard Added mg/L Standard Added mg/L Found

000

0.1 0.2 0.2

0.2 0.4 0.4

0.3 0.6 0.6

The plot for sample D illustrates a problem for the analyst. The increments are uniform and the recovery of the standard was complete. The result of the first analysis was 0 mg/L and the line extrapolates back through 0 mg/L. If interferences are known to be present, the interferences may be present in an amount equal to the substance in question, preventing the analyst from finding the substance. This would be an uncommon situation.

SECTION I, continued

Branch H

Check operation of the instrument and/or apparatus used to perform the test. Perform the wavelength and linearity checks in the instrument manual. Check glassware used in the procedure and make sure it is extremely clean. Dirty pipets and graduated cylinders can cause contamination and will not deliver the correct volume.

If a defect is found in the instrument and/or apparatus, repeat Branch B after repair or replacement. If the instrument and apparatus are working, proceed with Branch I.

Branch I

After determining the procedure, reagents, instrument and/or apparatus are correct and working properly, you may conclude the only possible cause for standard additions not functioning correctly in deionized water is the standard used for performing standard additions. Obtain a new standard and repeat Branch B.

Branch J

If the standard additions gives the correct result, the analyst must then determine if an interfering substance(s) is present. If interfering substances are present, proceed to Branch C. If they are not present, the analysis is correct.

If you still cannot identify the problem, extra help is available. Please call our Technical Support Group at 800-227-4224 (U.S.A.) or 970-669-3050. A representative will be happy to help you.

Method Performance

Estimated Detection Limit

Ranges for chemical measurements have limits. The lower limit is important because it determines whether a measurement is different from zero. Many experts disagree about the definition of this detection limit, and determining it can be difficult. The Code of Federal Regulations (40 CFR, Part 136, Appendix B) provides a procedure to determine the “Method Detection Limit” or MDL. The MDL is the lowest concentration that is different from zero with a 99% level of confidence. A measurement below this MDL may be useful, but there is a greater chance that it is actually zero.

The MDL is not fixed; it varies for each reagent lot, instrument, analyst, sample type, etc. Therefore, a published MDL may be a useful guide, but is only accurate for a specific set of circumstances. Each analyst should

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determine a more accurate MDL for each specific sample matrix using the same equipment, reagents and standards that will routinely be used for measurements.

Hach provides a value called the Estimated Detection Limit (EDL) for USEPA accepted and approved programs. It is the calculated lowest average concentration in a deionized water matrix that is different from zero with a 99% level of confidence. Specifically, it is the upper 99% confidence limit for zero concentration based on the calibration data used to prepare the pre-programmed calibration curve. Do not use the EDL as a MDL. The conditions for MDL determination must be exactly the same as the conditions used for analysis. The EDL may be useful to the analyst as a starting point in determining a MDL or as a way to compare methods. Measurements below the EDL may also be valuable because they can show a trend, indicate the presence of analyte and/or provide statistical data. However, these values have a large uncertainty.

Method Detection Limit (MDL)

This method is in accordance with the USEPA definition in 40 CFR, Part 136, Appendix B in the 7-1-94 edition.

The USEPA defines the method detection limit (MDL) as the minimum concentration that can be determined with 99% confidence that the true concentration is greater than zero. Since the MDL will vary from analyst to analyst, it is important that analysts determine the MDL based on their unique operating conditions.

The procedure for determining MDL is based on replicate analyses at a concentration 1 to 5 times the estimated detection limit. The MDL value is calculated from the standard deviation of the replicate study results multiplied by the appropriate Student’s t value for a 99% confidence interval. For this definition, the MDL does not account for variation in sample composition and can only be achieved under ideal conditions.

1. Estimate the detection limit. Use the Hach estimated detection

limit (EDL) value stated in the Method Performance section of the analysis procedure.

2. Prepare a laboratory standard of the analyte in deionized water which

is free of the analyte that is 1 to 5 times the estimated detection limit.

3. Analyze at least 7 portions of the laboratory standard and record

each result.

4. Calculate the average and standard deviation (s) of the results.

SECTION I, continued

5. Compute the MDL using the appropriate Student’s t value (see table

below) and the standard deviation value:

MDL = Student’s t x s

Number of Test Portions Student’s t Value

For example:

The EDL for measuring iron using the FerroZine method is 0.003 mg/L. An analyst accurately prepared 1 liter of a 0.010 mg/L (about 3x the EDL) laboratory standard by diluting a 10-mg/L iron standard in iron-free deionized water.

Eight portions of the standard were tested according to the FerroZine method with the following results:

73.143

82.998

92.896

10 2.821

Sample # Result (mg/L)

10.009

20.010

30.009

40.010

50.008

60.011

70.010

80.009

Using a calculator program, the average concentration = 0.010 mg/L and the standard deviation (s) = 0.0009 mg/L

Based on the USEPA’s definition, calculate the MDL as follows:

MDL for FerroZine method = 2.998 (Student’s t ) x 0.0009 (s)

MDL = 0.003 mg/L (agrees with initial estimate)

Note: Occasionally, the calculated MDL may be very different than Hach’s estimate of the detection limit. To test how reasonable the calculated MDL is, repeat the procedure using a standard near the calculated MDL. The average result calculated for the second MDL derivation should agree with the initial

SECTION I, continued

calculated MDL. Refer to 40 CFR, Part 136, Appendix B (7-1-94), pages 635-637 for detailed procedures to verify the MDL determination.

Note: Run a laboratory blank, containing deionized water without analyte, through the test procedure to confirm that the blank measurement is less than the calculated MDL. If the blank measurement is near the calculated MDL, repeat the MDL procedure using a separate blank for analysis for each standard solution portion analyzed. Subtract the average blank measurement from each standard and use the corrected standard values to calculate the average and standard deviation used in the MDL.

Precision

Every measurement has a degree of uncertainty. Just as a ruler with

0.1-mm markings leaves some doubt as to the exact length of a measurement, chemical measurements also have some degree of uncertainty. The quality of the entire calibration curve determines the precision.

Uncertainty in chemical measurements may be due to systematic errors and/or random errors. A systematic error is a mistake that is always the same for every measurement made. For example, a blank can add to each measurement for a specific compound, giving consistently high results (a positive bias). Random errors are different for every test and add either positive or negative bias. Random errors may be caused by variation in analytical technique and cause response variation. Hach chemists work hard to eliminate systematic errors in Hach procedures using Hach reagents, but response variation occurs in all chemical measurements.

Estimating Precision

The method performance section in each procedure provides an estimate of the procedure’s precision. Two types of estimates are used throughout this manual. Most of the procedures use a “replicate analysis” estimate, based on real data. Some newer procedures use a 95% or 99% confidence interval, which is based on the calibration generated data for that particular chemistry.

In replicate analysis, a Hach chemist prepares a specific concentration of the analyte in a deionized water matrix. The standard is then analyzed seven individual times with the two reagent lots used in the calibration (14 total samples). A standard deviation of the two sets of seven values is calculated. The larger value is reported in the method. The reported value provides an estimate of the “scatter” of results at a particular point in the calibration curve.

In the confidence interval technique, an estimate is obtained from the calibration data itself, with no additional replicate analyses. In this case,

SECTION I, continued

the precision is the 95 or 99% confidence interval for the stated concentrations. The precision range is an estimate of the average response variation and is based on multiple reagent lots and instruments used in the calibration. Therefore, it will not exactly predict the true precision range for each reagent lot, but does provide a useful estimate.

In either case, it is important to stress that the estimates are based on the deionized water matrix. Precision on real samples with varying matrices can be quite different than these estimates.

Selecting the Best Wavelength

When developing a new procedure or using procedures that are sensitive to wavelength, it is normal to select the wavelength where the instrument gives the greatest absorbance (see Figure 12). Because Hach chemists have selected the best wavelength for the procedures in this manual, selecting the wavelength is not necessary for most procedures.

Figure 12 Selecting the Best Wavelength

1.0

500 505 510 515 520

Absorbance

400 450 500 550 600 650 700

0.0

Wavelength (nm)

SECTION I, continued

To select the best wavelength on the DR/2010:

1. Turn the instrument ON. Select the constant-on mode. Wait 5 minutes

for the instrument to warm up.

2. Enter the stored program for absorbance. Press:

0 ENTER.

The display will show: Abs

3. Rotate the wavelength dial until the small display shows the

approximate wavelength of interest.

Note: Sample color provides a good indication of what wavelength region to use. A yellow solution absorbs light in the 400-500 nm region. A red solution absorbs light between 500-600 nm. A blue solution absorbs light in the 600-700 nm range.

4. Prepare the sample and blank for analysis. FIll the appropriate sample

cells with the blank and the sample solutions (cells can be 10- or 25-mL cells, COD vial, 1-cm vials, etc.).

5. Place the blank in the cell holder. Orient the fill mark to your right.

Close the light shield.

6. Press:

ZERO. The display should read: 0.000 Abs

7. Place the prepared sample into the cell holder. Close the light shield.

Read the absorbance.

8. Increase the wavelength so it is at least 100 nm greater than the range

of interest. Re-zero as in Steps 5-6. Measure and record the absorbance of the sample.

9. Repeat, decreasing the wavelength by 50 nm. Re-zero, then measure

and record the absorbance at each increment. Continue this process through the wavelength range of interest. Note the wavelength of greatest absorbance (see Tabl e 7 as an example).

Table 7 Example of Initial Wavelength Search

Wavelength Absorbance

550 nm 0.477

500 nm 0.762

450 nm 0.355

400 0.134

1 This indicates 500 nm as the region to search for the best wavelength.

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10. Adjust the wavelength to 50 nm more than the highest absorbance

point on the initial search (step 9). Re-zero as in Steps 5 and 6.

11. Measure and record the absorbance. Repeat, decreasing the

absorbance in 5-nm steps. Re-zero, then measure and record the absorbance at each increment. Continue until the entire range of interest is measured (see Tab le 8 as an example).

Table 8 Example of Intermediate Wavelength Search

Wavelength Absorbance

520 0.748

515 0.759

510 0.780

505 0.771

500 0.771

495 0.651

490 0.590

1 This indicates the best wavelength to use is around 510 nm.

12. Increase the wavelength to 10 nm above the highest absorbance in

Step 11. Re-zero as in Steps 5 and 6. Measure and record the absorbance. Repeat the measuring process (re-zeroing is not necessary at each increment), decreasing the wavelength by 1 nm each time.

Table 9 Example of Detailed Wavelength Search

Wavelength Absorbance

512 0.769

511 0.773

510 0.780

509 0.787

508 0.781

597 0.764

1 The optimum wavelength is 509 nm.

13. Check to be sure there is enough difference in absorbance between

samples with low and high analyte concentrations by measuring two sample solutions that contain the expected low and high concentrations of analyte at the optimum wavelength. The change in absorbance caused by increases/decreases in concentration depends on the sensitivity of the procedure and chemistry. Chemistries with

SECTION I, continued

small absorbance changes are less sensitive, but tend to have larger ranges. Chemistries with large absorbance changes are more sensitive, but tend to have smaller ranges.

Adapting HACH Procedures to Other Spectrophotometers

Hach procedures may be used with other spectrophotometers if calibration curves that convert absorbance or %T to concentration are made. Regardless of the spectrophotometer used, prepare the sample and calibration standards following the Hach procedure and use the optimum wavelength used in the Hach procedure.

The example below describes a calibration for iron in the 0-2.4 mg/L range. A series of iron standards are prepared and measured to establish the calibration curve. The absorbance vs. concentration is plotted on linear graph paper (as in Figure 11, Multiple Standard Additions Graph) or %T vs. concentration is plotted on semi-logartihmic paper. Points on the graph are connected with a smooth line (curved or straight). If necessary, use the curve to make a calibration table.

Preparing a Calibration Curve

1. Prepare five or more standards of known concentration that cover the

expected range of the test. Run tests as described in the procedure on each prepared standard. Then pour the customary volume of each known solution into a separate clean sample cell of the type specified for your instrument.

2. Select the proper wavelength. Standardize (zero) the instrument using

an untreated water sample or a reagent blank, whichever the procedure instructs you to use.

3. Measure and record the %T or absorbance of the known solutions.

To use %T vs. concentration see section %T Versus Concentration

Calibration. To use absorbance vs. concentration, see section Absorbance Versus Concentration Calibration.

%T Versus Concentration Calibration

If measuring %T, use semilogarithmic graph paper and plot %T (vertical scale) versus concentration (horizontal scale). For Figure 13, iron standard solutions of 0.1, 0.2, 0.4, 0.8, 1.2, 1.6 and 2.0 mg/L were measured on a Spectronic 20 at 500 nm using half-inch test tubes. Results were plotted and the calibration table values were extrapolated from the curve (Table 10).

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Figure 13 Logarithmic Calibration Curve

100

PERCENT TRANSMITTANCE

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

2.20

2.40

mg/L IRON

To convert %T readings to concentration, prepare a table such as Tabl e 10 and select the appropriate line from the “%T Tens” column and the appropriate column from the %T Units columns. The %T Ten value is the first number of the %T reading and the %T Units value is the second number of the %T reading. For example, if the instrument reading was 46%, the 40 line in the %T Tens column and the 6 column in the %T Units would be selected. The cell where these two intersect (0.78 mg/L) is the iron concentration of the sample.

SECTION I, continued

Table 10 Calibration Table

Tens

10 2.30 2.21 2.12 2.04 1.97 1.90 1.83 1.77 1.72 1.66

20 1.61 1.56 1.51 1.47 1.43 1.39 1.35 1.31 1.27 1.24

30 1.20 1.17 1.14 1.11 1.08 1.04 1.02 0.99 0.97 0.94

40 0.92 0.89 0.87 0.84 0.82 0.80 0.78 0.76 0.73 0.71

50 0.69 0.67 0.65 0.64 0.62 0.60 0.58 0.56 0.55 0.53

60 0.51 0.49 0.48 0.46 0.45 0.43 0.42 0.40 0.39 0.37

70 0.36 0.34 0.33 0.32 0.30 0.29 0.28 0.26 0.25 0.24

80 0.22 0.21 0.20 0.19 0.17 0.16 0.15 0.14 0.13 0.12

90 0.11 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01

01234567 8 9

% Units

Absorbance Versus Concentration Calibration

If absorbance values are measured, plot the results on linear graph paper. Plot the absorbance value on the vertical axis and the concentration on the horizontal axis.

Plot increasing absorbance values from bottom to top. Plot increasing concentration values from left to right. Values of 0.000 absorbance units and 0 concentration will begin at the bottom left corner of the graph. A calibration table can be extrapolated from the curve or the concentration values can be read directly from the graph. Or determine an equation for the line using the slope and y-intercept.

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USEPA Approved and Accepted Definitions

The United States Environmental Protection Agency (USEPA) establishes limits for maximum contamination levels of certain constituents in water. It also requires that specific methodology be used to analyze for these constituents. These methods originate from several sources. The USEPA has developed some of these methods. In other cases, the USEPA has evaluated and approved methods developed by manufacturers, professional groups and public agencies such as:

• American Public Health Association

• American Water Works Association

• Water Environmental Federation

• American Society for Testing and Materials

• United States Geological Survey

• Associates of Official Analytical Chemists

All USEPA-approved methods are cited in the Federal Register and compiled in the Code of Federal Regulations (CFR). USEPA approved methods may be used for reporting results to the USEPA and other regulatory agencies.

USEPA Accepted

Hach has developed several procedures that are equivalent to USEPA approved methods. Even though minor modifications exist, the USEPA has reviewed and accepted certain procedures for reporting purposes. These methods are not published in the Federal Register, but are referenced to the equivalent USEPA method in the procedure.

SECTION II SAMPLE PRETREATMENT

Digestion

Several procedures require sample digestion. Digestion uses chemicals and heat to break down a substance into components that can be analyzed. This section has three different digestion procedures.

The Hach Digesdahl system is a process that yields a digest suitable for the determination of metals, total phosphorus and total kjeldahl nitrogen (TKN). It is rapid, convenient and the method of choice.

For USEPA reporting purposes, USEPA-approved digestions are required. USEPA presents two digestions (mild and vigorous) for metals analysis. These are much more inconvenient and time consuming compared to the Hach Digesdahl system. Other digestion procedures are required for mercury, arsenic, phosphorus and TKN.

EPA Mild Digestion with Hot Plate for Metals Analysis Only

1. Acidify the entire sample at the time of collection with concentrated

nitric acid by adding 5 mL of acid per liter (or quart) of sample.

2. Transfer 100 mL of well-mixed sample to a beaker or flask. Add 5 mL

of distilled 1:1 hydrochloric acid (HCl).

3. Heat using a steam bath or hot plate until the volume has been reduced to

15-20 mL. Make certain the sample does not boil.

4. After this treatment, the sample may be filtered to remove any

insoluble material.

5. Adjust the digested sample to pH 4 by drop-wise addition of 5.0 N

Sodium Hydroxide Standard Solution. Mix thoroughly and check the pH after each addition.

6. Quantitatively transfer the sample with deionized water to a 100-mL

volumetric flask and dilute to volume with deionized water. Continue with the procedure. This mild digestion may not suffice for all sample types. A reagent blank also should be carried through the digestion and measurement procedures.

SECTION II, continued

EPA Vigorous Digestion with Hot Plate for Metals Analysis Only

A vigorous digestion can be followed to ensure all organo-metallic bonds are broken.

1. Acidify the entire sample with redistilled 1:1 Nitric Acid Solution to a

pH of less than two. Do not filter the sample before digestion.

2. Transfer an appropriate sample volume (see Table 11) into a beaker

and add 3 mL of concentrated redistilled nitric acid.

3. Place the beaker on a hot plate and evaporate to near dryness, making

certain the sample does not boil.

4. Cool the beaker and add another 3 mL of the concentrated redistilled

nitric acid.

5. Cover the beaker with a watch glass and return it to the hot plate.

Increase the temperature of the hot plate so that a gentle reflux occurs. Add additional acid, if necessary, until the digestion is complete (generally indicated when the digestate is light in color or does not change color or appearance with continued refluxing).

6. Again, evaporate to near dryness (do not bake) and cool the beaker. If

any residue or precipitate results from the evaporation, add redistilled 1:1 hydrochloric acid (5 mL per 100 mL of final volume). See Table 11.

7. Warm the beaker. Add 5 mL of 5.0 N sodium hydroxide and

quantitatively transfer the sample with deionized water to a volumetric flask. See Table 11 below for the suggested final volume.

8. Adjust the sample to pH 4 by drop-wise addition of 5.0 N Sodium

Hydroxide Standard Solution; mix thoroughly and check the pH after each addition. Dilute to volume with deionized water. Multiply the result by the correction factor in Table 11. A reagent blank also should be carried through the digestion and measurement procedures.

Table 11 Vigorous Digestion Volumes

Expected Metal

Concentration

1 mg/L 50 mL 10 mL 200 mL 4

10 mg/L 5 mL 10 mL 200 mL 40

100 mg/L 1 mL 25 mL 500 mL 500

Suggested Sample

Vol. for Digestion

Suggested Volume

of 1:1 HCl

Suggested Final

Volume After

Digestion

Correction Factor

SECTION II, continued

General Digesdahl Digestion (Not USEPA accepted)

Many samples may be digested using the Digesdahl Digestion Apparatus (Cat. No. 23130). It is designed to digest many types of samples such as oils, wastewater, sludges, feeds, grains, plating baths, food, and soils. In this procedure the sample is oxidized by a mixture of sulfuric acid and hydrogen peroxide. Digestion of a dry sample requires less than ten minutes, while liquid samples require about 1 minute/mL. The digestion is done in a special flat-bottomed 100-mL volumetric flask. Aliquots (sample portions) are taken for analysis using colorimetric methods.

Procedures for digestion and using the Digesdahl Digestion Apparatus are based on the type and form of the sample, and are found in the Digesdahl Digestion Apparatus Instruction Manual, which is included with each Digesdahl Digestion Apparatus.

Distillation

Distallation Applications for the General Purpose Distillation Apparatus include:

• fluoride • phenols

• albuminoid nitrogen • selenium

• ammonia nitrogen • volatile acids

Arsenic and cyanide require specialty glassware sets in addition to the General Purpose Set (the Arsenic Distillation Apparatus and the Cyanide Distillation Apparatus). All connecting glassware is manufactured with threaded connectors for ease and safety. The General Purpose Heater provides efficient heating and the Support Apparatus anchors the glassware.

SECTION II, continued

Figure 14 General Purpose Distillation Apparatus with Heater and Support Apparatus

SECTION III WASTE MANAGEMENT AND SAFETY

Waste Management

This section provides guidelines for laboratory waste management. It should assist you in complying with USEPA regulations governing waste management. It summarizes basic requirements, but does not contain all USEPA regulations. It does not relieve people from complying with all regulations contained in the Code of Federal Regulations. Regulations change regularly and additional state and local laws may apply to you. Each waste generator is responsible for knowing and obeying these laws.

Waste Minimization

Waste minimization is the foundation of good waste management. Minimizing waste greatly reduces the disposal problems and expense. If possible, try to generate less waste rather than recycle or re-use it. For laboratories, ways to reduce waste include:

• Use the smallest sample size possible.

• Choose methods that use non-hazardous or “less” hazardous reagents

when possible.

• Buy chemicals in small quantities which will be used before they

expire. This eliminates disposal of out-dated materials.

• Clean glassware and laboratory apparatus with non-hazardous soaps

Regulatory Overview

Federal waste disposal regulations were issued in accordance with the Resource Conservation and Recovery Act (RCRA). They are given in Title 40 Code of Federal Regulations (CFR) part 260. The Act controls all forms of solid waste disposal and encourages recycling and alternative energy sources. The major emphasis is controlling hazardous waste disposal. The regulations create a system to identify wastes and track waste generation, transport, and ultimate disposal. Each facility involved in managing hazardous waste must be registered with the USEPA. This includes the generator, transporters, and treatment, storage, and disposal facilities (TSDF).

Under federal regulations, there are three categories of generators with increasingly more strict regulation for larger quantity generators. The categories are based on the amount of hazardous waste generated in any given month.

when possible, rather than solvents or acids which may be hazardous.

SECTION III, continued

The categories are as follows:

• Conditionally Exempt Small Quantity Generator - less than 100 kg

(220 lb.) per month

• Small Quantity Generator - between 100 kg (220 lb.) and 1,000 kg

(2,200 lb.) per month

• Large Quantity Generator - greater than 1,000 kg (2,200 lb.)

per month

Note: If a laboratory generates acutely hazardous waste (as defined on 40 CFR

261) or accumulates more than a certain amount of waste, the facility may be moved into a larger generator status. Check with your environmental compliance manager or state and local officials to determine which category your facility is in.

Hazardous Waste Definition

For regulatory purposes, a “hazardous waste” is a material which is subject to special laws by the USEPA under 40 CFR 261. In addition, many states or local authorities regulate additional materials as hazardous waste. Be aware that many very toxic compounds are not regulated by this definition of hazardous waste. However, improper management or disposal of these compounds may lead to legal problems under other laws such as CERCLA (Superfund) or common law tortes.

The 40 CFR 261 defines a hazardous waste as a solid waste which is not excluded from regulation and meets any of the following criteria:

• It is a discarded commercial chemical product, off-specification

species, container residue, or spill residue of materials specifically listed in 40 CFR 261.33;

• It is a waste from a specific source listed in 40 CFR 261.32;

• It is a waste from a non-specific source listed in 40 CFR 261.31; or

• It displays any of the following characteristics of hazardous waste

defined in 40 CFR 261.20-24:

• ignitability

• corrosivity

• reactivity

• toxicity

There are many exceptions to these regulations, and each generator should review the regulations and determine if they are excluded from the regulations.

SECTION III, continued

Characteristic Hazardous Waste Codes

Hazardous wastes are managed by specific codes assigned in 40 CFR

261.20-261.33. These codes are provided to help you identify hazardous waste. The generator is responsible for making the actual waste code determination.

Selected characteristic waste codes for chemicals which may be generated using Hach methods for water analysis are given in the following table. A complete list of waste codes is found in 40 CFR 261.24.

USEPA Code Characteristic CAS No.

D001 Ignitability na na

D002 Corrosivity na na

D003 Reactivity na na

D004 Arsenic 6440-38-2 5.0

D005 Barium 6440-39-3 100.0

D018 Benzene 71-43-2 0.5

D006 Cadmium 7440-43-9 1.0

D022 Chloroform 67-66-3 6.0

D007 Chromium 7440-47-3 5.0

D008 Lead 7439-92-1 5.0

D009 Mercury 7439-97-6 0.2

D010 Selenium 7782-49-2 1.0

D011 Silver 7440-22-4 5.0

How to Determine if Waste is Hazardous

Federal laws do not require you to test a material to decide if it is a hazardous waste. You may apply product knowledge to decide if a material is hazardous. Often, information on a material safety data sheet (MSDS) is enough to decide. If the product is specifically listed in the regulation, it is a hazardous waste.

Regulatory Level

(mg/L)

You also need to decide if it has any characteristics of a hazardous waste. Physical information on the MSDS may help you decide. If the flash point is below 60 °F (15 °C) or is classified by DOT as an oxidizer, the material may be ignitable. If the pH of the material is ≤2 or ≥12.5, the material may be corrosive. If the material is unstable, reacts violently with water, or may generate toxic gases, vapors, or fumes when mixed with water, it may be reactive.

SECTION III, continued

Use the chemical composition data to decide if a material is toxic. This decision is based on the concentration of certain contaminants (heavy metals and a number of organic compounds). If the waste is a liquid, compare the concentration of the contaminants in the liquid to the concentrations listed in 40 CFR 261.24. If the waste is a solid, analyze the sample by the Toxicity Characteristic Leachability Procedure (TCLP) and compare the results to the concentration listed in the 40 CFR 261.24. Levels above the threshold amount listed in the table are considered hazardous.

See the description of an MSDS (page 71) for help in finding information for making hazardous waste determinations.

Examples of Hazardous Waste

A number of chemicals used in and final solutions created from Hach procedures are hazardous wastes when they are disposed. In addition, substances in the sample matrix may be a hazardous waste. Sometimes, reagents which would be hazardous are neutralized or changed during the analytical procedure. In that case, the final solutions are not regulated. Finally, many reagents and final solutions may be non-regulated. The generator must either use their knowledge of the materials used or conduct analytical tests to determine if the final material is a hazardous waste.

Examples of tests using Hach reagents that generate hazardous waste include those containing mercury or mercury compounds such as COD tests or Nessler’s reagent. Conversely, a test using Hach reagents such as ManVer 2 Hardness Indicator Powder Pillows and EDTA Titration Cartridges does not produce a hazardous waste.

Hazardous Waste Disposal

Hazardous waste must be managed and disposed of according to federal, state, and local regulations. The waste generator is responsible for making hazardous waste determinations. Analysts should check with the facility’s environmental compliance people for specific instructions.

Hazardous wastes should be handled by treatment, storage, and disposal facilities (TSDF) that have USEPA permits. In some cases, the generator may treat the hazardous waste. In most cases, a permit from the USEPA is required to treat hazardous waste. Laboratories are not exempt from these regulations. If your facility is a “Conditionally Exempt Small Quantity Generator,” special rules may apply. Check 40 CFR 261 to determine if you have to comply with all the laws.

SECTION III, continued

The most common allowed treatment is elementary neutralization. This refers to neutralizing wastes that are hazardous only because they are corrosive or are listed only for that reason. Neutralize acidic solutions by adding a base such as sodium hydroxide; neutralize basic solutions by adding an acid such as hydrochloric acid. Slowly add the neutralizing agent while stirring. Monitor the pH. When it is at or near 7, the material is neutralized and may be flushed down the drain. Many wastes generated from Hach procedures may be treated in this manner.

Other chemical or physical treatments such as cyanide destruction or evaporation may require a permit. Check with your environmental department or local regulators to determine which rules apply to your facility.

Laboratory chemicals may be mixed and disposed of with other hazardous wastes generated at your facility. They may also be accumulated in accordance with 40 CFR 262.34 satellite accumulation rules. After collection they may be disposed of in a “labpack.” A number of environmental and hazardous waste companies offer labpacking services. They will inventory, sort, pack, and arrange proper disposal for hazardous waste. Find companies offering these services in the Yellow Pages under "Waste Disposal - Hazardous" or contact state and local regulators for assistance.

Management of Specific Wastes

Hach has several documents to assist customers in managing waste generated from our products. You can obtain the following documents by calling 1-800-227-4224 or 970-669-3050 and requesting the literature codes given:

Literature Code Title

1321 Waste Reduction: A Primer

9323 Mercury Waste Disposal Firms

9325 COD Waste Management

9326 COD Heavy Metal Total Concentrations

Special Considerations for Cyanide Containing Materials

Several procedures in this manual use reagents that contain cyanide compounds. These materials are regulated as reactive (D003) waste by the Federal RCRA. Waste disposal instructions provided with each procedure tell you how to collect these materials for proper disposal. It is imperative that these materials be handled safely to prevent the release of hydrogen cyanide gas (an extremely toxic material with the smell of bitter

SECTION III, continued

almonds). Most cyanide compounds are stable and can be safely stored for disposal in highly alkaline solutions (pH >11) such as 2 N sodium hydroxide. Never mix these wastes with other laboratory wastes that may contain lower pH materials such as acids or even water.

If a cyanide-containing compound is spilled, you must be careful not to be exposed to hydrogen cyanide gas. Take the following steps to destroy the cyanide compounds in an emergency:

a) Use a fume hood, supplied air or self-contained breathing apparatus.

b) While stirring, add the waste to a beaker containing a strong

solution of sodium hydroxide and either calcium hypochlorite or sodium hypochlorite (household bleach).

c) Add a lot of hydroxide and hypochlorite. Let the solution stand for

24 hours.

d) Neutralize the solution and flush it down the drain with a large

amount of water. If the solution contains other regulated materials such as chloroform or heavy metals, it may still need to be collected for hazardous waste disposal. Never flush hazardous wastes down the drain.

Resources

Many sources of information on proper waste management are available. The USEPA has a hotline number for questions about the Resource Conservation and Recovery Act (RCRA). The RCRA Hotline number is 1-800-424-9346. You may also get a copy of the appropriate regulations. Federal hazardous waste regulations are found in 40 CFR 260- 99. Obtain this book from the U.S. Government Printing Office or a number of other vendors. Other documents which may be helpful to the laboratory hazardous waste manager include:

1. Task Force on Laboratory Waste Management. Laboratory Waste

Management, A Guidebook; American Chemical Society, Department

of Government Relations and Science Policy: Washington, DC 1994.

2. Task Force on Laboratory Waste Management. Waste Management

Manual for Laboratory Personnel; American Chemical Society,

Department of Government Relations and Science Policy: Washington, DC 1990.

3. Task Force on Laboratory Waste Management. Less is Better; 2nd ed.;

American Chemical Society, Department of Government Relations and Science Policy: Washington, DC 1993.

SECTION III, continued

4. Committee on Chemical Safety. Safety in Academic Chemistry

Laboratories, 5th ed.; American Chemical Society: Washington, DC, 1990.

5. Armour, Margaret-Ann. Hazardous Laboratory Chemicals Disposal

Guide; CRC Press: Boca Raton, FL, 1991.

6. Environmental Health and Safety Manager’s Handbook; Government

Institutes, Inc.: Rockville, MD, 1988.

7. Lunn, G.; Sansone, E.B. Destruction of Hazardous Chemicals in the

Laboratory; John Wiley and Sons: New York, 1990.

8. National Research Council. Prudent Practices for Disposal of

Chemicals from Laboratories; National Academy Press: Washington,

DC, 1983.

9. National Research Council. Prudent Practices for Handling

Hazardous Chemicals in Laboratories; National Academy Press:

Washington, DC, 1981.

10. Environmental Protection Agency, Office of Solid Waste and

Emergency Response. The RCRA Orientation Manual; U.S. Government Printing Office: Washington, DC, 1991.

11. Environmental Protection Agency, Office of Solid Waste and

Emergency Response. Understanding the Small Quantity Generator Hazardous Waste Rules: A Handbook for Small Business; U.S. Government Printing Office: Washington, DC, 1986.

Material Safety Data Sheets

Material safety data sheets (MSDS) describe the hazards of chemical products. This section describes the information provided on a Hach MSDS and how to locate important information for safety and waste disposal. The information provided on the MSDS applies to the product as sold by Hach. The properties of any mixtures obtained by using this product will be different.

How to Obtain an MSDS

Hach ships a MSDS to each customer with the first order of any chemical product. A new MSDS may be sent when the information on the data sheet is updated. Please review all new MSDSs for new information. If you need another copy of an MSDS, simply call 1-800-227-4227.

SECTION III, continued

Sections of an MSDS

Each MSDS has ten sections. The sections and the information found in them are described below.

Header Information

The Hach catalog number, MSDS date, change number, company address and telephone number, and emergency telephone numbers are listed at the top of the MSDS.

1 Product Identification

This section contains:

• Hach product name

• Chemical Abstract Services (CAS) number

• Chemical name

• Chemical formula, if appropriate

• Chemical family to which the material belongs

2 Ingredients

This section lists each component in the product. It contains the following information for each component:·

• PCT: Percent by weight of this component

• CAS NO.: Chemical Abstract Services (CAS) registry number for

this component

• SARA: Superfund Amendments and Reauthorization Act, better

known as the “Community Right to Know Law.” Says if the component is listed in SARA 313. If the component is listed and you use more than the amount listed, you must report this to the USEPA every year.

• TLV: Threshold Limit Value. The maximum airborne concentration

for an 8 hour exposure that is recommended by the American Conference of Governmental Industrial Hygienists (ACGIH).

• PEL: Permissible Exposure Limit. The maximum airborne

concentration for an 8 hour exposure that is regulated by the Occupational Safety and Health Administration (OSHA).

• HAZARD: Physical and health hazards of the component

are explained.

SECTION III, continued

3 Physical Data

The physical properties of the product are given in this section. They include the physical state, color, odor, solubility, boiling point, melting point, specific gravity, pH, vapor density, evaporation rate, corrosivity, stability, and storage precautions.

4 Fire, Explosion Hazard And Reactivity Data

This section contains the flash point and flammable limits of the material. It also includes how to fight fires if the material catches on fire. Key terms in this section include:

• Flashpoint: The temperature at which a liquid will give off enough

flammable vapor to ignite.

• Flammability and ignitability are usually defined by the flash point.

• Lower Flammable Limit (LFL or LEL): The lowest concentration that

will produce a fire or flash when an ignition source is present.

• Upper Flammable Limit (UFL or UEL): The vapor concentration in

air above which the concentration is too rich to burn.

• NFPA Codes: The National Fire Protection Association (NFPA) has a

system to rate the degree of hazards presented by a chemical. These codes are usually placed in a colored diamond. The codes range from 0 for minimal hazard to 4 for extreme hazard. They are grouped into the following hazards: health (blue), flammability (red), reactivity (yellow), and special hazards (white).

5 Health Hazard Data

This section describes different ways the chemical can enter your body (ingestion, inhalation, skin contact). It also gives acute (immediate) and chronic (long-term) health effects. If the material causes cancer or genetic damage, it is identified in this section.

6 Precautionary Measures

This section contains special precautions for the material. These may include special storage instructions, handling instructions, conditions to avoid, and protective equipment required to use this material safely.

7 First Aid

First aid instructions for exposures to the chemical are given in this section. Be sure to read this section before inducing vomiting in a victim. Some chemicals are better treated by not inducing vomiting. Seek prompt medical attention for all chemical exposures.

SECTION III, continued

8 Spill And Disposal Procedures

This section tells about safe work practices for cleaning up and disposing of spilled material. Please refer to the Waste Management section of this manual. Final determination of proper and legal disposal options is the responsibility of the waste generator. Be sure you know the federal, state, and local laws that apply to your facility.

9 Transportation Data

Domestic and International shipping information is provided in this section. It gives shipping name, hazard class, and ID number of the product.

10 References

This section lists the reference materials used to write the MSDS.

Following the Reference section, the product is listed as having SARA 313 chemicals or California Proposition 65 List Chemicals, if applicable. Also found here is any special information about the product.

Safety

Safety is the responsibility of each person performing analytical procedures. Because many of the procedures in this methods manual use potentially hazardous chemicals and equipment, it is important to prevent accidents by practicing good laboratory techniques. The following guidelines apply to water analysis. These guidelines do not cover every aspect of safety, but they are important for preventing injuries.

Material Safety Data Sheet

A material safety data sheet (MSDS) comes with the first shipment of all products. The MSDS provides environmental and safety information about the products. Always read the MSDS before using a new product.

Reading Labels Carefully

Read each reagent label carefully. Pay particular attention to the precautions given. Never remove or block the label on a reagent container while it contains reagent. Do not put a different reagent into a labeled container without changing the label. When preparing a reagent or standard solution, label the container clearly. If a label is hard to read, re-label promptly according to your facility’s hazard communication program.

Warning labels also appear on some of the apparatus used with the test procedures. The protective shields with the COD Reactor and the Digesdahl Digestion Apparatus point out potential hazards. Be sure these shields are in place during use and observe the precautions on the label.

SECTION III, continued

Protective Equipment

Use the right protective equipment for the chemicals and procedures. The MSDS contains this information. Protective equipment may include:

• Eye protection such as safety glasses or goggles to protect from flying

objects or chemical splashes.

• Gloves to protect skin from toxic or corrosive materials, sharp

objects, very hot or very cold materials, or broken glass. Use tongs or finger cots when transferring hot apparatus.

• Laboratory coats or splash aprons to protect skin and clothing

from splashes.

• Footwear to protect feet from spills. Open toed shoes should not be

worn in chemistry settings.

• Respirators may be needed to protect you from breathing toxic vapors

if adequate ventilation, such as fume hoods, are not available.

• Use fume hoods as directed by the procedure or as recommended in

the MSDS.

• For many procedures, adequate ventilation is enough. Be sure there is

enough fresh air and air exhaust to protect against unnecessary exposure to chemicals.

First Aid Equipment and Supplies

Most first aid instructions for chemical splashes in eyes or on skin call for thorough flushing with water. Laboratories should have eyewash and shower stations. For field work, carry a portable eyewash unit. Laboratories should also have appropriate fire extinguishers and fume hoods.

General Safety Rules

Follow these rules to make work with toxic and hazardous chemicals safer:

1. Never pipet by mouth. Always use a mechanical pipet or pipet bulb to

avoid ingesting chemicals.

2. Follow test procedures carefully and observe all precautionary

measures. Read the entire procedure carefully before beginning.

SECTION III, continued

3. Wipe up all spills promptly. Get proper training and have the right

response equipment to clean up spills. See your safety director for more information.

4. Do not smoke, eat, or drink in an area where toxic or irritating

chemicals are used.

5. Use reagents and equipment only as directed in the test procedure.

6. Do not use damaged labware and broken equipment.

7. Minimize all chemical exposures. Do not breathe vapors or let

chemicals touch your skin. Wash your hands after using chemicals.

8. Keep work areas neat and clean.

9. Do not block exits or emergency equipment.

OSHA Chemical Hygiene Plan

The Occupational Safety and Health Administration (OSHA) enforces laws about the control exposure to hazardous chemicals in laboratories. These regulations are in Title 29 CFR 1910.1450. They apply to all employers who use hazardous chemicals. They require employers to develop and use a written Chemical Hygiene Plan and appoint a qualified person as the Chemical Hygiene Officer.

SECTION IV PROCEDURES

Method 8012

ALUMINUM (0 to 0.80 mg/L) For water and wastewater

Aluminon Method*

522 nm

1. Enter the stored

program number for aluminum (Al).

Press:

The display will show:

Note: The Pour-Thru Cell can be used if rinsed well with deionized water between the blank and prepared sample.

1 0 ENTER

Dial nm to 522

2. Rotate the

wavelength dial until the small display shows:

522 nm

When the correct wavelength is dialed in, the display will quickly show:

Zero Sample

then: mg/L Al

Note: Total aluminum determination needs a prior digestion; use any of the three procedures given in Digestion (Section II).

3. Fill a 50-mL

graduated mixing cylinder to the 50-mL mark with sample.

Note: Rinse cylinder with 1:1 Hydrochloric Acid and deionized water before use to avoid errors due to contaminants absorbed on the glass.

Note: The sample temperature must be between 20-25 °C (68-77 °F) for accurate results.

4. Add the contents of

one Ascorbic Acid Powder Pillow. Stopper. Invert several times to dissolve powder.

* Adapted from Standard Methods for the Examination of Water and Wastewater.

ALUMINUM, continued

:30

5. Add the contents of

one AluVer 3 Aluminum Reagent Powder Pillow. Stopper. Invert repeatedly for one minute to dissolve.

Note: A red-orange color develops if aluminum is present.

Note: Inconsistent results will be obtained if any powder is undissolved.

9. Press:

SHIFT TIMER

A 15-minute reaction period will begin.

When the timer beeps, the display will show:

mg/L Al

6. Pour 25 mL of

mixture into a 25-mL sample cell (the prepared sample).

10. Within five minutes

after the timer beeps, place the blank into the cell holder. Close the light shield.

7. Add contents of one

Bleaching 3 Reagent Powder Pillow to the remaining 25 mL in the mixing graduated cylinder. Stopper. Vigorously shake for 30 seconds.

Note: This solution should turn a light to medium orange upon bleaching. It will not become colorless.

11. Press: ZERO

The display will show:

Zeroing. . . .

then: 0.00 mg/L Al

8. Pour the remaining

25 mL of mixture in the cylinder into a second 25-mL sample cell (the blank).

12. Immediately place

the prepared sample into the cell holder. Close the light shield.

ALUMINUM, continued

Press: READ

13.

The display will show:

Reading. . . .

then the result in mg/L aluminum will be displayed.

Note: Clean the graduated cylinder and sample cells with soap and brush immediately following the test.

Note: For most accurate results, analyze a reagent blank (deionized water) and subtract the amount determined on each lot of reagents from the sample reading.

Sampling and Storage

Collect samples in a clean glass or plastic container. Preserve the sample by adjusting the pH to 2 or less with nitric acid (about 1.5 mL per liter). Preserved samples can be stored up to six months at room temperature. Before analysis, adjust the pH to 3.5–4.5 with 5.0 N Sodium Hydroxide. Correct the test result for volume additions; see Correcting for Volume Additions in Section I for more information.

ALUMINUM, continued

Accuracy Check

Standard Additions Method

a) Snap the neck off an Aluminum Voluette Ampule Standard

Solution, 50 mg/L as Al.

b) Use the TenSette Pipet to add 0.1 mL, 0.2 mL, and 0.3

mLof standard, respectively, to three fresh 50-mL samples. Mix each thoroughly.

c) Analyze each sample as described above. The aluminum

concentration should increase 0.1 mg/L for each 0.1 mL of standard added.

d) If these increases do not occur, see Standard Additions (Section I)

for more information.

Standard Solution Method

Prepare a 0.4-mg/L aluminum standard solution by pipetting 1.00 mL of Aluminum Standard Solution, 100 mg/L as Al volumetric flask. Dilute to the mark with deionized water. Prepare this solution immediately before use. Perform the aluminum procedure as described above. The mg/L Al reading in Step 13 should be 0.4 mg/L Al.

, into a 250-mL

Precision

Or, using the TenSette Pipet, add 0.8 mL of solution from an Aluminum Voluette Ampule Standard Solution (50 mg/L as Al) into a 100-mL volumetric flask. Dilute to volume with deionized water. Prepare this standard immediately before use.

In a single laboratory, using a standard solution of 0.2 mg/L Al and two representative lots of reagent with the DR/2010, a single operator obtained a standard deviation of ±0.016 mg/L Al

ALUMINUM, continued

Interferences

The following do not interfere up to the indicated concentrations.

Alkalinity 1000 mg/L as CaCO

Iron 20 mg/L

Phosphate 50 mg/L

Interferences from higher alkalinity concentrations can be eliminated by the following pretreatment:

a) Add one drop of m-Nitrophenol Indicator Solution to the sample

taken in Step 3. A yellow color indicates excessive alkalinity.

b) Add one drop of 5.25 N Sulfuric Acid Standard Solution.

Stopper the cylinder. Invert to mix. If the yellow color persists, repeat until the sample changes to colorless. Continue with the test.

Polyphosphate causes a negative interference at all levels and must be absent. Before testing, polyphosphate must be converted to orthophosphate by acid hydrolysis as described under the phosphorus procedures.

Acidity interferes at greater than 300 mg/L as CaCO greater than 300 mg/L acidity as CaCO

must be treated as follows:

. Samples with

a) Add one drop of m-Nitrophenol Indicator Solution to the sample

taken in Step 3.

b) Add one drop of 5.0 N Sodium Hydroxide Standard Solution.

Stopper the cylinder. Invert to mix. Repeat as often as necessary until the color changes from colorless to yellow.

c) Add one drop of Sulfuric Acid Standard Solution, 5.25 N, to

change the solution from yellow back to colorless. Continue with the test.

Calcium does not interfere.

Fluoride interferes at all levels by complexing with aluminum. The actual aluminum concentration can be determined using the Fluoride Interference Graph when the fluoride concentration is known. To use the fluoride interference graph:

ALUMINUM, continued

1. Select the vertical grid line along the top of the graph that represents

the aluminum reading obtained in Step 13.

2. Locate the point of the vertical line (DR/2010 reading) where it

intersects with the horizontal grid line that indicates how much fluoride is present in the sample.

3. Extrapolate the true aluminum concentration by following the

curved lines on either side of the intersect point down to the true aluminum concentration.

For example, if the aluminum test result was 0.7 mg/L Al fluoride present in the sample was 1.0 mg/L F grid line intersects with the 1.0 mg/L F and 1.3 mg/L Al curves. In this case, the true aluminum content would be

1.27 mg/L.

Fluoride Interference Graph

grid line falls between the 1.2

mg/L Al3+ (Reading from DR/2010)

, the point where the 0.7

and the

mg/L

Summary of Method

Aluminon indicator combines with aluminum in the sample to form a red-orange color. The intensity of color is proportional to the aluminum concentration. Ascorbic acid is added to remove iron interference. The AluVer 3 Aluminum Reagent, packaged in powder form shows exceptional stability and is applicable for fresh water samples.

True Aluminum concentration (mg/L Al3+)

ALUMINUM, continued

REQUIRED REAGENTS

Cat. No.

Aluminum Reagent Set (100 Tests) ..............................................................................22420-00

Includes: (4) 14290-99, (1) 14577-99, (1) 14294-49

Description Per Test Unit Cat. No.

AluVer 3 Aluminum Reagent Powder Pillow ......... 1 pillow............ 100/pkg..............14290-99

Ascorbic Acid Powder Pillow ................................. 1 pillow............ 100/pkg..............14577-99

Bleaching 3 Reagent Powder Pillow ....................... 1 pillow............ 100/pkg..............14294-49

REQUIRED APPARATUS

Cylinders, graduated mixing, 50 mL.................................. 1.................. each................1896-41

Sample Cell, 25 mL, matched pair..................................... 2 ................... pair..............20950-00

OPTIONAL REAGENTS

Aluminum Standard Solution, 100 mg/L...........................................100 mL..............14174-42

Aluminum Standard Solution, Voluette ampule,

50 mg/L as Al, 10 mL...................................................................... 16/pkg..............14792-10

Hydrochloric Acid Solution, 6N (1:1)................................................500 mL..................884-49

m-Nitrophenol Indicator Solution, 10 g/L..........................................100 mL................2476-32

Nitric Acid, ACS ................................................................................500 mL..................152-49

Nitric Acid Solution, 1:1.................................................................... 500 mL................2540-49

Sodium Hydroxide Standard Solution, 5.0 N...........................100 mL MDB................2450-32

Sodium Hydroxide Standard Solution, 5.0 N.............................50 mL MDB................2450-26

Sulfuric Acid Standard Solution, 5.25 N..................................100 mL MDB................2449-32

Water, deionized........................................................................................ 4 L..................272-56

Quantity Required

OPTIONAL APPARATUS

Ampule Breaker Kit ................................................................................ each..............21968-00

Brush ....................................................................................................... each..................690-00

Flask, volumetric, 100 mL ......................................................................each..................547-42

Flask, volumetric, 250 mL ......................................................................each..................547-46

Fluoride Combination Electrode ............................................................. each..............50265-00

pH Indicator Paper, 1 to 11 pH...................................................... 5 rolls/pkg..................391-33

pH Meter, sens

ion™1, portable............................................................. each..............51700-10

Pipet, TenSette, 0.1 to 1.0 mL ................................................................. each ..............19700-01

Pipet Tips, for 19700-01 TenSette Pipet ............................................. 50/pkg..............21856-96

Pour-Thru Cell Assembly Kit .................................................................each ..............45215-00

Thermometer, -20 to 105 °C....................................................................each................1877-01

For technical support and ordering information, see Section V.

In the U.S.A. call 800-227-4224 to place an order. Outside the U.S.A.—Contact the Hach office or distributor serving you.

Method 8326

ALUMINUM (0 to 0.220 mg/L) For water

Eriochrome Cyanine R Method*

535 nm

1. Enter the stored

program number for aluminum (Al), Eriochrome Cyanine R (ECR) method.

Press:

9 ENTER

The display will show:

Dial nm to 535

Note: The Pour-Thru Cell cannot be used.

5. Add the contents of

one ECR Reagent Powder Pillow. Stopper. Invert several times to dissolve powder, then wait 30 seconds.

2. Rotate the

wavelength dial until the small display shows:

535 nm

When the correct wavelength is dialed in, the display will quickly show:

Zero Sample

then: mg/L Al ECR

6. Add the contents of

one Hexamethylenetetramine Buffer Reagent Powder Pillow. Stopper. Invert several times to dissolve powder.

Note: An orange to purple color develops if aluminum is present.

3. Insert the 10-mL Cell

Riser into the cell compartment

7. Put 1 drop of ECR

Masking Reagent Solution into a 10-mL sample cell.

4. Fill a 25-mL

graduated mixing cylinder to the 20-mL mark with sample.

Note: Rinse cylinder with 1:1 hydrochloric acid and deionized water before use to avoid errors.

Note: The sample temperature must be 20-25 °C (68-77 °F).

8. Pour 10 mL from

the mixing graduated cylinder into the 10-mL sample cell. Swirl to mix (the blank.)

Note: The solution will start to turn yellow.

* Adapted from Standard Methods for the Examination of Water and Wastewater.

ALUMINUM, continued

9. Pour the remaining

10 mL of mixture into a second 10-mL sample cell to make the prepared sample.

13. Immediately place

the prepared sample into the cell holder. Close the light shield.

10. Press:

SHIFT TIMER

A 5-minute reaction period will begin.

When the timer beeps, the display will show:

mg/L Al ECR

14. Press: READ

The display will show:

Reading. . . .

11. Within five minutes

after the timer beeps, place the blank into the cell holder. Close the light shield.

12. Press: ZERO

The display will show:

Zeroing. . . .

then:

0.000 mg/L Al ECR

then the result in mg/L aluminum will be displayed.

Note: If fluoride (F-) is present, it needs to be measured and the actual value determined (see Table 2).

ALUMINUM, continued

Sampling and Storage

Collect samples in a clean glass or plastic container. Preserve samples by adjusting the pH to 2 or less with nitric acid (about 1.5 mL per liter). Preserved samples can be stored up to six months at room temperature. Before analysis, adjust the pH to 2.9 to 4.9 with 12.0 N Potassium Hydroxide Standard Solution and/or 1 N Potassium Hydroxide Solution. Correct the test result for volume additions; see Corrections for Volume Additions in Section I.

Accuracy Check

Standard Solution Method

Prepare a 0.100 mg/L aluminum standard solution by pipetting 1.00 mL of Aluminum Standard Solution, 100 mg/L as Al volumetric flask. Dilute to the mark with deionized water. Prepare this solution daily. Perform the aluminum procedure as described above. The mg/L Al should be 0.10 mg/L Al.

Or, using the TenSette pipet, add 0.2 mL of solution from an Aluminum Voluette Ampule Standard Solution (50 mg/L as Al) into a 100-mL volumetric flask. Dilute to volume with deionized water. Perform the aluminum procedure as described above. The mg/L Al reading should be

0.10 mg/L.

, into a 1000-mL

Method Performance

Precision

In a single laboratory, using a standard solution of 0.100 mg/L Al and two representative lots of reagent with the DR/2010, a single operator obtained a standard deviation of ±0.004 mg/L Al.

Interferences

Table 1 lists common interferences and the amount of interference that can be expected.

A sample pH between about 4.9 and 7.5 causes dissolved aluminum to partially convert to colloidal and insoluble forms. This method measures much of that hard-to-detect aluminum without any pH adjustment as is necessary in some other methods.

Polyphosphate interference can be reduced by converting polyphosphate to orthophosphate by the following steps:

a) Rinse a 50-mL mixing graduated cylinder and a 125-mL

erlenmeyer flask containing a magnetic stir bar with 6 N

ALUMINUM, continued

Hydrochloric Acid. Rinse again with deionized water. These rinses will remove any aluminum present.

Table 1 Interferences

Substance Concentration Error

Acidity 0-62 mg/L as CaCO

Alkalinity 0-750 mg/L as CaCO

0-1000 mg/L as CaCO

0-1000 mg/L 0%

0.2 mg/L -5% of reading

2 mg/L -5% of reading

0-4 mg/L + mg/L Fe2+ X 0.0075

0-4 mg/L + mg/L Fe3+ X 0.0075

see Table 2

Hexametaphosphate 0.1 mg/L as PO

0-1000 mg/L as CaCO

0-10 mg/L 0%

0-5 mg/L 0%

0-20 mg/L 0%

pH 2.9-4.9 0%

7.5-11.5 0%

(ortho) 4 mg/L -5% of reading

0-1000 mg/L 0%

0-10 mg/L 0%

-5% of reading

Note: Rinse two erlenmeyer flasks if a reagent blank is used; seeStepbbelow.

b) Measure 50 mL of deionized water into the 125-mL erlenmeyer

flask using the graduated cylinder. This is the reagent blank. Because of the test sensitivity, this step must be done only when any of the reagents used in the following pretreatment are replaced even if the new reagent has a matching lot number. When the pretreated sample has been analyzed, subtract the aluminum concentration of the reagent blank from the sample results.

c) Measure 50 mL of sample into the 125-mL erlenmeyer flask

using the graduated cylinder. Use a small amount of deionized water to rinse the cylinder contents into the flask.

ALUMINUM, continued

d) Add 4.0 mL of 5.25 N Sulfuric Acid Solution.

e) Use a combination hot plate/stirrer to stir and boil the sample for

at least 30 minutes. Add deionized water as needed to maintain a sample volume of 20-40 mL. Do not boil dry.

f) Cool the solution to near room temperature.

g) Add 2 drops of Bromphenol Blue Indicator Solution.

h) Add 1.5 mL of 12.0 N Potassium Hydroxide Standard Solution

using the calibrated, plastic dropper provided. Swirl to mix. The solution color should be yellow or green but not purple. If the color is purple, begin with Step a again using an additional 1 mL of Sulfuric Acid Solution in Step d.

i) While swirling the flask, add 1.0 N Potassium Hydroxide

Solution, a drop at a time, until the solution turns a dirty green color.

j) Pour the solution into the 50-mL graduated cylinder. Rinse the

flask contents into the graduated cylinder with deionized water to bring the total volume to 50 mL.

Fluoride interference can be corrected by using Table 2.

An Example: If the fluoride concentration is known to be 1.00 mg/L F and the ECR method gives a DR/2010 reading of 0.060 mg/L aluminum, what is the true mg/L aluminum concentration?

Answer: 0.183 mg/L

Intermediate values can be found by interpolation. Do not use correction graphs or charts found in other publications.

Summary of Method

Eriochrome cyanine R combines with aluminum in a sample to produce an orange-red color. The intensity of color is proportional to the aluminum concentration.

k) Use 20 mL this solution in Step 3 of the ECR method.

ALUMINUM, continued

Table 2 True aluminum concentration (mg/L) vs. DR/2010 reading (mg/L) and fluoride

concentration (mg/L) when the Eriochrome cyanine R method is used.

Fluoride Concentration (mg/L)

DR/2010

Reading

(mg/L)

0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

0.010 0.010 0.019 0.030 0.040 0.052 0.068 0.081 0.094 0.105 0.117 0.131

0.020 0.020 0.032 0.046 0.061 0.077 0.099 0.117 0.137 0.152 0.173 0.193

0.030 0.030 0.045 0.061 0.077 0.098 0.124 0.146 0.166 0.188 0.214 0.243

0.040 0.040 0.058 0.076 0.093 0.120 0.147 0.174 0.192 0.222

0.050 0.050 0.068 0.087 0.109 0.135 0.165 0.188 0.217

0.060 0.060 0.079 0.100 0.123 0.153 0.183 0.210 0.241

0.070 0.070 0.090 0.113 0.137 0.168 0.201 0.230

0.080 0.080 0.102 0.125 0.152 0.184 0.219

0.090 0.090 0.113 0.138 0.166 0.200 0.237

0.100 0.100 0.124 0.150 0.180 0.215

0.120 0.120 0.146 0.176 0.209 0.246

0.140 0.140 0.169 0.201 0.238

0.160 0.160 0.191 0.226

0.180 0.180 0.213

0.200 0.200 0.235

0.220 0.220

0.240 0.240

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

True Aluminum Concentration (mg/L) Al

REQUIRED REAGENTS

Cat No.

Aluminum Reagent Set (100 tests)............................................................................... 26037-00

Includes: (1) 26038-49, (2) 26039-46, (1) 23801-23

Description Per Test Unit Cat. No.

Quantity Required

ECR Reagent Powder ..............................................1 pillow ............100/pkg ............. 26038-49

Hexamethylenetetramine Buffer Reagent ...............1 pillow ............100/pkg ............. 26039-99

ECR Masking Reagent Solution............................... 1 drop .............. 25 mL ............. 23801-23

REQUIRED APPARATUS

Cell Riser, 10 mL sample cell.............................................1 ..................each .............45282-00

Cylinder, 25 mL, mixing graduated ....................................1 ..................each .............20886-40

Sample Cell, with 10-mL mark, matched pair....................2 ...................pair ............. 24954-02

ALUMINUM, continued

OPTIONAL REAGENTS

Description Unit Cat. No.

Aluminum Standard Solution, 100 mg/L...........................................100 mL..............14174-42

Aluminum Standard Solution, Voluette ampule,

50 mg/L as Al, 10 mL...................................................................... 16/pkg..............14792-10

Bromphenol Blue Indicator Solution .......................................100 mL MDB..............14552-32

Hydrochloric Acid Solution, 6 N (1:1)...............................................500 mL..................884-49

Nitric Acid, ACS ................................................................................500 mL..................152-49

Nitric Acid Solution, 1:1.................................................................... 500 mL................2540-49

Potassium Hydroxide Solution, 1 N ......................................... 50 mL SCDB..............23144-26

Potassium Hydroxide Standard Solution, 12.0 N...............................100 mL..................230-32

Potassium Hydroxide Standard Solution, 12.0 N...............................500 mL..................230-49

SPADNS Fluoride Reagent AccuVac Ampules .................................. 25/pkg..............25060-25

Sulfuric Acid Standard Solution, 5.25 N .................................100 mL MDB................2449-32

Water, deionized........................................................................................ 4 L..................272-56

OPTIONAL APPARATUS

Ampule Breaker Kit ................................................................................ each..............21968-00

Brush ....................................................................................................... each..................690-00

Cylinder, graduated, mixing, 50 mL ....................................................... each................1896-41

Flask, erlenmeyer, glass, 125 mL............................................................each..................505-43

Flask, volumetric, 100 mL ......................................................................each..............14574-42

Flask, volumetric, 1000 mL ....................................................................each..............14574-53

Fluoride Combination Electrode ............................................................. each..............50265-00

Hot Plate, Stirrer, 120 V ..........................................................................each..............23442-00

Hot Plate, Stirrer, 240 V ..........................................................................each..............23442-02

Pad, cooling, 4" x 4"................................................................................ each..............18376-00

pH Indicator Paper, 1 to 11 pH...................................................... 5 rolls/pkg..................391-33

pH Meter, sens

Pipet Filler, safety bulb............................................................................ each ..............14651-00

Pipet, serological, 2 mL........................................................................... each ..................532-36

Pipet, TenSette, 0.1 to 1.0 mL ................................................................. each ..............19700-01

Pipet Tips, for 19700-01 TenSette Pipet ............................................. 50/pkg..............21856-96

Pipet, volumetric, Class A, 1.00 mL ....................................................... each ..............14515-35

Pipet, volumetric, Class A, 4.00 mL ....................................................... each ..............14515-04

Stir Bar, Octagonal, 25.4 x 7.9 mm......................................................... each..............20953-52

Thermometer, -20 to 105 °C....................................................................each................1877-01

ion™1, portable............................................................. each..............51700-10

For technical support and ordering information, see Section V.

In the U.S.A. call 800-227-4224 to place an order. Outside the U.S.A.—Contact the Hach office or distributor serving you.

Method 8013

ARSENIC (0 to 0.200 mg/L) For water, wastewater, and seawater

Silver Diethyldithiocarbamate Method*

USEPA accepted for reporting (distillation required)**

520 nm

User

Calibration

1. This procedure

requires a user-entered calibration before sample measurement. See the steps in the User Calibration section to set up and calibrate a program for arsenic.

? ?

2. Enter the user stored

program number for arsenic (As).

9 ? ? ENTER

Press:

The display will show:

Dial to 520 nm

Note: The Pour-Thru Cell cannot be used.

3. Rotate the

wavelength dial until the small display shows:

520 nm

When the correct wavelength is dialed in the display will quickly show: Zero Sample

then: mg/L As

4. Prepare the Hach

distillation apparatus for arsenic recovery. Place it under a fume hood to vent toxic fumes.

Note: See the Hach Distillation Manual for assembly instructions.

Stir control: 5

Heat control: 0

5. Dampen a cotton ball

with 10% Lead Acetate Solution. Place it in the gas scrubber. Be certain the cotton seals against the glass.

* Adapted from Standard Methods for the Examination of Water and Wastewater. ** Equivalent to USEPA method 206.4 for wastewater and Standard Method 3500-As for drinking water.

6. Measure 25 mL

of prepared arsenic absorber solution into the cylinder/gas bubbler assembly with a graduated cylinder. Attach it to the distillation apparatus.

Note: Prepare the arsenic absorber solution as directed under Reagent Preparation below.

7. Measure 250 mL

of sample into the distillation flask using a graduated cylinder.

8. Turn on the power

switch. Set the stir control to 5. Set the heat control to 0.

ARSENIC, continued

9. Measure 25 mL of

hydrochloric acid, ACS, into the flask using a graduated cylinder.

13. When the timer

beeps, add 6.0 g of 20mesh zinc to the flask. Cap immediately.

10. Measure 1 mL of

Stannous Chloride Solution into the flask.

Note: Use a serological pipet to measure the solution.

Heat control: 3

14. Set the heat control

to 3.

Press:

SHIFT TIMER

A second 15-minute reaction period will begin.

11. Add 3 mL of

Potassium Iodide Solution to the flask. Cap.

Note: Use a serological pipet to measure the solution.

Heat control: 1

15. When the timer

beeps, set the heat control to 1.

SHIFT TIMER

Press:

A third 15-minute reaction period will begin.

12. Press: SHIFT TIMER

A 15-minute reaction period will begin.

Heat control: 0

16. When the timer

beeps, the display will show: mg/L As

Turn off the heater.

Remove the cylinder/gas bubbler assembly as a unit.

ARSENIC, continued

17. Rinse the gas

bubbler by moving it up and down in the arsenic absorber solution.

21. Pour the reacted

arsenic absorber solution into a sample cell (the prepared sample). Stopper.

Note: If the solution volume is less than 25 mL, add pyridine to bring the volume to exactly the 25-mL mark. Swirl to mix.

18. Fill a dry sample

cell with unreacted arsenic absorber solution (the blank). Stopper. Place it into the cell holder.

22. Place the prepared

sample into the cell holder. Close the light shield.

19. Place the blank

into the cell holder. Close the light shield.

23. Press: READ

The display will show:

Reading. . .

then the result in mg/L arsenic (As) will be displayed.

20. Press: ZERO

The display will show:

Zeroing. . .

then: 0.000 mg/L As

ARSENIC, continued

Sampling and Storage

Collect samples in acid washed glass or plastic bottles. Adjust the pH to 2 or less with sulfuric acid (about 2 mL per liter). Preserved samples may be stored up to six months at room temperature. Correct the test result for volume additions; see Correction for Volume Additions in Section I.

Reagent Preparation

Prepare the arsenic absorber solution as follows:

1. Weigh 1.00 g of silver diethyldithiocarbamate on an

analytical balance.

2. Transfer the powder to a 200-mL volumetric flask. Dilute to volume

with pyridine. (Use pyridine only in a fume hood.)

3. Mix well to dissolve. Store the reagent, tightly sealed, in an amber

bottle. The reagent is stable for one month if stored in this manner. Larger volumes of reagent can be prepared if the reagent is used within one month.

User Calibration

Standard Preparation

a) Prepare a 10.0-mg/L arsenic working standard by pipetting

1.00 mL of Arsenic Standard Solution, 1000 mg/L As, into a 100-mL volumetric flask. Dilute to volume with deionized water.

b) Prepare standards of 0.04, 0.08, 0.12, and 0.16 mg/L arsenic by

diluting 1.0, 2.0, 3.0, and 4.0 mL, respectively, of the working standard into four 250-mL volumetric flasks. Dilute to volume with deionized water.

Initial Setup of Arsenic Program

A one-time setup of a program for arsenic is required. An arsenic program template is pre-programmed into memory to make the process easier. After the setup is complete, the calibration can be entered for each new lot of reagents used or as necessary.

Note: The templates within User Program cannot be run directly. They

must be copied into a usable program number (greater than 950) as in ste c and d. Then, calibrate the program.

a) Press SHIFT USER PRGM. Use the UP arrow key to scroll to

Copy Program. Press ENTER.

ARSENIC, continued

b) Scroll to or enter the template number for arsenic (900).

c) Scroll to or enter the desired user program number for arsenic

ENTER.

Press

(>950). Press

ENTER. Record the program number for reference.

d) The display will show:

e) Press EXIT. The program is now ready to be calibrated.

User Calibration of Arsenic Program

a) Use the test procedure to develop color in the standards just

before recording the absorbance values for the calibration.

b) Press

SHIFT USER PRGM. Use the UP arrow to scroll to Edit

Program

. Press ENTER.

c) Scroll to or enter the program number for arsenic (from step c in

Setup). Press

d) Use the

DOWN arrow to scroll down to Calib Table:X (X= denotes

a number which indicates the number of data points in the table).

ENTER.

Press

e) The instrument will prompt

(unreacted arsenic absorber) in the cell holder. Close the light shield. Press the proper wavelength if necessary.

f) The first concentration point will be displayed. Press

display the stored absorbance value of the first concentration point.

Program Copied.

ENTER.

Zero Sample. Place the blank solution

ZERO. The instrument will prompt you to adjust to

ENTER to

g) Place the first developed standard solution (same concentration

as the value displayed) in the cell holder. Close the light shield.

READ to display the measured absorbance of the standard.

Press

ENTER to accept the displayed absorbance value.

Press

h) The second concentration point will be displayed. Press

ENTER to

display the stored absorbance value of the second concentration point. Place the second developed standard solution in the cell holder. Close the light shield. Press

READ to display the measured

absorbance value of the standard.

i) Press

ENTER to accept the absorbance reading. The next

concentration point will then be displayed.

ARSENIC, continued

j) Repeat steps h and i as necessary for the remaining standards.

k) When you are finished reading the absorbance values of the

l) Scroll down to Calib Formula. Press ENTER twice or until only

Note: Other calibration fits may be used if appropriate.

m) Press EXIT twice. The display will show Store Changes? Press

standards, press change the setting. Change to

ENTER.

press

0 in F(0) is flashing. Press DOWN arrow to select F1 (linear

the calibration). Press

ENTER to confirm.

EXIT. Scroll down to Force Zero. Press ENTER to

ON by pressing the arrow key, then

ENTER to select F1.

Interferences

Antimony salts may interfere with color development.

Summary of Method

Arsenic is reduced to arsine gas by a mixture of zinc, stannous chloride, potassium iodide and hydrochloric acid in a specially equipped distillation apparatus. The arsine is passed through a scrubber containing cotton saturated with lead acetate and then into an absorber tube containing silver diethyldithiocarbamate in pyridine. The arsenic reacts to form a red complex which is read colorimetrically. This procedure requires a manual calibration.

n) Press

EXIT. The program is now calibrated and ready for use. Start

on step 2 of the iconed procedure.

100

Hach DR2010 User manual

Specifications and Main Features

Frequently Asked Questions

User Manual

INTRODUCTION

SECTION I CHEMICAL ANALYSIS INFORMATION

SECTION II SAMPLE PRETREATMENT

SECTION III WASTE MANAGEMENT AND SAFETY

SECTION IV PROCEDURES

ALUMINUM (0 to 0.80 mg/L) For water and wastewater

ALUMINUM (0 to 0.220 mg/L) For water

ARSENIC (0 to 0.200 mg/L) For water, wastewater, and seawater