Hach DR/700 Procedures Manual

46014-88

DR/700

COLORIMETER

PROCEDURES MANUAL

©Hach Company, 1990-2001. All rights reserved. Printe d i n U .S.A. 7-30-96-9ed

Rev. 2b, 11/01

ii

TABLE OF CONTENTS

Introduction

Trademarks of Hach Company . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v

Sample Procedure Explained . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

Section I Chemical Analysis Information

Abbreviations and Conversions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1

Accuracy and Precision. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4

Standard Additions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4

USEPA Approved. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11

USEPA Accepted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11

Adapting Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-12

Adapting a Hach Procedure for Use With Other Photometers. . . 1 -12

Adapting a Buret Titration for Use With a Digital Titrator . . . . . 1-14

Interferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-17

pH Interference. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17

Interference from Stray Light. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-18

Laboratory Practice. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-18

Boiling Aids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-18

Filtration of Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-18

Reagent and Standard Stability . . . . . . . . . . . . . . . . . . . . . . . . . . 1-21

Reagent Blank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-21

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-22

Sample Cell Matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-23

Sample Dilution Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -24

Temperature Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-26

Use of Pipets and Graduated Cylinders . . . . . . . . . . . . . . . . . . . . 1-26

Use of AccuVac Ampuls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-27

Use of the DR/700 AccuVac Vial Adapter. . . . . . . . . . . . . . . . . . 1-27

Use of Reagent Powder Pillows. . . . . . . . . . . . . . . . . . . . . . . . . .1-29

Using PermaChem Pillows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-29

Using the TenSette Pipet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-30

Mixing Water Samples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-33

Volume Measurement Accuracy . . . . . . . . . . . . . . . . . . . . . . . . .1-34

Sample Pretreatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-35

Digestion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -35

Hach Digesdahl Digestion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-35

EPA Mild Digestion with Hot Plate . . . . . . . . . . . . . . . . . . . . . 1-35

EPA Vigorous Digestion with Hot Plate . . . . . . . . . . . . . . . . . .1-36

General Digesdahl Digestion Procedure. . . . . . . . . . . . . . . . . . 1 -38

Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-44

Application Specific Manuals . . . . . . . . . . . . . . . . . . . . . . . . . . .1-48

iii

CONTENTS, continued

Distillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-48

Sampling and Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-49

Taking Water Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-49

Acid Washing Bottles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -50

Storage and Preservation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-51

Volume Additions, Corrections for . . . . . . . . . . . . . . . . . . . . . . . 1 -55

Section II Procedures

DR/700 Filter Module Selection Guide . . . . . . . . . . . . . . . . . . . . . . . 2-1

Procedure Listing by Parameter (alphabetical) . . . . . . . . . . . . . . .2-1

Procedure Listing by Filter Module. . . . . . . . . . . . . . . . . . . . . . . .2-3

Listing by Filter Module

42.01. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42-1

45.01. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45-1

48.01. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48-1

50.01. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50-1

52.01. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52-1

55.01. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55-1

57.01. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57-1

61.01. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61-1

69.01. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69-1

81.01. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81-1

Section III Technical Support

Technical Training Workshops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1

Technical and Application Assistance. . . . . . . . . . . . . . . . . . . . . . . . . 3-1

Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2

Technical Publications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2

How to Order. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-11

Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13

Literature Request Form
Mail Order Form

iv

INTRODUCTION

This manual is divided into three sections:

Section I Chemical Analysis Information

This section relates to all of the procedures. It provides excellent
background information or review material for the technician or
chemist. Commonly-used procedure steps are explained in detail.

Section II Procedures

Step-by-step illustrated instructions for measuring approximately 100
different parameters or constituents are presented. The instrument is
factory calibrated and ready to use (e xcept for proce dure s requiring us er
calibration). Clearly written steps are supplemented with helpful notes.
Each procedure includes information on sampling and storage, checking
accuracy, adjusting for interferences and a listing of all the reagents and
apparatus needed to run the test. Additional information on the
chemical reactions of many of the procedures is contained in the Hach
Water Analysis Handbook, Publication 8353, available free on request.

Section III Technical Support

Technical support is provided to our customers in numerous ways as
described in the paragraphs in this section. Hach provides free training
workshops an d of fers publica tions on various areas of analysis, also free
of charge. A staff of trained specialists are on call to give individual
assistance via our 800 number throughout each working day

Before preceding to the analysis procedures in Section II, the
analyst should read the instrument manual to learn about the
DR/700 features and its operation.

Trademarks of Hach Company

AccuVac® Hach in Oval Design® PhosVer®
AluVer® Hach Logo® RoVer®
BariVer® Hach One® StannaVer®
BoroVer® HexaVer® StillVer®
CalVer® IncuTrol® SulfaVer®
ChromaVer® LeadTrak® Surface Scatter®
ColiQuick® ManVer® TanniVer®
CuVer® MercuVer® TenSette®
CyaniVer® MolyVer® TitraStir®
Digesdahl® Mug-O-Meter® TitraVer®
DithiVer® N-Trak® UniVer®
FerroVer® NitraVer® Voluette®
FerroZine® NitriVer® ZincoVer®
Gelex® PermaChem®

v

vi

SAMPLE PROCEDURE

Type of
samples
analyzed

Name of
method
used

Acceptance of
method by
USEPA if
applicable

Procedure
step

Procedure name

Range with
units of
measure

Procedure
identification
number

Method 8048

PHOSPHORUS, REACTIVE (0 to 2.50 mg/L PO

For water, wastewater, seawater

4

(also called: Orthophosphate) PhosVer 3 (Ascorbic Acid) Method*
(Powder Pillows or AccuVac Ampuls),
USEPA accepted for reporting**

USING POWDER PILLOWS

1. Install DR/700

module

81.01

in the instrument.

2. Press: l/O

The display will show

810 nm

and module number

81.01

3. After 2 seconds,

the display will show a
program number,
concentration units,
decimal position and
the zero prompt. If
necessary, press the

ARROW

key until the
lower display shows
program number

81.02.1

Instrument
display

3-

)

UP

Keystrokes
required

*Adapted from Standard Methods for the Examination of Water and Wastewater.
**Procedure is equivalent to USEPA method 365.2 and Standard Method 4500-P-E for wastewater.

81-47

Reference for
method used

vii

Additional
information
that may be
applicable

Illustration of
procedure steps
and instrume nt
keystrokes
required

PHOSPHORUS, REACTIVE, continued

4.

Fill a 10-mL cell to
the 10-mL line with
sample.

Note: For proof of
accuracy, use a 1.0 mg/L
Phosphate (0.33 mg/L P)
Standard Solution (listed
under Optional Reagents)
following these steps, in
place of the samp le.

Note: Run a reagent blank
for this test. Use deionized
water in place of the
sample in Step 4. Subtract
this result from all test
results run with this lot of
PhosVer.

Note: Optional 25-mL
reagents sample may be
used (see Optional
Reagents).

5. Add the contents of

one PhosVer 3
Phosphate Powder
Pillow to the sample
cell (the prepared
sample). Cap and
invert several times to
mix.

Note: A blue color will
form if phosphate is
present.

6. Wait two minutes.

Note: An 8-10 minute
reaction period should be
used if determining total
phosphate following the
acid-persulfate digestion.

Note: If the sample
temperature is less than

O

15
minutes of reaction time.

2 minutes

C (59 OC), allow 9

81-48

viii

PHOSPHORUS, REACTIVE, continued

Conversion
Factors
Table

7. Fill a 10-mL cell to

the 10-mL line with

8. Place the blank in

the cell holder.

sample (the blank).

Note: In bright
sunlight it may be
necessary to close the
cell compartment
cover.

10. Place the

11. Press: READ

prepared sample in the
cell holder.

Note: In bright sunlight it
may be necessary to clo s e
the cell compartment
cover.

To convert reading from To Multiply by

mg/L PO4 mg/L P2O5 0.747

mg/L PO

Tab l e 1. Conversion Factors

mg/L P 0.326

4

The display will count
down to 0. Then the
display will show the
results in mg/l
phosphate (as PO

Note: To convert results to
other units, see Table 1.

9. Press: ZERO

The display will count
down to 0 Then the
display will show 0.00
mg/l, and the zero
prompt will turn off.

).

4

81-49

ix

PHOSPHORUS, REACTIVE, continued

Alternate
method

USING ACCUVAC AMPULS

1. Install DR/700

module

81.01

in the instrument.

2. Press: l/O

The display will show
and module number

810 nm

81.01

3. After 2 seconds,

the display wi ll sho w a
program number,
concentr at ion un it s,
decimal position and
the zero prompt. If
necessary, press the

UP ARROW key until

the lower display
shows program
number

81.03.1

81-50

x

PHOSPHORUS, REACTIVE, continued

30 seconds

4. Fill a cell with 10

mL of sample (the
blank). Cap. Collect at
least 40 mL of sample
in a 50-mL beaker.

Note: Run a reagent blank
for this test. Use deionized
water in place of the
sample in Step 4. Subtract
this result from all test
results run with this lot of
PhosVer.

2 minutes

5. Fill a PhosVer 3

Phosphate AccuVac
Ampul with sample.

Note: Keep the tip
immersed while the ampul
fills completely.

7. Wait two minutes. 8. Place the blank in

the cell holder.

Note: In bright sunlight it
may be necessary to close
the cell compartment cov er.

6. Place an ampul cap
securely over the tip of
the ampul. Shake the
ampul for app roximately
30 seconds. Wipe off
any liquid and finger
prints.

Note: A blue color will
form if phosphate is
present.

Note: Accuracy is
unaffected by undissolved
powder.

9. Press: ZERO

The display will count
down to 0. Then the
display will show

0.0 mg/l, and the zero
prompt will turn off.

81-51

xi

PHOSPHORUS, REACTIVE, continued

10.

Insert the
AccuVac Vial Adapter
into the cell holder.

11. Place the

prepared sample in the
cell holder.

Note: In bright sunlight it
may be necessary to close
the cell compar tment co ver.

12. Press: READ

The display will count
down to 0. Then the
display will show the
results in mg/L
phosphate (as PO

Note: To convert results to
other units, see Tabl e 2.

).

4

If sample
cannot be
run
immediately,
follow these
steps

To convert reading from To Multiply by

mg/L PO4 mg/L P2O5 0.747
mg/L PO

Table 2. Con version Factors

mg/L P 0.326

4

SAMPLING AND STORAGE

Collect sample in plastic or glass bottles that have cleaned with 1:1
Hydrochloric Acid Solution and rinsed with deionized water. Do not use
commercial detergents containing phosphate for cleaning glassware used in
phosphate analysis.

Most reliable results are obtained when samples are analyzed as soon as
possible after collection. If prompt analysis is impossible, preserve samples
up to 24 hours by storing at or below 4 C. For longer storage periods, add 4.0
mL of Mercuric Chloride Solution to each liter of sample taken and mix.
Use of mercuric chloride is discouraged whenever possible for health and
environmental considerations. Sample refrigeration is still required.
Samples preserved with mercuric chloride must have a sodium chloride level
of 50 mg/L or more to prevent mercury interference. Samples low in
chloride should be spiked with 0.1 g sodium chloride per liter of sample.

81-52

xii

PHOSPHORUS, REACTIVE, continued

Confirm
accuracy with
these steps

In addition, may
also be used to
troubleshoot a
test, improve
technique, check
reagents and to
assure cleanliness
of glassware

Levels of
common sample
substances or
conditions that
will cause
inaccurate
results

ACCURACY CHECK

Standard Additions Method
a) Snap the neck off a Phosphate Voluette Ampule Standard Solution,

50 mg/L PO

-

.

4

b) Use the TenSette Pipet to add 0.1 mL, 0.2 mL and 0.3 mL of standard,
respectively, to three 25-mL water sample. Mix each thoroughly. (For
AccuVac Ampuls use 50-mL Beakers.)

c) Analyze each sample as described above. The phosphate concentration
should increase 0.2 mg/L for each 0.1 mL of standard added.

d) If these increases do not occur, see Standard Additions (Section 1 of the
DR/2000 Procedures manual or Water Analysis Handbook) for more
information.

INTERFERENCES

Large amounts of turbidity may cause inconsistent results in the phosphate
tests because the acid present in the powder pillow may dissolve some of the
suspended particles and because of variable desorption of orthophosphate
from the particles. for highly turbid or colored samples, add the contents of
one Phosphate Pretreatment Powder Pillow to 25 mL of sample. Mix well.
Use this solution to zero the instrument.

The PhosVer 3 Reagent Powder Pillows should be stored in a cool, dry
environment.

The following may interfere when present in concentrations exceeding these
listed below:

Copper 10 mg/L
Iron 100 mg/L
Silica 50 mg/L
Silicate 10 mg/L

Arsenate and hydrogen sulfide do interfere.

Highly buffered samples or extreme sample pH may exceed the buffering
capacity of the reagents and require sample pretreatment; see Interferences,
pH (Section 1).

81-53

xiii

PHOSPHORUS, REACTIVE, continued

Expected
repeatability
of the
procedure

Concise
explanation
of method

The amount
of reagents
and apparatus
needed to
perform the
procedure as
written

STATISTICAL EVALUATION

A single operator repetitively tested samples of two laboratory prepared
solutions, using one DR/700, matched sample cells and two representative
lots of testing reagents. Testing 1.60 mg/L PO
standard deviation was ±0.007 mg/L PO

Testing zero concentration samples, the limit of detection was 0.019 mg/L

3-

. The limit of detection was calculated as three times the standard

PO

4

3-

concentration samples, the

4

3-

.

4

deviation when testing zero concentration samples (Adapted from Analytical
Chemistry, 1980, 52, 2242-2249.

Using two representative lots of AccuVacs, the standard deviation was ±0.008
mg/L PO

3-

and the limit of detection was 0.021 mg/L PO

4

3-

.

4

SUMMARY OF METHOD

Orthophosphate reacts with molybdate in an acid medium to produce a
phosphomolybdate complex. Ascorbic acid then reduces the complex, giving
an intense molybdenum blue color.

REQUIRED REAGENTS (Using Powder Pillows)

Quantity

Description Per Test Unit Cat. No.

PhosVer 3 Phosphate Reagent

Powder Pillows . . . . . . . . . .1 Pillow . . . . .100/pkg . . . . . . . . 2125-99

REQUIRED REAGENTS (Using AccuVac Ampuls)

PhosVer 3 Phosphate Reagent

AccuVac Ampuls . . . . . . . . 1 ampul . . . . . .25/pkg . . . . . . . . . 25080-25

Items needed
to perform the
procedure, not
included with
the instrument

REQUIRED APPARATUS (Using Powder Pillows)

Clippers, for opening

powder pillows . . . . . . . . . . 1. . . . . . . . . . . .each . . . . . . . . . . . . . 968-00

DR/700 Filter Module

Number 81.01 . . . . . . . . . . .1. . . . . . . . . . . .each . . . . . . . . . . . 46281-00

REQUIRED APPARATUS (Using AccuVac Ampuls)

Beaker, 50 mL . . . . . . . . . . . . .1. . . . . . . . . . . .each . . . . . . . . . . . . . 500-41

Cap, ampul, blue . . . . . . . . . . . 1. . . . . . . . . . . .25/pkg . . . . . . . . . . 1731-25

DR/700 Filter Module

Number 81.01 . . . . . . . . . . .1. . . . . . . . . . . .each . . . . . . . . . . . 46281-00

81-54

xiv

Supplemental
reagents and
apparatus
mention ed in
the notes

PHOSPHORUS, REACTIVE, c ont inued

OPTIONAL REAGENTS

Description Unit Cat. No.

Hydrochloric Acid

Standard Solution, 6.0 N (1:1) . . . . . . . . . . . 500 mL . . . . . . . . . . 884-49

Mercuric Chloride Solution, 10 g/L . . . . . . . . . 100 mL . . . . . . . . 14994-42

Phosphate Pretreatment Powder Pillows . . . . . . 50/pkg . . . . . . . . . 14501-66

Phosphate Standard Solution,
1 mg/L as PO
Phosphate Standard Solution, Voluette ampul,
50 mg/L as PO
PhosVer 3 Phosphate Reagent

Powder Pillows, 25 mL sample. . . . . . . . . . . 100/pkg. . . . . . . . . 212 5-99

Sodium Chloride, ACS . . . . . . . . . . . . . . . . . . 454 g . . . . . . . . . . . . 182-01

Sodium Hydroxide

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

Water, deionized . . . . . . . . . . . . . . . . . . . . . . . 4 L . . . . . . . . . . . . . 272- 5 6

OPTIONAL APPARATUS

Adapter, AccuVac Vial, DR/700 . . . . . . . . . . . . each . . . . . . . . . . 43784-00

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

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

pH Meter, Hach One . . . . . . . . . . . . . . . . . . . . each . . . . . . . . . . 43800-00

Pipet, 2 mL serological . . . . . . . . . . . . . . . . . . each . . . . . . . . . . . . 532-36

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

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

Pipet Filler, safety bulb . . . . . . . . . . . . . . . . . . each . . . . . . . . . . 1465 1-00

Sample Cell, 10-mL with screw cap . . . . . . . . . 6/pkg . . . . . . . . . . 2427 6-06

Sample Cell, 25-mL with screw cap . . . . . . . . . 6/pkg . . . . . . . . . . 2401 9-06

Spoon, measuring, 0.1 g . . . . . . . . . . . . . . . . . each . . . . . . . . . . . . 511-00

. . . . . . . . . . . . . . . . . . . . . . . 500 mL . . . . . . . . . 2569-42

4

, 10 mL . . . . . . . . . . . . . . . . 16/pkg . . . . . . . . . . 171-10

4

For Technical Assistance, Prices and Ordering

In the U.S.A. - Call 800-227-4224 toll-free for more information.
Outside the U.S.A. - Contact the Hach office or distributor serving you.

*Larger sizes available.

81-55

xv

xvi

SECTION I Chemical Analysis Information

1-a

1-b

SECTION I CHEMICAL ANALYSIS INFORMATION

ABBREVIATIONS AND CONVERSIONS

Abbreviations

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

°C degree(s) Celsius (Centigrade)
°F degree(s) Fahrenheit
ACS American Chemical Society reagent grade purity
A/F Acid/fluoride extraction method for soils
APHA Standard Methods Standard Methods for the Examination of

Water and Wastewater, published jointly by the Amer ican Pub lic
Health Association (APHA), the American Water Works Association
(AWWA), and the Water Pollution Control Federation (WPCF).
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.

AV AccuVac
Bic bicarbonate extraction method for soils
Bicn bicinchoninate
conc concentrated
DB dropping bottle
F&T free and total
FTU Formazin Turbidity Units. Turbidity unit of measure based

on a Formazin stock suspension.

FV FerroVer
FZ FerroZine
g grams
gr/gal gr ains per gallon (1 gr/gal = 17.12 mg/L)
HR high range
kg/ha kilograms per hectare
Lbs/Ac pounds per acre
LR low range
MDB marked dropping bottle
mg/L milligrams per liter (ppm)
µg/L micrograms per liter (ppb)
ml or mL (milliliter)-approximately the same as a cubic centimeter
MR medium range
NPDWR National Primary Drinking Water Regulations
NPDES National Pollutant Discharge Elimination System
P plants
PV PhosVer
S soil
SCDB self-contained dropping bottle
TPTZ (2,4,6-Tri-(2-Pyridyl)-1,3,5-Triazine)
USEPA United States Environmental Protection Agency

1-1

Conversions

Conversion factors for many of the commonly used units of measure
have b een included to mak e the u se of this manual more uni v ers al and to
simplify calculations. Conversions are categorized by test.

Nitrogen

Nitrite (NO2) = Nitrogen (N) x 3.28
Nitrate (N0
Ammonia (NH
Ammonium (NH

) = Nitrogen (N) x 4.42

3

) = Nitrogen (N) x 1.22

3

) = Nitrogen (N) x 1.29

4

Phosphate

Phosphorus (P) = Phosphate (PO4) x 0.326
Phosphorus P e ntoxide (P

) = Phosphate (PO4) x 0.75

2O5

Table 1. Hardness Conversion

British American French German

gr/gal gr/gal parts/ parts/
Units of mg/l (Imperial ) (US) 100,000 100,000 lb./cu ft
Measure CaCO

CaCO3CaCO3 CaCO3CaO meq/L* g/L CaO CaCO

3

3

mg/L CaCO

1.0 0.07 0.058 0.1 0.056 0.02 5.6X10-46.23X10

3

English gr/gal
CaCO

3

14.3 1.0 0.83 1.43 0.8 0.286 8.0X10-38.91X10

US gr/gal
CaCO

3

17.1 1.2 1.0 1.72 0.96 0.343 9.66X10-31.07X10

Fr. p/100,000
CaCO

3

10.0 0.7 0.58 1.0 0.56 0.2 5.6X10-36.23X10

Ger. p/100,000

CaO 17.9 1.25 1.04 1.79 1.0 0.358 1.0

X10

-2

1.12X10

meq/L 50.0 3.5 2.9 5.0 2.8 1.0 2.8X10-23.11X10

g/l CaO 1,790.0 125.0 104.2 179.0 100.0 35.8 1.0 0.112

lb./cu ft CaCO

*or 'epm/L,' or 'mval/L'
N.B. 1 meq/L = N/1000

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

3

-5

-4

-3

-4

-3

-3

1-2

Oxygen, Dissolved

The following table lists the mg/L dissolved oxygen in water at
saturation for v arious temperatures an d atmospheric pressure s. The table
was formulated in a laboratory using pure water; thus, the values given
should be considered as only approximations when estimating the
oxygen content of a particular body of surface water.

Table 2. Dissolved Oxygen Saturation In Water

Pressure in Millimeters and Inches Hg

Temp 775 760 750 725 700 675 650 625 mm

°F °C 30.51 29.92 29.53 28.45 27.56 26.57 25.59 24.6 inches

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

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 5.8 5.6 5.4 5.2 5.0 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

1-3

A CCURACY AND PRECISION

Accuracy is the nearness of a test result to the true value. Precision refers
to the agreement of a set of replicate results or repeatability. Although
good precision suggests good accuracy, precise results can be
inaccurate. The following paragraphs describe techniques to improve
accuracy and precision of analysis.

Standard Additions

Standard additions is a widely accepted technique for checkin g the
validity of test results. Also known as "spiking" and "known additions,"
the technique also can be used to check the perfo rmance of th e r eagents ,
the instrument and apparatus, and the procedure.

Standard additi ons is perfo rmed by adding a small amount of a standard
solution containing a known amount of the component being measured
to an analyzed sample and repeating the analysis—using the same
reagent, instrument and technique. The amount of increase in the test
result should equal exactly the amount of component added.

For example, if testing shows a 25-mL water sample analyzed for iron
contains 1.0 mg/L, the result can be checked by adding 0.10 mL of a

50.0-mg/L iron standard solution to another 25-mL portion of the water
sample and repeating the analysis. The result of the analysis on the
second sample should be 1.2 mg/L iron because the standard added an
equivalent of 0.2 mg/L. For example:

0.10 mL x 50.0 mg/L
25 mL

= 0.2 mg/L

If 0.2 mg/L is recovered from the 0.2 mg/L addition, the analyst can
conclude the first answer was correct and the reagents, instrument and
method used are all working properly. Because the effect of incremental
volume additions is small, the sample volume used in the above equation
was 25 mL (not 2 5 + 0 .1). U sing 25 m L, i ns tead of 25.1 mL, represents
less than 0.4% error. For 0.3 mL standard addition, the error would be
less than 1.2% error.

If the second analysis does not give the correct amount of increase in the
iron content, it must be concluded the first answer also may be incorrect.
The analyst must determine why the technique did not work . The source
of the problem can be determined by using a logical troubleshooting

1-4

approach whether the fault lies in the reagent, the instrument and
apparatus, the test procedure or an interfering substance present in the
test sample. A decision tree, such as the one in Figure 1, estab lishes a
systematic method for identifying the problem. Request Hach
Publication 7004 for additional information on stan dard additions.
Explanations of the various steps follow.

Figure 1
Standard Additions
Decision Tree

Did a Single Standard Addition Give the Correct Recovery?

No

D

Is the Procedure in

Use Correct?

No

Use Correct

Procedure and

Repeat B

E

Are the Reagents Working Properly?

No

A

Are

Interferences

Present?

B

Standard Additions

Correct Recovery?

No

Do Multiple

On DI Water Give

Yes

Yes

C

Do Multiple Standard
Additions On Sample

Give Uniform Increments?

No

F

Analysis

Is Incorrect

Yes

G

Analysis May

be Correct

Yes

Yes

Yes

J

Are

Interferences

Present?

No

K

Analysis

Is Correct

No

Repeat B with
New Reagents

H

Is Instrument Apparatus Working Properly?

No Yes

Yes

I

Repair/Replace

Instrument Apparatus

and Repeat B

Standards Defective

Repeat B with New

1-5

Standards

Branch A

Suppose a single standard add ition to the samp le did not gi v e the cor rect
concentration increase. A possible cause could be interferences. Other
causes could be defective reagents, an incorrect procedure, a defective
instrument and apparatus or a defective standard used for standard
additions. 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:

1. Conduct an iron analysis on a 25.0-mL sample of deionized water.

2. Add 0.1 mL of a 50-mg/L iron standard solution to a second 25.0 -mL

sample of deionized water. Analyze this sample for iron.

3. Add 0.2 mL of a 50-mg /L iron standard soluti on to a third 25.0-mL
sample of deionized water. Analyze this sample for iron.

4. Add 0.3 of a 50-mg/L iron standard solution to a fourth 25.0-mL
sample of deionized water. Analyze this sample for iron.

5. Tabulate the data as shown below.

mL Std. mg/L Std. mg/L Iron

Added Added Found

00 0

0.1 0.2 0.2

0.2 0.4 0.4

0.3 0.6 0.6

The data shown above indicates several points upon which the following
conclusions may be made: First, the chemicals, instrument, procedures
and standards are working corr ectly because ir on added to the deion ized
water sample was recovered entirely in the same uniform steps of
addition. Second, because iron added to deionized water was reco vered,
but was not recovered when an addition was made to an actual water
sample (Branch A), the sample contains interferences which prev ent th e
test reagents from operating properly. Third, the first sample analysis
gave an incorrect result.

1-6

If the results of multiple standard additions gave the correct increments
between additions, proceed to Branch C. If the results of multiple
standard additions gave other than the correct increments between
additions, proceed to Branch D.

Branch C

If interfering ions are present, the analysis may be incorrect. Ho wev er , it
may be possible, with multiple standard additions, to arrive at a close
approximation of the correct result. Suppose the result of a sample
analyzed for iron was 1.0 mg/L. The analyst, knowing interfering ions
could be present , made on e stan dard add ition o f 0.1 m L of 50 -mg/L iron
standard to 25.0 mL of sample. Rather than finding an increase of

0.2 mg/L as expected, the analyst found an increase of 0.1 mg/L. The
analyst took a third and fourth water sample and added a standard
addition of 0.2 and 0.3 mL, respectively. Samples were analyzed and
results tabulated. If steps between each addition are roughly uniform
(i.e., 0.1 mg/L difference between each a ddition), proceed to Branch G.
If the results are not uniform (i.e., 0.1, 0.08, and 0.05 mg/L), proceed to
Branch F.

Branch D

Carefully check the instructions or directions for use of the test, making
sure the proper reagents are used in the proper order and time, the
colorimeter is adjusted for the correct wavelength and calibration and
the glassware in use is that specified. Be sure time for color
development and the sample temperature are exactly as specified. If the
procedure in use is found to be in error, repeat Branch B using the
correct procedure. If the procedure is found to be correct, proceed to
Branch E.

Branch E

Check the performance of the reagents. This may be done easily by
obtaining a new 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 or greater than the time required for the reagent
in question. If it is determined reagents are defective, repeat Branch B
with new reagents. If the reagents are p roven in g ood condition, proceed
with Branch H.

Branch H

Check operation of the instrument and/or apparatus used in the
performance of the test. Perform the wavelength and linearity checks

1-7

given in your instrument manual. Check glassware used in the
procedure, making sure that it is scrupulously clean. Dirty pipets and
graduated cylinders are sources of contamination and will not deliver the
correct volumes. Hach's TenSette Pipet for dispensing Standards and
standards sealed in Voluette Ampules are ideal for standard additions.

If a defect is found in the instrument and/or apparatus, repeat Branch B
after repair or replacement of the instrument and/or apparatus. If the
instrument and apparatus are foun d to be in good working order , pro ceed
with Branch I.

Branch I

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

Branch F

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

Example A:

mL Std. mg/L Std. mg/L

Added Added Found

00 1.0

0.1 0.2 1.10

0.2 0.4 1.18

0.3 0.6 1.23

Example B:

mL Std. mg/L Std. mg/L

Added Added Found

00 0

0.1 0.2 0

0.2 0.4 0.2

0.3 0.6 0.4

The two examples illustrate the effect of interferences on the standard
addition and on substances in the sample. Data plotted on the Fi gure 2

1-8

graph as A and B show that the four data points do not lie on a straight
line. Plot A illustrates an interference becoming progressively worse as
the concentration of the standard increases. This type of interference is
not common 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.

Plot B illustrates a common chemical interference which becomes less
or even zero as the concentration of the standard incr eases. The graph of
the example shows the first standard addition was consumed by the
interference and the remaining additions gave the correct incremental
increase of 0.2 mg/L.

Figure 2 Multiple Standard Additions Graph

1-9

The apparent interference in Example B could be the result of an error
made in the standard addition. The analysis should be repeated.

The two examples illustrate chemical interferences which most certainly
mean the result of the first analysis of the water sample was incorrect.
When this type of interference occurs, the analyst should attempt to
analyze the sample with an alternate method which uses a different type
of chemistry.

Branch G

Examples of uniform increments between standard additions are given
below .

Example C:

mL Std. mg/L Std. mg/L

Added Added Found

00 0.4

0.1 0.2 0.5

0.2 0.4 0.6

0.3 0.6 0.7

Plot C illustrates a common interference with a uniform effect upon the
standard and the substances in the sample. The four data points form a
straight line which may be extrapolated back through the horizontal
axis. The point intersection with the horizontal axis can be used to
determine the concentration of the substance in question. In the
example, the first analysis showed 0.4 mg/L. The result located
graphically should be much closer to the correct result: 0.8 mg/L.

Apparent interferences also may be caused by a defect in the ins trument
or the standards. Befor e assuming the interference is chemical in n ature,
check Branch B.

Example D:

mL Std. mg/L Std. mg/L

Added Added Found

00 0

0.1 0.2 0.2

0.2 0.4 0.4

0.3 0.6 0.6

1-10

Plot D illustrates a problem for the analyst. Increments found are
uniform and the recovery of the standard was complete. The result of
the first analysis was 0 mg/L and the graph plots back through 0 mg/L.
If interferences are kno wn to be present, the interfer ence may be pres ent
in an amount equal to the substance in question, thereby preventing the
analyst from finding the substance. This would be an uncommon
situation.

Branch J

If the standard addition gives the correct result, the analyst must then
determine if interfering substances are present. If interfering substances
are not present, the result of the analysis prior to the standard addition is
correct. If interfering substances are present, proceed to Branch C.

One of the greatest aids to the analyst is knowledge of the sample's
composition. An analyst need not know the exact composition of each
sample but should be aware of potential interferences in the method of
analysis to be used. When performing a particular method, the analyst
should know if those interferences are present or not in order to have
confidence in the accuracy of the results.

USEPA Approved

The United States Environmental Protection Agency (USEPA)
establishes limits for maximum contamination levels for certain
constituents in water. They also require 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
APHA
of Water and Wastewater), ASTM

1

, AWWA2 and WCPF3 (Standard Methods for the Examination

4

, USGS5 and AOAC6. All USEPA-

approved methods are cited in the Federal Register and compiled in the

Code of Fe deral Regulations.

USEPA Accepted

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

1-11

ADAPTING PROCED URES

ADAPTING HACH PROCEDURES FOR USE WITH OTHER
PHOTOMETERS

Hach test procedures can be used with other instrumentation if
calibration curves are established to convert test results from %
transmittance or absorbance to the concentration of the constituent being
measured. Regardless of the instrument used, the sample and
standardizing solutions are prepared the same way and the optimum
wavelength specified in these procedures applies to testing with other
spectrophotometers. In the example below, a sample calibration for iron
concentrations of 0 to 2.4 mg/L is described. A series of iron standard
solutions are prepared and measured to establish the calibration curve.
The readings are plotted on semilogarithmic paper as % transmittance
vs. concentration (or absorbance vs. concentration on linear-linear
paper). Points on the graph shown (Figure 3) are connected with a
smooth curve and the curve is used to make the calibration table if
desired. The proced ure follows:

1. Prepare several known concentrations with values covering the
expected range. At least five standards are recommended. Run tests on
25-mL samples as described in the procedure. Then pour the customary
volume of each known solution into separate, clean sample cells of the
type specified for your instrument.

2. Select the proper wavelength and standardize the instrument using
untreated sample water or a reagent blank as specified by the test
procedure.

3. Measure each of the known solutions and plot the % transmittance
readings on semilogarithmic graph paper as % transmittance vs.
concentration. Plot the % transmittance values on the logarithmic
(vertical) scale and the concentration values on the linear (horizontal)
scale. In the following example, iron standard solutions of 0.1, 0.2, 0.4,

0.8, 1.2, 1.6 and 2 mg/L were measured on a Spectronic 20
Spectrophotometer at 500 nm. Half-inch test tubes were used. Results
were plotted as shown on the graph (Figure 3) and the calibration table
values (Table 3) were extrapolated from the curve.

To convert transmittance readings to mg/L iron, use Table 3 and select
the appropriate line from the "% T Tens" column and the appropriate
column from the "% T Units" group of columns. For example, if the

1-12

instrument reading was 46%, the 40 line and the 6 column would be
selected. The test result would be 0.78 mg/L iron (Fe).

If in Step 3, absorbance values are measured, plot the results on linear­linear paper. Plot the absorbance value on the vertical scale and the
concentration values on the horizontal scale. Increasing absorbance
values are pl otted from bottom to top and increasing concentration
values are plotted from left to right. Values of 0.000 absorbance and 0
concentration will both begin in the bottom left corner of the graph. A
calibration table can be extrapolated from the curve or concentration
values and read directly from the curve in the graph.

Figure 3 Calibration Curve Example

1-13

Table 3 Calibration Table

%T %T UNITS
Tens 0123456789

0
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 .99 .97 .94
40 .92.89.87.84.82.80.78.77.73.71
50 .69.67.65.64.62.60.58.56.55.53
60 .51.49.48.46.45.43.42.40.39.37
70 .36.34.33.32.30.29.28.26.25.24
80 .22.21.20.19.17.16.15.14.13.12
90 .11.09.08.07.06.05.04.03.02.01

Adapting a Buret Titration for Use With a Digital Titrator

Adapt any standard titration procedure using a buret to the Digital
Titrator by using the following procedure.

1. Select a titration cartridge from Table 4 with the same active
ingredient as the buret solution.

2. Determine the approximate number of digits required. The Digital
Titrator dispenses 1 mL per 800 digits on the counter. Using the
following equation, determine the digits required for your buret method.

Digits Required =

x mL

t

x 800

t

N

c

N

Where:

N

= Normality of buret Titration

t

mL

= milliliters of buret titrant required for an average titration

t

N

= Normality of Digital Titrator cartridge

c

3. If the number of digits required is within the range of 70 to 350, you
can use the procedure as written, substituting the Digital Titrator directly
for the buret. Or, if the number of digits is outside of this range, make
the following modifications.

a. If the number of digits required is more than 350, reduce the sample
size to save titrant.

1-14

b. If the number of digits required is less th an 70 , increase th e sample

size to increase precision.
c. If the sample size is altered, adjust the amount of buffering or
indicating reagents by the same proportion.

4. When using the Digital Titrator for your buret method, note the
number of digits required for a sample titration. To convert the digits
required to the equivalent number of milliliters in the buret method was
used, calculate:

N

Equivalent Buret Milliliters = Digits Required x

c

800 x N

t

If the sample size was changed, adjust the equivalent buret milliliters
accordingly. If the sample size was increased, reduce the equivalent
buret milliliters; if the sample size was reduced, increase the equivalent
buret milliliters. Multiply the equivalent milliliters by any normally
used factors to calculate concentration in oz/gal, g/L, etc.
Example: Adapt a buret procedure which normally requires about 20
mL of a 0.4 N titrant to the Digital Titrator. Try a 8.0 N titration
cartridge. The first equation above gives:

Digits Required =

0.4 x 20 x 800

8.0

= 800 digits

Because this would use excessive titrant, reduce the sample size to one­fourth its normal size to reduce the digits required to 200, well within
the recommended range.

Upon completion of the titration using the smaller sample size, calculate
the equivalent buret milliliters by the second equation above. If 205
were the digits required:

Equivalent Buret Milliliters =

205 x 8.0
800 x 0.4

= 5.13 mL

Multiply the 5.13 mL by four to account for the reduction in sample size
to give the true equivalent buret milliliters of 20.5 mL. If the buret
method called for multiplying the number of milliliters of titran t by a
factor to calculate the concentration of a sample component, then
multiply 20.5 by that factor.

1-15

Table 4. Titration Cartridges

Description Cat. No.

CDTA, 0.0800 M, HexaVer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14402-01

CDTA, 0.800 M, HexaVer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14403-01

Ceric Standard Solution, 0.5 N . . . . . . . . . . . . . . . . . . . . . . . . . . .2270 7-01

EDTA, 0.0499 M. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2125 3-01

EDTA, 0.0800 M, TitraVer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14364-01

EDTA, 0.142 M. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1496 0-01

EDTA, 0.714 M. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1495 9-01

EDTA, 0.800 M, TitraVer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1439 9-01

FEAS, ferrous ethylenediammonium sulfate, 0.00564 N. . . . . . . . . .22923-01

Hydrochloric Acid, 8.00 N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14390-01

Iodate-Iodide, potassium, 0.3998 N. . . . . . . . . . . . . . . . . . . . . . . .14961-01

Iodate-Iodide, potassium, 1.00 N. . . . . . . . . . . . . . . . . . . . . . . . . .2294 4-01

Magnesium Chloride, 0.0800 N. . . . . . . . . . . . . . . . . . . . . . . . . . .20625-01

Mercuric Nitrate, 0.2256 N. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14393-01

Mercuric Nitrate, 2.256 N. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .921-01

PAO, phenylarsine oxide, 0.00451 N . . . . . . . . . . . . . . . . . . . . . . .22599-01

PAO, phenylarsine oxide, 0.0451 N . . . . . . . . . . . . . . . . . . . . . . . .21420-01

Potassium Dichromate, 1.00 N . . . . . . . . . . . . . . . . . . . . . . . . . . .21971-01

Potassium Thiocyanate, 1.00 N. . . . . . . . . . . . . . . . . . . . . . . . . . .22959-01

Silver Nitrate, 0.2256 N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14396-01

Silver Nitrate, 1.128 N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14397-01

Sodium Hydroxide, 0.1600 N. . . . . . . . . . . . . . . . . . . . . . . . . . . . .14377-01

Sodium Hydroxide, 0.3636 N. . . . . . . . . . . . . . . . . . . . . . . . . . . . .14378-01

Sodium Hydroxide, 0.9274 N. . . . . . . . . . . . . . . . . . . . . . . . . . . . .14842-01

Sodium Hydroxide, 1.600 N. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14379-01

Sodium Hydroxide, 3.636 N. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14380-01

Sodium Hydroxide, 8.00 N. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14381-01

Sodium Thiosulfate, Stabilized, 0.02256 N . . . . . . . . . . . . . . . . . .24091-01

Sodium Thiosulfate, 0.113 N . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2267 3-01

Sodium Thiosulfate, 0.2000 N . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2267 5-01

Sodium Thiosulfate, 0.2068. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22676-01

Sodium Thiosulfate, 2.00 N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1440 1-01

Sodium Vanadate, 0.25 N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22949-01

Sulfuric Acid, 0.1600 N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14388-01

Sulfuric Acid, 1.600 N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14389-01

Sulfuric Acid, 8.00 N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14391-01

INTERFERENCES

Many analytical determinations are subject to interference from
substances that may be present in the sample. Most common
interferences are mentioned either in the test procedures or in the
accompanying notes. Our reagent formulations eliminate many
interferences and others are removed by special sample pretreatments
described in the procedure.

1-16

Interference also may be caused by a high concentration of the constituent
under analysis. For example, the presen ce o f a larger excess of chlor in e
will cause the test to r ead less tha n fu ll sca le. Dilution of the sample to
5 mg/L will result in a reading higher than f ull scale . Th is in dicates the
need for more dilution u ntil th e in strume nt re ad ing is "o n scale. "

When an unusual answer is obtained, a color other than that expected is
formed, or an unusual odor or turbidity is noticed, the result is suspect.
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 identical, the
original result probably is in error and an additional dilution sh ould be
made to check the second test (first dilutio n). This process is repeated
until the same corrected result is obtained on two successive dilutions.

More complete information about interferences and methods to
overcome them is contained in the General Introduction Section of
APHA Standard Methods. The analyst is urged to obtain this book and
refer to it when problems are encountered.

pH Interference

Many of the procedures in this manual are pH dependent. Hach reagents
contain built-in buffers to adjust the pH of the typical sample to the
correct pH range. However, the reagent buffer capacity may not be
suff icien t for some unus ual sample s. This occur s most of ten with high ly
buffered samples or samples with extreme sample pH. Check for pH
interference in the following manner:

1. From the Sampling and Storage section of your procedure determine
the optimum pH range of the test. This is the pH the preserved sample is
adjusted to just before running the test. For some procedures this
information may not be given. If the pH of your sample is within the
optimum pH range, buffering is not needed.

2. Measure the pH of your analyzed sample with a pH meter.

3. 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.

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

1-17

5. Compare the pH values of your analyzed sample with the reagent

blank.

6. If there is no differen ce in th e pH 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.

7. If there is a significant difference between the values of yo ur analyzed
sample and the reagent blank, adjust the sample pH to within the
optimum pH test range, or if none is given, to the value of the reagent
blank before analysis on all future determinations. Use the appropriate
acid, usually nitric acid, to lower the pH, and use the appropriate base,
usually sodium hydroxide, to raise the pH.

8. Analyze the sample as before.

Interference From Stray Light

Typical indoor lighting permits the DR/700 to operate with the cell
compartment cover open. In bright sunlight, it may be necessary to
close the cell compartment cover. If a 25-mL cell is used in the
procedure, transfer 10 mL of the solution to a 10-mL cell. If the 10-mL
cell is used for the blank, another 10-mL cell must be used for the
sample.

LABORATORY PRACTICE

Boiling Aids

Boiling is included as a necessary step in some procedures. It may be
conv enient to use a boiling aid such as boiling chips, Cat. No. 14835-31,
to reduce bumping. Bumping is caused by the sudden, almost explos i v e
conv ersion of w ater to steam as it is heated . Bumping may cause sam ple
loss or a hazardous condition and should be avoided.

All boiling aids used should be checked to verify they will not
contaminate the sample. Boiling aids (e xcept glass beads) shou ld not be
used again. Loosely covering the sample during boiling will prevent
splashing, reduce the possibility of contamination and minimize sample
loss.

Filtration of Samples

Filtering is the process of separating particles from the sample by using
a medium, generally filter paper, to retain particles but allow the

1-18

solution to pass through. This is especially helpful when sam ple
turbidity interferes with calorimetric analysis. Two general methods of
filtration are gravity and vacuum. Gravity filtration uses the force of
gravity to pull the sample though the filter paper. Vacuum filtration uses
the pressure difference created by either an aspirator or vacuum pump
plus the force of gravity to move the sample through the filter. Vacuum
filtration is faster than gravity filtration. Vacuum filter (see Figure 4) as
follows:

1. Place a filter paper into the filter holder.

2. Place the filter holder assembly in the filtering flask and 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 to
another container.

Figure 4 Vacuum Filtration

1-19

REQUIRED APPARATUS

Description Unit Cat. No.

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

Filter Holder, membrane . . . . . . . . . . . . . . . .each . . . . . . . . . . . 2340-00

Flask, filter, 1000 mL . . . . . . . . . . . . . . . . . .each . . . . . . . . . . . .546-53

Many of the procedures in this manual may be filtered with gravity
filtration. The only labware required is filter paper, a conical funnel and
a receiving flask. This labware is included under the Optional
Apparatus listing for each procedure. Gravity filtration provides better
retention of fine particles. For optimum filtering speed, add solution
until the filter paper cone is three-fourths filled. Never fill the cone
completely. Gr avity filter (see Figure 5) 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 5 Gravity Filtration

1-20

REQUIRED APPARATUS

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

The determination of metals requires acid and heat to pretreat the
sample. Because filter paper will disintegrate under these conditions,
vacuum filtration with glass fiber filter discs is recommended. Also,
glass filter discs do not retain colored species as filter paper would.

Reagent and Standard Stability

Most chemicals and prepared reagents do not deteriorate after
manufacture, but storage conditions and packaging have a great
influence on their stability. Absorption of moisture, carbon dioxide or
other gases from the atmosphere, bacterial action, or light (with
photosensitive compounds) may affect the reagent shelf life. In some
cases reaction with the storage container or interaction of reagent
components may occur.

Hach strives continually to prepare stable formulations and devise ways
of packaging them to provide maximum protection. Many unique Hach
formulations, metho ds of anal ys i s and forms of packaging have resulted
from these challenges.

Chemicals supplied by Hach have an indefinitely long shelf life when
stored under average room conditions, unless designated otherwise.
Notations on product labels specify any special storage conditions
required. Otherwise, reagents should be stored in a cool, dry, dark place
for maximum life. It is always good practice to date chemicals upon
receipt and rotate supplies so the older supplies are used first. If in
doubt about the reagent shelf life, run a standard to check reagent
effectiveness.

Reagent Blank

The term "reagent blank" refers to that portion of the test result
contributed solely by the reagent and not the sample. This portion of the
test result represents a positive error. In several of the tests, the reagent
blank is of such magnitude that compensation must be made each time

1-21

the test is performed. This is done by zeroing the instrument on
deionized water and reagents.

In most cases, the reagent blank is so small the instrument is zeroed on
either an untreated portion of the original water sample or deionized
water. This is done routinely without any significant loss of accuracy
except where extremely small amounts of a constituent are sought. In
such a case, it is best to determine the reagent blank by performing the
test on a sample of high-quality, turbidity-free deionized water. The
result is expressed in the concentration units of the test and is subtracted
from the test results of subsequent samples using that particular lot of
reagent. It is necessary to determine the reagen t blank only at first use
and at intervals of several months unless subsequent contamination is
suspected.

Every ef fort is made to produce reagents with the lowest possible blank.
In most cases, it is less than 0.009 absorbance units. In some instances,
it is either impossible or not practical to produce reagents with such a
low blank. In these cases, it is best to determine the reagent blank as
explained above and subtract it from each determination. A note is
included in the appropriate procedures describing when this is
necessary.

Safety

Safety is the responsibility of each individual when performing analysis
procedures, and the analyst must develop and maintain good safety
habits. Because many of the procedures in this methods manual requ ire
the use of potentially hazardous chemicals and apparatus, it is important
for the indi vidual con ductin g them to minimize chances for accidents by
practicing good laboratory techniques. Several rules applying to water
analysis in the laboratory and in the field follow. They are not all
inclusive, but they emphasize practices that often are key factors in
personal injury incidents.

Read Labels Carefully: Each reagent label should be read carefully
with particular attention paid to the precautionary information. Never
remove the label from 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, be sure to label
the container clearly.

1-22

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 they
recommend.

Wear Protective Clothing: Protective clothing should be worn when
handling chemicals that cause irritation or burns. When caustic
materials are being used, ey e protection, in particular, is important to
guard against spattering and splashes from accidental spills.

Use tongs or finger cots when transferring hot apparatus.

Use Mechanical Pipettors: Never pipet by mouth. Mouth pipetting
could result in accidentally ingesting a dangerous chemical. Make a
habit of using mechanical pipetting devices for all pipetting. Mistakes
that could cause serious injury will be avoided.

Use Special Care With Dangerous Chemicals and Apparatus:
Follow the test procedure steps carefully and observe all precautionary
measures. It is good practice to read the entire procedure carefully
before beginning the procedure. Use the safety equipment—such as
pipet fillers, protective clothing and ventilating hoods—appropriate for
the test being conducted. Wipe up all spills promptly. Do not smoke or
eat in an area where toxic or irritating chemicals are used. Use reagents
and apparatus only as they were meant to be used and use them only as
directed in the test procedure. Damaged labware and malfunctioning
equipment should not be used.

If accidental skin contact with hazardous chemicals occurs, flush the
contacted area with water for 15 minutes. Call a physician if necessary.
A MSDS (Material Safety Data Sheet) accompanies the first shipment of
all products. Refer to the MSDS for safety data essential for day-to-day
operations and safety training.

Sample Cell Matching

The sample cells provided with the DR/700 Colorimeter are not
optically perfect. Glass imperfections can introduce an error in the true
absorbance or percent transmittance measurement. In turn, the true
Absorbance or % T error can result in reduced accuracy. For optimum

1-23

accuracy and precision, sample cells should be matched prior to use.
Refer to Matching Sample Cells in the instrument manual supplied with
the colorimeter .

Sample Dilution Techniques

Ten and Twenty-five milliliter (mL) are the specified volumes for most
colorimetric tests. However, in some tests, the color d eveloped in the
sample may be too intense to be measured. Unexpected colors may
develop in other tests. In both cases, it is necessary to dilute the sample
or determine if interfering substances are present.

For examp le, when p erfor ming the chro mium tests, the colorimeter may
detect a concentration above the maximum range limit. This results in a
flashing maximum concentration value in the display. A sample
solution is necessary. The test can be repeated, for example, with a 25­mL graduated cylinder filled to the 5-mL mark with the sample and then
to the 10-mL mark with deionized water. Because the sample was
diluted to twice its original volume (5 mL to 10 mL), the test result
should be multiplied by 2 to give the correct concentration of chr omium .

T o accomplish the s ample dilution con veniently, pipet the chosen sample
portion into a clean graduated cylinder (or clean volumetric flask for
more accurate work) and f ill the cylinder (or f lask) to the desired v olume
with deionized water. Mix well. Use the diluted sample when running
the test.

As an aid, Table 5 shows the amount of sample taken, the amount of
deionized water used to bring th e volume up to 25 mL and the
multiplication factor.

Table 5. Sample Dilutions

Sample Deionized Water Used
Volume to Bring the Volume Multiplication
(mL) to 25 mL (mL) Factor

25.0 0.0 1

12.5 12.5 2

10.0* 15.0 2.5

5.0* 20.0 5

2.5* 22.5 10

1.0* 24.0 25

0.250* 24.75 100

*For sample sizes of 10 mL or less, a pipet should be used to measure the sample into the
graduated cylinder or volumetric flask.

1-24

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

An example: A 2.5 mL sample w as diluted w ith 22.5 m L of deio niz ed
water . The result was 0.35 mg/L. What is the concentration of the sample?

0.35 x 10 = 3.5 mg/L

More accurate dilutions can be done with a pipet and a 100-mL
volumetric flask. Pipet the sample and dilute to volume with deionized
water. I nvert several times to mix.

Table 6. Multiplication fact ors t o be us ed when sa mple is diluted

to 100 mL

Sample Volume (mL) Multiplication Factor

1100
250

520
10 10
25 4
50 2

Sample dilution also influences the level at which a substance may
interfere. The effect of the interferences decreases as the sample size
decreases. Therefore, the effect of the interference described in the
procedure notes will decrease as the sample size decreases. In other
words, higher levels of an interfering substance can be present if the
sample is diluted.

An example: Copper doe s not int erf ere 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 o f w ater, what is the level at which copper will not interfere?

Total Volume

Sample Volume

25

12.5

Interference

100 x 2 = 200 mg/L

= 2

level

= Dilution Factor

Dilution

x

factor

Interference level

=

in sample

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

1-25

Temperature Considerations

For best results, most tests described in this manual should be performed
with sample temperatures between 20 °C (68 °F) and 25 °C (77 °F). If
certain tests require closer temperature control, that requirement will be
indicated in notes following those procedures.

Use of Pipets and Graduated Cylinders

When small sample quantities are used, the accuracy of measurements is
important. Figure 6 illustrates the proper way of reading the sample lev el
or the meniscus formed when th e li quid wets the cylinder or pipet w a lls.

Figure 6 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 are long tubes with a series of calibrated marks to
indicate the volume of liquid delivered by the pipet. The calibrated
marks may extend to the tip of the pipet or may be only on the straight
portion o f the tube. Fill serologic al pipets to the zero mar k and
discharge the sample by allowing the sample to drain until the meniscus
is level with the desired mark. If the serological pipet has calibrated
marks extended to the tip of the pipet, the sample must be blown out of
the tip for accurate sample measurements.

1-26

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

Use of AccuVac Ampuls

AccuVac ampuls contain pre-measured reagent in optical-quality glass
ampuls. The sample is collected in a beaker or other open container. The
ampul tip is immersed stem first well below the sample surface and the
tip is broken of f (s ee Figure 7). The break mu st b e fa r enou gh below the
surface to prevent air from being drawn in as the level of the sample
lowers. The ampul is inverted several times to dissolve the reagent
powder (capping is unnecessary). Test results are not affected by
undissolved powder. Wipe the ampul with a towel to remove
fingerprints, etc. Insert the ampul into the AccuVac adapter into the
colorimeter sample compartment and read the results directly.

Figure 7 Using AccuVac Ampuls

Use of the DR/700 AccuVac Vial Adapter

For safety and ease of use, the DR/700 AccuVac Vial Adapter is
provided with the instrument for use with Hach Company's AccuVac
Ampul Reagents. Insert the adapter in the cell compartment by aligning

1-27

it about 1/4 inch out from the slot in the front side of the cell holder as in
Figure 8. Push the adapter against the slot sides to seat it. to be sure the
adapter is seated, gently slide it upward. The adapter should stop about
half way up and stay there.

For measurements, leave the adapter in the up position a nd insert an
AccuVac Ampul in the cell holder (see Figure 9). Taking care to avoid
sharp edges, gently push the ampule down until it stops. This centers
the ampul in the light path. Pushing down on the ampul will not fully
seat it. To remove the ampul, pull the adapter up with the side tabs, then
pull the ampul out.

The adapter should be removed before testing with round sample cells to
allow alignment with the mark on the cells with the tab on the cell
holder. To remove the adapter, tilt the top toward the front of the
instrument and then pull upwards.

Figure 8 Inserting AccuVac Vial Adapter

Figure 9 Inserting AccuVac Ampul

1-28

Use of Reagent Powder Pillows

Dry powdered reagen ts are used when p ossible to minimize pr oblems of
leakage and deterioration. Powders are packaged in individual, pre­measured, polyethylene "powder pillows." E ach pillo w contains enough
reagent for one test and is opened easily with nail clippers or scissors;
see Figure 10.

Figure 10 Opening Powder Pillows

Using PermaChem Pillows

For best results, slightly tap the pillow on a hard surface to collect the
powdered reagent in the bottom. Then:

1. Tear across, from A to B, holding the pillow away from your face.

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

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

procedure according to the instructions.

1. TEAR

AB

Figure 11 Using PermaChem Pillows

2. PUSH 3. POUR

1-29

Using the TenSette Pipet

For best results, al wa ys use a n e w tip for each pipetting operation . After
being used several times, the pipet tip may retain some liquid, causing
an error in delivery, Each pipet is supplied with 100 tips. Order Hach
replacements, for best results.

Always use careful and 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. The metering turret also
may be lightly coated with grease. Refer to the manual supplied with the

TenSette Pipet for more information.

For best accuracy, both the room temperature and the solution being
pipetted should be between 20 and 25°C. Avoid palming the pipet an
unnecessarily long time prior to u se because the aliquot v olume cou ld be
affected by elevated temperatures.

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

Operating Instructions

1. Attach a clean tip. Holding the T enSette i n one hand, gently pres s the

tip onto the tapered nose of the pipet until the tip is held firmly and a
good seal is obtained.

2. Turn the turret cap to align the desired volume on the vo lume-s etting
ring with the mark on the housing assembly.

1-30

3. Press down on the turret cap with the thumb, using a smooth motion,

until the turret reaches the stop. Immerse the tip about 5 mm (¼") belo w
the surface of the solution to avoid drawing air into the tip. 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 to
the extended position. Do not let the turret snap into place, or the
delivery volume may be affected.

5. With the turret up, withdraw the tip from the liquid and move it to
the receiving vessel. Avoid placing pressure on the cap while moving
the pipet.

1-31

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

position on the volume-setting ring to assure full blowout and
quantitative transfer of the sample. The "F" position provides full
blowout for the 1.0-mL setting.

7. With the tip in contact with the side of the receiving vessel, slowly
and smoothly press down on the cap until the turret reaches the stop and
the solution is completely discharged.

1-32

Mixing Water Samples

The following two methods may be helpful in tests that require mixing
sample with chemicals (usually in di cated by "swirl to mix" i nstructions).

1. A swirling motion is recommended when mixing sample in a
graduated cylinder or a titration flask. In this case, grip the cylinder (or
flask) firmly with the tips of three fingers; see Figure 12. Hold the
cylinder at a 45-degree angle and twist the wrist. This motion will move
the cylinder in an approximately 12-inch circle, giving the liquids an
intense rotation to accomplish complete mixing in a few turns.

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 simp l e but take a bit of practice in order
to obtain the best results.

2. When mixing sample in a square sample cell, th e swirlin g motio n is
attained by a simple twisting motion; see Figur e 13. Grasp the neck of the
cell with the thumb and inde x f inger of one hand whil e resting th e conca v e
bottom of the cell on the tip of the index finger of other hand. Rotate the
cell quickly, first one way and then the other, to mix the sample.

Figure 12 Swirling Graduated Cylinder

1-33

Figure 13 Swirling Square Mixing Bottle

Volume Measurement Accuracy

Sample cells supplied with the colorimeter are marked to indicate
approximately 10 mL or 10, 20, and 25 mL. In mos t tes ts where volume
measurements are critical, the procedure specifies the appropriate method.

If a sample must be diluted, use a pipet for volume measurement.
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 measurement of a 1.0-mL samp le produces a 10 %
error in the test result.

1-34

SAMPLE PRETREATMENT

Digestion

Digestion, required in several procedures, refers to the use of acid and
heat to break down a substance into components that can be analyzed.
This section has three different digestion procedures.

The Hach Diges dahl system is a n abso lute process that yields a digest
suitable for the determinatio n of metals, total p hosphorus and total kj eldahl
nitrogen (TKN). It is r ap id an d convenient. It is the meth od of cho ice.

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

Hach Digesdahl Digestion

In this procedure (pages 38-42) 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 analyses using
colorimetric method, see Procedures (Section II).

EPA Mild Dige stio n 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 (HCI).

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 fil tered 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.

1-35

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.

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 app ropriate sample v olume (see table belo w) into a beaker
and add 3 mL of concentrated redistilled nitric acid.

3. Place the beaker on a hot plate and e vaporate 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 in appearance with continued refluxing).

6. Again, evaporate to dryness (do not bake) and cool the beaker. If any
residue or precipitate results from the e vaporation, add redistilled 1:1
hydrochloric acid (5 mL per 100 mL of f inal v olume). See Table 7 below .

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 7 below for the size of flask.

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

1-36

result by the correction factor in column 5 of the table below. A reagent
blank also should be carried through the digestion and measurement
procedures.

Table 7. Vigorous Digestion

Expected Suggested Suggested Suggested Correction
Metal Sample for V olume Final Volume Factor
Concentration Digestion 1:1 HC1 After Digestion

1 mg/L 50 mL 10 mL 200 mL 4
10 5 10 200 40
100 1 25 500 500

1-37

GENERA L DIGESDAHL DIGE STION

1. Transfer a

preweighed or a
premeasured amount
of sample into a
100-mL volumetric
flask; see Table 8.
The amount
transferred should not
contain more than 0.5
g of solids or organic
liquids. The
maximum volume for
water samples is 50
mL. In samples with
more than 1% solids
present, use the
formula below:

Water
Sample

Volume

(mL)

Example: If solids are
10% of total volume of
sample, the maximum
volume of liquid sample
would be 5 mL.

Note: Several 50-mL
sample aliquots of the
sample may be digested
in succession to
concentrate a sample.

Note: If liquid is too
viscous to measure,
preweigh the sample
into the digestion flask.

=

50

% solids

2. Add concentrated

sulfuric acid according
to Table 8 to the
volumetric flask and
two or more silicon
carbide (Carborundum)
boiling chips for liquid
samples.

Note: Boiling chips can
be pretreated by soaking
in 1:1 nitric acid and
rinsing tho roughly with
deionized water.
Treat m ent may be
particularly important
in low level work.
Silicon carbide boiling
chips are recommended.

Note: Use only Hach
digestion flasks.
Volumetric flasks with
concave bottom should

not be used.

Warning
A safety shield placed
between the operator
and the Digesdahl is
required. Safety glassed
are mandatory.

Caution
Experimentation w it h
the Digesdahl Apparatus
is not recomm ended. See
Saf e t y Cons ideratio ns
following these steps.

3. Turn on th e w ater

to the aspirator and
make sure there is
suction to the
fractionating column.
T urn the temperature
dial to a heat setting of
440 °C (825 °F). For
meat digestion, set to
468 °C (875 °F).

Note: Wait for the
proper temperature to
be reached before
sample is place d on the
heater.

Note
Specific meth o d
manuals for a variety of
sample types are
available, free of charge
from Hach Company.
See Applicatio n ­Specific Manuals
following these steps for
a complete listing. New
methods are continually
being developed. Please
contact Hach Company
World Headquarters,
[phone], for a
current listing.

1-38

GENERAL DIGES D AHL DI GESTION, continued

3 - 5 minutes

4. Place the flask

weight followed by the
fractionating column
with funnel on the
flask. Place the flas k
on the heater and heat
until the boiling point
of sulfuric acid is
reached (refluxing
sulfuric acid will be
visible).

Note: White acid vapors
usually will be present
but their presence alone
does not indicate that the
boiling point of sulfuric
acid has been reached.

Note: Liquid samples
require total evaporation
of water before vapors
are visible.

5. Heat 3-5 minutes.

Do not boil sample to
dryness.

Note: Discard sample if
it evaporates to dryness
and use larger amount
of concentrate d sulfuric
acid for digestion in
Step 2.

Note: Some organic
samples may need more
than five minutes for
complex digestion. See
Table 8.

6. Be sure you have

added the correct
amount of sulfuric
acid. Add 10 mL of
50% hydrogen
peroxide to the
charred sample via
the funnel on the
fractionating head.

Note: If the digest does
not turn colorless, add
5 mL increments of
peroxide until the digest
becomes clear.

Note: Visually confirm
the presence of sulfuric
acid in the flask before
adding hydrogen
peroxide.

Note: If sample starts to
foam up into the neck of
the flask, lower
temperature to 335 °C
(600 °F). Continue
heating at lower
temperature until all
water is evaporated off.
Then r e tu rn to o rig in a l
digest io n temp er at ure.

If foaming or bumping is not stopped by lowering temperature or volume, then
liquid samples t hat will not clog the capillary fu nnel may be added to the flask
via the capillary funnel, 10 mL at a time. Decrease amount added if foaming
still persists.

Note

1-39

GENERAL DIGES D AHL DI GESTION, continued

7. Boil off excess

hydrogen peroxide by
heating for one more
minute after addition
of hydrogen pero xi de
is complete. Do not
heat to dryness.

Note: If the sample goes
to dryness, turn off the
Digesdahl and cool
completely. Add water
to flask before handling.
Repeat digestion from
the beginning.

8. Take the flask off

the heater and allow
the flask to cool.
Remove the
fractionating column
from the digestion
flask.

Note: Use finger cots to
remove the digestion
flask. Place it on a
cooling pad for at least
one minute. Then
remove the column.

REQUIRED REAGENTS

Quantity

Description Per Digestion Unit Cat. No.

Hydrogen Peroxide, 50%. . . . . 10 mL . . . . . . . 500 mL . . . . .21196-49

Potassium Hydroxide

Standard Solution, 1 N . . . varies. . . . . . . . 59 SCDB*. . .23144-26

Potassium Hydroxide

Standard Solution, 8 N . . . . varies . . . . . . . . 500 mL . . . . . . . 282 -49

Sulfuric Acid, ACS (concentrated,

specific gravity 1.84) . . . . .≥3 mL . . . . . . . 4 kg . . . . . . . . . .979-09

Water, deionized . . . . . . . . . . . varies . . . . . . . . 3.78 L . . . . . . . .272-17

REQUIRED APPARATUS

Dispenser, pour-out, 10 mL. . . 1. . . . . . . . . . . . each. . . . . . . .22200-38

Pipet, serological, 10 mL. . . . . 1. . . . . . . . . . . . each. . . . . . . . . .532-38

Pipet Filler, safety bu lb . . . . . . 1. . . . . . . . . . . . each. . . . . . . . 14651-00

Boiling Chips,

silicon carbide. . . . . . . . . . .varies. . . . . . . . 500 g . . . . . . .20557-34

1-40

GENERAL DIGES D AHL DI GESTION, continued

REQUIRED APPARATUS (continued)

Quantity

Description Per Digestion Unit Cat. No.

Safety Glasses . . . . . . . . . . . . . 1 . . . . . . . . . . . each. . . . . . . . 18421-00

Safety Shield, for Digesdahl . . 1 . . . . . . . . . . . each. . . . . . . .20974-00

Select one based on available voltage:

Digesdahl Apparatus,

115 Vac. . . . . . . . . . . . . . . . 1 . . . . . . . . . . . each. . . . . . . . 23130-20

Digesdahl Apparatus,

230 Vac. . . . . . . . . . . . . . . . 1 . . . . . . . . . . . each. . . . . . . . 23130-21

OPTIONAL REAGENTS

Kjeldahl Reduction Reagent

(for fluid fertilizers) . . . . . . . . . . . . . . . . . . 40 g. . . . . . . . 23653-04

2,4-Dinitrophenol Indicator Solution . . . . . . . . . .100 mL MDB . .1348-32

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

Potassium Hydroxide, 1 N . . . . . . . . . . . . . . . . .59 mL MDB . .23144-26

Sodium Hydroxide, 5 N . . . . . . . . . . . . . . . . . . .59 mL* SC D B. .2450-26

Sodium Hydroxide, 1 N . . . . . . . . . . . . . . . . . . . . 100 mL* MDB. .1045-32

Hydrogen Peroxide, 30% . . . . . . . . . . . . . . . . 500 mL . . . . . . . 144-49

OPTIONAL APPARATUS

Balance, Sartorius, B310S, 110 V. . . . . . . . . . . each. . . . . . . . 24030-00

Balance, Sartorius, B310S, 220 V. . . . . . . . . . . each. . . . . . . . 24030-02

Beaker, 400 mL . . . . . . . . . . . . . . . . . . . . . . . . each. . . . . . . . . .500-48

Beaker, Berzelius, 200 mL . . . . . . . . . . . . . . . 12/pkg. . . . . . 22761-75

Bottle, Wash, 1 L. . . . . . . . . . . . . . . . . . . . . . . each . . . . . . . . . . 620-16

Bulb, dropper, 2 mL . . . . . . . . . . . . . . . . . . . . 12/pkg. . . . . . 21189-00

Cylinder, graduated, 50 mL. . . . . . . . . . . . . . . each. . . . . . . . . . 508-41

Dispenser, 1-5 mL, (for H
Dispenser, 10-50 mL, (for H

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

Filter Holder, membrane . . . . . . . . . . . . . . . . . each. . . . . . . . . 2340-00

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

Flask, flat-bottom volumetric, 100 mL . . . . . . . each. . . . . . . . 23125-42

Fume Scrubber Apparatus, 115 V. . . . . . . . . . . each. . . . . . . . 23266-00

Fume Scrubber Apparatus, 230 V. . . . . . . . . . . each. . . . . . . . 23266-02

Oven, laboratory, 120 V . . . . . . . . . . . . . . . . . each. . . . . . . .14289-00

Paper, weighing, 76 x 76 mm . . . . . . . . . . . . . 500/pkg. . . . . 14738-00

pH Paper, pH 1-11. . . . . . . . . . . . . . . . . . . . . . 5 roll/pkg . . . . . 391-33

, meat). . . . . . . . each. . . . . . . .23121-37

2SO4

, meat). . . . . . each. . . . . . . . 23121-41

2SO4

1-41

GENERAL DIGES D AHL DI GESTION, continued

OPTIONAL APPARATUS (continued)

Description Unit Cat. No.

pH Meter, EC10, Portable . . . . . . . . . . . . . . . each. . . . . . . . 50050-00

Pipet, Pasteur, disposable, 229 mm. . . . . . . . . . 250/pkg. . . . . 21234-01

Safety Glasses . . . . . . . . . . . . . . . . . . . . . . . . . each. . . . . . . . 18421-00

Spatula, stainless, 127 mm . . . . . . . . . . . . . . . each. . . . . . . . . .561-64

Spoon, measuring, 0.05 g . . . . . . . . . . . . . . . . each. . . . . . . . . .492-00

Stir Bar, PTFE, 1" . . . . . . . . . . . . . . . . . . . . . . each . . . . . . . . 20953-51

Stir Plate, magnetic, Thermolyne,

120V, 50/60 Hz. . . . . . . . . . . . . . . . . . . . . . each. . . . . . . . 23444-00

Stir Plate, magnetic, Thermolyne,

240V, 50/60 Hz. . . . . . . . . . . . . . . . . . . . . . each. . . . . . . . 23444-02

Stopper, hollow size #5 . . . . . . . . . . . . . . . . . . 6/pkg. . . . . . . 14480-05

Syringe, 5 mL, plastic . . . . . . . . . . . . . . . . . . . 100/pkg. . . . . 23433-33

Watch Glass, 65 mm . . . . . . . . . . . . . . . . . . . . 12/pkg. . . . . . . . 578-97

For additional ordering information, see final section.
In the U.S.A. call 800-227-422 4 to place an order.

*Contact Hach for larger siz es.

1-42

Table 8. Digestion Guidelines for Specific Sample Types

Sample Sample Amount Preheat Amount of Special
T ype W e ight of Acid Time Pero xi de Instructions

Plant 0.25 to 5 g 4 mL 4 min. 10 mL Use N-free paper
Tissue to weigh sample

Meat & 0.5 g or 4 mL or as 4 min. 10 mL May use
Poultry predigestion in predigest predigestion

procedure; see

Systems for Food,
Feed and
Beverage Analysis

(Lit. Code 3120.)

Fluid 0.1 to 0.25 g 4 mL 4 min. 10 mL Add 0.4 g Kjeldahl
Fertilizers Reduction Powder

to flask before
adding sulfuric
acid. Place the
flask in an 80 °C
oven 15 minutes
before digestion.
Use N-free paper to
weigh sample

Feed & 0.25 g 4 mL 4 min. 10 mL Use N-free
Forage paper to weigh

sample

Dairy 0.25 to 2.0 g 4 mL 4 min. 10 mL Use N-free paper

to weigh dry
samples (cheese)

Cereal 0.25 to 0.5 g 4 mL 4 min. 10 mL Use N-free paper to

weigh sample

Beverage approx. 5 g 4 mL 1 min. 10 mL Preheat acid for 1

(pipet into minute then add
funnel) sample through

funnel. Heat flask
30 seconds after
sample is in flask.

Sludge < 2.5 g wet 4 mL 3 to 10 mL or Heat the diluted

sludge 5 min. increase in digest for 15
< 0.5 g dried 5 mL minutes and filter.
sludge increments

Water & not more than 3 mL until acid 10 mL or Water must
Waste- 0.5 g solid is refluxing increase in evaporate bef ore
water (mL = 50/C; 5 mL acid will reflux.

C = % solids) increments Boiling chips

required.

Bath 0.3 to 10 mL 4 mL 4 minutes 10 mL Water must
Solutions e vapor ate before

acid will reflux.

Boiling chips

required.

1-43

Table 8. Digestion Guidelines for Specific Sample Types (continued)

Sample Sample Amount Preheat Amount of Special
T ype Weight of Acid Time Perox ide Instructions

Edible 0.25 to 0.5 g 4-6 mL 4 min. 5 mL Weigh sample into
Oils immediately flask and record

and 5 mL exact weight.
later

Ion equiv alent 10 -15 mL 12 min. 20 mL Digest will be clear
Exchange of 0.25 g with particles on
Resin dry resin bottom if metal

oxides are not
soluble in H
Add aqua regia or
suitable solv ent t o
dissolve particles.
If particles are
floating, start again
using 15 mL H
and longer char

time.
Soil 0.25 to 1.0 g 6 mL 4 min. 10 to 20 mL
Fuels/ 0.25 to 0.5 g 6 mL 4 min. 20 mL Heat the diluted

Lubricants digest for 15

minutes and filter .

Temperature of

heater may need to

be lowered slightly

if foaming or

burning occur.

2SO4

2SO4

.

SAFETY CONSIDERATIONS

Digesdahl Digestio n A pparatus

For safe Digesdahl operation:

•Sample size-Never exceed 0.5 grams of sample (dry weight)

•Oils and organic liquids should be considered as solids when
determining sample size.

•Acid type- Only use acid specified in Hach step-by-step procedures.

•Acid volume- Never use less than 3 mL.

•Always follow the order of steps indicated.

1-44

•Always wear safety glasses.

•Always perform digestion behind a safety shield or in a closed fume hood.

•If the sample goes to dryness, remove immediately and cool. Repeat
procedure with smaller sample volume or more acid.

The following additional specific safety precautions are appropriate
when using hydrogen peroxide in the Digesdahl digestion applications:

Do not mix hydrogen peroxide with any chemical reagents except as
specified in the instructions.

Do not add hydrogen peroxide directly to the column on the digestion
flask. Always add hydrogen peroxide in a slow and controlled manner;
use the capillary funnel.

Hydrogen peroxide s ho uld be added to the organic mater ials in t he f la sk
only when sulfuric acid is present.

Do not add alcohol, acetone or other organic solvents to the digestion
flask before or after digestion.

During digestion, use the heat setting and digestion time specified in the
instructions.

When digesting a new substance for the first time, begin with a smaller
size and work up to the optimum quantity for digestion.

The digestion flask and attached fr actionating colum n mu st b e vented at
all times.

During operation, the Digesdahl heating element and associated
glassware become very hot. Handle this glassware with the provided
finger cots protectin g the thumb and index finger. A hot di gestion flask
can scorch an unprotected surface. Use the cooling pad. If a flask
should break during a digestion, perform the following procedures to
avoid injury to personnel o r damage to e quipment:

1. Unplug the heater assembly and wait for the unit to cool.

2. Do not breathe any fumes that may be produced.

1-45

3. Hold the parts exposed to the digestion mixture under running water,

avoiding getti ng water or the digestion mixture int o the heater base.

If the aspirator fails during a digestion, immediately turn the heater off.
Do not breathe any fumes that may be expelle d from the manifold. After
the flask has cooled and the fumes subsided, clean or replace the
aspirator.

If the flask boils dry during the digestion, unplug the heater assembly
and allow the flask to cool. Remove the flask and discard the contents.
Repeat the digestion using less sample or more acid. If hydrogen
peroxide was added to the flask before it went dry, wait until the flask
cools completely. Add water to the flask before handling.

Chemicals

Concentrated sulfuric acid and hydrogen peroxide used in the digestion
process should be handled correctly and with caution. Sulfuric acid is a
strong acid and can cause burns if splashed on the skin and permanent
damage if eye contact occurs. Hydrogen peroxide (30% or 50%) is a
powerful oxidant and should never be stored near flammable materials.
Like sulfuric acid, it can cause burns and eye damage. In case of eye or
skin contact with either chemical, flush eyes and/or skin with water for
15 minute s. Remove contaminated c lothing. Call a physici an.

Both sulfuric acid and hydrogen peroxide are highly corrosive and
should be cleaned up with water if spilled on instruments or a counter
top. Read and observe all warnings on the reagent labels and Material
Safety Data Sheets (MSDS).

Proper handling and storage proce dures involving hydrogen peroxi de
should always address two major characteristics of the product: first, it is
a strong ox idizing age nt (corrosive), and second, it can decompose,
releasing heat and oxygen. The chemical nature of hydrogen peroxide
makes it an irritant to the skin, to mucus membranes and particularly to
the eyes. It will cause chemical bu rns at industrial concentrations and
may cause spontaneous combustion upon immediate or prolonged
contact with combustibles.

Hydrogen peroxide decomposes to form water and oxygen. The natural
decomposition rate of the normal industrial grade product is very low,
but it will accelerate when contaminated by materials such as dust,

1-46

metallic ions, or alkali. Accelerated decomposition from contamination
will result in the significant production of oxygen and liberation of heat.
These products will support combustion and will cause pressure bursts
in confined spaces. Commercial grades of hydrogen peroxide contain
small quantities of additives (termed "stabilizers'') to prevent accelerated
decomposition from occurring during normal product usage.

Please observe the following precautions for handling and storage of
hydrogen peroxide:

Do store in a cool place away from direct sunlight.

Do store in the original containers with closures as supplied and keep

closed when no t in use. (B e sure the c ontainers are vente d. Hach h ydrogen
peroxide bottles are shipp ed with a spe cial permeab le c ap liner.)

Do wear gloves and safety glasses when handling the material.

Do use silicon carbide boiling chips when digesting liquid samples.

Do wash contaminated skin and body quickly with plenty of water.

Remove cont aminated cloth ing an d w a sh well before using aga in. Wash
regularly.

Do wash eyes with plenty of water if contaminated and do get medical
advice quickly.

Do get medical advice without delay if the material is ingested.

Do flush all spillage with large amounts of water.

Do not store near heat sources or in contact with combustible or organic

materials.

Do not allow materials to be stored or trapped in confined spaces.

Do not inhale vapors or ingest the materials.

Do not allow contact with eyes or body.

Do not allow contact with decomposition catalysts (metals, dust, alkali, etc.) .

1-47

Do not use unapproved materials (brass, copper, carbon steel, rubber,

etc.) for transfer or storage systems.

Caps on the reagent bottles are made with a special porous liner that
allows venting of gas. The venting cap always must be used on the
bottle of hydrogen peroxide. As a precaution, the reagent bottles are
shipped in a plastic bag. If ther e is e vidence of leakage during s hipment,
wear gloves when removing the bottle from the bag and rinse the bottle
with water when removed from the bag. Rinse the bag before disposal.

APPLICATION-SPECIFIC MANUALS

Operating procedures for the Digesdahl Digestion Apparatus vary
according to the type a nd for m of the sample and h av e been pub lished in
a series of procedure manuals dedicated to specific applications. They
are available on request and provide the analyst with step-by step
instructions for sample digestion and subsequent analysis of specific
parameters. Specific setup and operating information is given in the
Digesdahl Digestion Apparatus instruction manual, included with each
Digesdahl. Application-specific manuals available include:

Literature Code Title

3120 Systems for Food, Feed and Beverage Analysis
3201 Fluid Fertilizer Analysis Manual
8353 Water Analysis Handbook

To receive a free copy of these manuals, contact Hach Customer
Services and request by literature code number.

DISTILLATION

Distillation is an effective way of separating chemical components for
analysis. The Hach Distillation Apparatus (see Figure 14) is adapted
easily for a variety of test needs. Sample distillations are easy and safe to
perform. It is suitable for water and wastewater requiring sample
distillation pretreatment. Applications for the General Purpose
Apparatus include: fluoride, albuminoid nitrogen, ammonia nitrogen,
phenols, selenium and volatile acids. Arsenic and cyanide require
specialty glassware sets in addition to the General Purpose Set. These
sets are the Arsenic Distillation Apparatus and the Cyanide Distillation
Apparatus. All connecting glassware is manufactured with threaded
connectors for ease and s afety. The General Purpose Heater and Sup port
Apparatus provide efficient heating and anchoring of the glassware.

1-48

Figure 14 General Purpose Distillation Apparatus

SAMPLING AND STORAGE

Correct sampling and storage are critical to the accuracy of each test.
For greatest accuracy minimize contamination from the sampling
device, remove residues of previous sampl es from samp le co ntai ner an d
preserve the sample properly, if necessary.

Taking Water Samples

Collect samples for analysis carefully to make sure the most
representative sample possible is obtained. In general, they should be

with Heater and Support Apparatus

1-49

taken near the center of the vessel or duct and below the surface. Use
only clean containers (bottles, beakers) for collecting samples. Rinse
the container several times first with the water to be sampled.

Take samples as closely as possible to the source of the supply to
minimize the effects of a distrib u tion system. Allo w the w ater to ru n for
sufficient time to flush the system, and the sample container should be
filled 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 difficult to obtain a truly representative sample when collecting
surface water samples. Best results are obtained by running a series of
tests with samples taken from several locations and depths at different
times. Results then can be used to establish patterns applicable to that
particular body of water.

Generally , as little time as possible should elapse between collecting the
sample and making the analysis.

Depending on the nature of the test, special precautions in handling the
sample also may be necessary to prevent natural interferences such as
organic growth or loss or gain of di ssolved gases. Sample preservatives
and storage techniques are described in each procedure for sample held
for later testing.

Acid Washing Bottles

A procedure may suggest acid-washing the sample bottles to minimize
the effect of interferences. This is accomplished by using a detergent to
clean the glassware or plastic-ware, rinsing with tap water, rinsing with a
1:1 Hydrochlor ic Acid Solut ion or 1: 1 Nitric Acid So lution, rinsin g with
deionized water . This may r equire successi v e rinses, up to 12 -15 may be
necessary if chromium is being determined. Air dry. The nitric acid
rinse also is important if lead is being determined.

Chromic acid or chromium-free substitutes may be used to remove
organic deposits from glass containers, but rinse containers thoroughly
with water to remove traces of chromium.

Glassware for phosphate determinations should be washed with
phosphate-free detergents and acid-washed with 1:1 HC1. This

1-50

glassware must be rinsed thoroughly with distilled water. For ammonia
and Kjeldahl nitrogen, the glassware must be rinsed with ammonia-free
water.

Storage and Preservation

The most cost-ef fecti v e sample con tainers are made of polypropylene or
polyethylene. The best and most expensive containers are made of
quartz or TFE (tetrafluoro ethy l ene, Teflon). Avoid soft glass containers
for metals in the microgram-per-liter range. Store samples for silver
determination in light-absorbing containers.

A v o id introducing contaminating metals from containers, distilled water
or membrane filters. Thoroughly clean sample containers as described
under Acid Washing Bottles.

Preservation techniques retard the chemical and biological changes
continuing after sample is taken. These changes may change the amo unt
of a chemical species available for analysis. As a general rule, it is best
to analyze the samples as soon as possible after collection. This is
especially true when the concentration is expected to be low. Analyzing
immediately reduces the potential for error and minimizes labor.

Preservation methods are limited generally to pH control, chemical
addition, refrigeration and fr eezing. Th e reco mmen ded pres ervation for
various constituents is given in Table 9. Other information provided in
the table is the suggested type of container and the maximum
recommended holding times for properly preserved samples.

Aluminum, cadmium, chromium, cobalt, copper, iron, lead, nickel,
phosphorus, potassium, silver and zinc samples can be preserved for at
least 24 hours by the addition of one Nitric Acid Solution Powder Pillow
1:1 (Cat. No. 2540-98) per liter of sample. Check the pH with pH
indicato r 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.

1-51

Table 9. Required Containers, Preservation Techniques and

Holding Times

1

Maximum

Parameter No./Name Container

2

Preservation

3,4

Holding Time

Table 1A-Bacterial Tests:

1-4. Colif orm, fecal P G Cool, 4°C, 0.00 8% 6 hours.

6

and total Na

2S2O3

5. Fecal streptococci P, G do do .

Table 1B-Inorganic Tests:

1. Acidity P, G Cool, 4°C 14 days.

2. Alkalinity P, G do do.

4. Ammonia P, G Cool, 4 °C, H

28 days.

2SO4

to pH< 2

9. Biochemical oxygen P, G Cool, 4 °C 48 hours.
demand

11. Bromide P, G None required 28 days .

14. Biochemical oxygen P, G Cool, 4 °C 48 hours.

demand, carbonaceou s

5

15. Chemical oxygen P, G Cool, 4 °C, H2SO4 28 days.

demand to pH< 2

16. Chloride P, G None required do .

17. Chlorine, total residual P, G do Analyz e

immediately.

21. Color P, G Cool, 4 °C 48 hours.
24-24. Cyanide, total and P, G Cool, 4 °C, NaOH 14 days

amenable to chlorination to pH >12,

0.6g ascorbic acid

6

25. Fluoride P None required 28 days .

27. Hardness P, G HNO

to pH< 2, 6 months.

3

to pH< 2

H

2SO4

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

31,43. Kjeldahl a nd P, G Cool, 4 °C, H

28 days.

2SO4

organic nitroge n to pH < 2

Metals:

8

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

7

.

1-52

Table 9 Required Containers, Preservation Techniques and

Holding Times

1

(continued)

Maximum

Parameter No./Name Container

2

Preservation

3,4

Holding Time

Metals (continued ):

35. Mercury P, G HNO

to pH < 2 28 days.

3

3, 5-8, 10, 12, 13, 19, 20 , P, G do 6 months.
22, 26, 29, 30, 32 -34, 36,
37, 45, 47, 51, 52 , 58-60,
62, 63, 70-72, 74, 75.

Metals, except chromium
VI and mercury.

38. Nitrate P, G Cool, 4 °C 48 hours.

39. Nitrate-nitrite

5

P, G Cool, 4 °C, H2SO4 28 days.

to pH < 2

40. Nitrite P, G Cool, 4 °C 48 hours.

41. Oil and grease G Cool, 4 °C, H

2SO4

28 days.

to pH < 2

42. Organic carbon P, G Cool, 4 °C, HCl or do.

to pH < 2

H

2SO4

5

44. Orthophosphate P, G Filter immediately, 48 hours.

Cool, 4 °C

46. Oxygen, G Bottle None required Analyze

Dissolv ed Prob e and top immediately.

47. Winkler do Fix on site an d 8 hours.

store in dark

48. Phenols G only Cool, 4 °C, H2SO4 28 days.

to pH < 2

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

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

28 days.

2SO4

to pH < 2

53. Residue, total P, G Cool, 4 °C 7 days.

54. Residue, Filterable P, G do 7 days.

55. Residue,

Nonfilterable (TSS) P, G do 7 da y s .

56. Residue, Settleable P, G do 48 hour s .

57. Residue, volatile P, G do 7 days.

1-53

Table 9 Required Containers, Preservation Techniques and

Holding Times

1

(continued)

Maximum

Parameter No./Name Container

2

Preservation

3,4

Holding Time

Metals (continued ):

61. Silica P do 28 days.

64. Specific conductance P, G do do.

65. Sulfate P, G do do.

66. Sulfide P, G Cool, 4 °C add 7 days.

zinc acetate plus
sodium hydroxide
to pH >9.

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. T urb id ity P, G Cool, 4 °C 48 hours .

5

1

This table was taken from T able II published in the

Part 136. 3, pa ge s 3 08 -30 9.

2

Polyethylene (P) or gl a ss (G ).

3

Sample preservation should be performed immediately upon sample collection. For composite
chemical samples each aliquot should be preserved by maintaining at 4 °C until compositing and
sample splitting is completed.

4

When any s am ple is to be ship pe d by common carrier or sent th ro ug h Uni t ed Sta te s Mail s, it
must comply with the Department of Transportation Hazardous Material Regulations (49 CFR
Part 172) . The pe rson of fering such material f o r transportation is responsi ble for ensuring su ch
compliance. For the preservation requirements of T a b le II, the Office of Hazardous Materials,
Materials Transportation Bureau, Department of Transportation has determined that Hazardous
Materials Regulations do not apply to the following materials: Hydrochloric acid (HCl) in water
solution s at c on cent r a ti ons of 0. 04 % b y wei g ht or le s s ( pH abo ut 1. 9 6 or gr eat er ); Nit ric aci d

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

(HNO

3

Sulfuric acid (H

1.15 or greater); and Sodium hydroxide (NaOH) in water solutions at concentrations of 0.080% by
weight or le ss (p H a bo ut 12 .3 0 or l es s).

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 permittee, or monitoring laboratory, has data on file to
show th at the s pec if i c type s o f s am ple s un de r s t ud y ar e st able for the longer ti me, 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 permittee, or monitoring laboratory, is
obliged 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.

6

Should only be used in th e pr ese nc e of re s idua l ch lori ne.

7

Maximum holding time is 24 hours when sulfide is present. Optionally all samples may be
tested wit h lead acet ate pape r bef ore pH adju stmen ts in order to determin e if sulfid e is pres ent. If
sulfide i s pr ese nt , it ca n b e re mo ved by the addition of ca dmiu m ni tr a te po w der unt i l a ne ga ti ve
spot test is obtained. The sample is filtered and then NaOH is added to a pH of 12.

8

Samples should be filtered immediately on-site before adding preservative for dissolved metals.

) in water solutions at concentrations of 0.35% by weight or less (about pH

2SO4

Federal Register

, October 1, 1991, 40 CFR,

1-54

Volume Additions, Correction For

When significant amounts of preservative are used, a volume correction
should be made. This will account for the acid added to preserve the
sample and the base used to adjust the pH to the rang e of the procedure.
This correction is made as follows:

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

2. Divide the total volume by the initial volume.

3. Multiply the test result by this factor.

An example:

A one-liter sample was taken and preserved with 2 mL of nitric acid. It
was neutralized with 5 mL of sodium hydroxide, 6 N. The result of the
analysis procedure was 10.00 mg/L. What is the volume correction
factor and correct result?

1.

Total volume = 1000 mL + 2 mL + 5 mL = 1007.

2.

1007
1000

10.00 mg/L x 1.007 = 10.07 mg/L = correct result

3.

= 1.007 = volume correction factor

The addition of a Sodium Carbonate Anhydrous Power Pillow does not
need to be corrected for.

1-55

1-56

SECTION II Procedures

2-a

2-b

DR/700 MODULE SELECTION GUIDE

Parameters and Ranges (alphabetical)

Modul e Nu m b e r Rea gen t

Description Range (Cat. No.) Package

Aluminum, Aluminon Method. . . . . . . . . . . . . . 0-1.0 mg/L . . . . 52.01 (46252-00). . . . 22420-00

Aluminum, Eriochrome Cyanine R Method. . . 0-0.25 mg/L . . . 52.01 (46252-00)

Arsenic*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-0.2 mg/L . . . . 52.01 (46252-00)

Barium. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-300 mg/L. . . . 45.01 (46245-00). . . . 12064-66

Benzotriazole . . . . . . . . . . . . . . . . . . . . . . . . . . 0-15 mg/L . . . . . 42.01 (46242-00). . . . 21412-66

Boron. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-15 mg/L. . . . . 61.01 (46261-00)

Bromine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-4 mg/L . . . . . . 52.01 (46252-00). . . . 21056-69

Cadmium, Anion Exchange . . . . . . . . . . . . . . . 0-100 µg/L . . . . 45.01

Cadmium, Dithizone. . . . . . . . . . . . . . . . . . . . . 0-70 µg/L . . . . . 52.01 (46252-00). . . . 22422-00

Chloride. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-20 mg/L . . . . . 45.01 (46245-00). . . . 23198-00

Chlorine, Free* . . . . . . . . . . . . . . . . . . . . . . . . . 0-3.5 mg/L . . . . 52.01 (46252-00). . . . 21055-69

Chlorine, Total* . . . . . . . . . . . . . . . . . . . . . . . . . 0-3.5 mg/L . . . . 52.01 (46252-00). . . . 21056-69

Chromium, Hexavalent* . . . . . . . . . . . . . . . . . . 0-1.000 mg/L . . 55.01 (46255-00). . . . 25050-25

Chromium, Total . . . . . . . . . . . . . . . . . . . . . . . . 0-0.700 mg/L . . 55.01 (46255-00). . . . 22425-00

Cobalt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-1.2 mg/L . . . . 61.01 (46261-00). . . . 22426-00

Color, Apparent and True . . . . . . . . . . . . . . . . . 0-500 Units. . . . 45.01 (46245-00)

Copper, Autocatalytic . . . . . . . . . . . . . . . . . . . . 0-3 g/L. . . . . . . . 81.01 (46281-00). . . . . 1042-66

Copper, Bicinchoninate*. . . . . . . . . . . . . . . . . . 0-3 mg/L. . . . . . 55.01 (46255-00). . . . 21058-69

Copper, P orphyrin. . . . . . . . . . . . . . . . . . . . . . . 0-200 µg/L . . . . 42.01 (46242-00). . . . 22427-00

Cyanide* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-0.2 mg/L . . . . 61.01 (46261-00)

Cyanuric Acid . . . . . . . . . . . . . . . . . . . . . . . . . . 0-65 mg/L. . . . . 50.01 (46250-00)

DEHA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-300 µg/L . . . . 55.01 (46255-00)

Fluoride, SPADNS*. . . . . . . . . . . . . . . . . . . . . . 0-2 mg/L. . . . . . 57.01 (46257-00). . . . 25060-25

Formaldehyde. . . . . . . . . . . . . . . . . . . . . . . . . . 0-625 µg/L . . . . 61.01 (46261-00). . . . 22577-00

Hardness, Calcium as CaCO
Hardness, Magnesium as CaCO

Hydrazine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-400 µg/L . . . . 45.01 (46245-00). . . . . 1790-37

Iodine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-6 mg/L. . . . . . 52.01 (46252-00). . . . 21056-69

Iron, Ferrous . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-5.00 mg/L . . . 50.01 (46250-00). . . . . 1037-69

Iron, FerroZine Method. . . . . . . . . . . . . . . . . . . 0-0.9 mg/L . . . . 55.01 (46255-00). . . . . 2301-66

Iron, Total, FerroVer Method. . . . . . . . . . . . . . . 0-5.00 mg/L . . . 50.01 (46250-00). . . . 21057-69

Iron, Total, TPTZ Method . . . . . . . . . . . . . . . . . 0-1 mg/L. . . . . . 57.01 (46257-00). . . . 22756-68

Lead, Anion Exchange. . . . . . . . . . . . . . . . . . . 0-120 µg/L . . . . 48.01

Lead, Dithizone* . . . . . . . . . . . . . . . . . . . . . . . . 0-140 µg/L . . . . 52.01 (46252-00). . . . 22431-00

Lead, LeadTrak. . . . . . . . . . . . . . . . . . . . . . . . . 0-150 µg/L . . . . 48.01 (46248-00). . . . 23750-00

Manganese, High Range* . . . . . . . . . . . . . . . . 0-20.0 mg/L . . . 52.01 (46252-00)

Manganese, Low Range . . . . . . . . . . . . . . . . . 0-0.800 mg/L . . 55.01 (46255-00). . . . 22433-00

Molybdenum, Molybdate, High Range . . . . . . 0-50 mg/L. . . . . 42.01 (46242-00). . . . 22434-00

Molybdenum, Molybdate, Low Range . . . . . . . 0-3.00 mg/L . . . 61.01

Nickel, Autocatalytic . . . . . . . . . . . . . . . . . . . . . 0-9 g/L. . . . . . . . 57.01 (46257-00). . . . 14321-98

Nickel, Heptoxime* . . . . . . . . . . . . . . . . . . . . . . 0-1.5 mg/L . . . . 42.01 (46242-00). . . . 22435-00

Nickel, PAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-0.6 mg/L . . . . 55.01 (46255-00). . . . 22426-00

Nitrate, High Range . . . . . . . . . . . . . . . . . . . . . 0-30 mg/L . . . . . 50.01 (46250-00). . . . 21061-69

Nitrate, High Range AccuVac. . . . . . . . . . . . . . 0-30 mg/L . . . . . 50.01 (46250-00). . . . 25110-25

Nitrate, Low Range. . . . . . . . . . . . . . . . . . . . . . 0-0.5 mg/L . . . . 50.01 (46250-00)

Nitrite, High Range . . . . . . . . . . . . . . . . . . . . . . 0-150 mg/L. . . . 57.01 (46257-00). . . . 21075-69

Nitrite, Low range* . . . . . . . . . . . . . . . . . . . . . . 0-0.2 mg/L . . . . 50.01 (46250-00). . . . 21071-69

Nitrogen, Ammonia, Nessler Method*. . . . . . . 0-3.0 mg/L . . . . 42.01 (46242-00)

Nitrogen, Ammonia, Monochloramine and
Free Ammonia 0-1.0 mg/L 61.01 46261-00 26184-00

. . . . . . . . . . . . . 0-2.7 mg/L . . . . 52.01 (46252-00). . . . 23199-00

3

. . . . . . . . . . 0-2 mg/L . . . . . . 52.01 (46252-00). . . . 23199-00

3

2-1

Modul e Nu m b e r Rea gen t

Description Range (Cat. No.) Package

Nitrogen, Ammonia, Salicylate Method . . . . . . 0-0-1.00 mg/L. . 61.01 (46261-00). . . . 22437-00

Oxygen, Dissolved, High Range . . . . . . . . . . . 0-10 mg/L. . . . . 52.01 (46252-00). . . . 25150-25

Oxygen, Dissolved, Low Range. . . . . . . . . . . . 0-800 µg/L . . . . 61.01 (46261-00). . . . 25010-25

Oxygen, Dissolved, Super High Range. . . . . . 0-40 mg/L. . . . . 69.01 (46269-00). . . . 25150-25

Oxygen Demand, Chemical, Reactor

Digestion Method, H.R. & S.H.R.* . . . . . . . 0-1500 &

0-15,000 mg/L. . 61.01 (46261-00)
Oxygen Demand, Chemical, Reactor

Digestion Method, Low Range* . . . . . . . . . 0-150 mg/L. . . . 42.01 (46242-00)

Ozone, High Range AccuVac. . . . . . . . . . . . . . 0-1.50 mg/L . . . 61.01 (46261-00). . . . 25180-25

Ozone, Low Range AccuV ac. . . . . . . . . . . . . . 0-0.25 mg/L . . . 61.01 (46261-00). . . . 25160-25

Ozone, Medium Range AccuVac. . . . . . . . . . . 0-0.75 mg/L . . . 61.01 (46261-00). . . . 25170-25

Palladium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-250 mg/L . . . . 42.01 (46242-00). . . . 23123-00

Phenols* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-0.2 mg/L . . . . 45.01 (46245-00). . . . 22439-00

Phosphonates. . . . . . . . . . . . . . . . . . . . . . . . . . 0-125 mg/L. . . . 81.01 (46281-00). . . . 22440-00

Phosphorus, Acid Hydrolyzable,

Test ’N Tube™ . . . . . . . . . . . . . . . . . . . . . . . 0-5.00 mg/L . . . 81.01 (46281-00)

Phosphorus, Reactive, Amino Acid . . . . . . . . . 0-20 mg/L. . . . . 52.01 (46252-00). . . . 22441-00

Phosphorus, Reactive, Molybdovanadate. . . . 0-45.0 mg/L . . . 42.01 (46242-00). . . . 20760-37

Phosphorus, Reactive, PhosVer 3* . . . . . . . . . 0-2.50 mg/L . . . 81.01 (46281-00). . . . 21060-69

Phosphorus, Reactive, Test ’N Tube™ . . . . . . 0-5.00 mg/L . . . 81.01 (46281-00)

Phosphorus, Total, Test ’N T ube™. . . . . . . . . . 0-5.00 mg/L . . . 81.01 (46281-00)

Platinum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-10 mg/L . . . . . 50.01 (46250-00)

Polyacrylic Acid . . . . . . . . . . . . . . . . . . . . . . . . 0-20mg/L . . . . . 50.01 (46250-00). . . . 22252-00

Potassium, Tetraphenylborate Method . . . . . . 0-8 mg/L. . . . . . 45.01 (46245-00)

Quaternary Ammonium Compounds. . . . . . . . 0-5.0 mg/L . . . . 57.01 (46257-00)

Residue, Nonfilterable . . . . . . . . . . . . . . . . . . . 0-750 mg/L. . . . 81.01 (46281-00)

Rhodium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-15 g/gal . . . . . 42.01 (46242-00)

Silica, High Range . . . . . . . . . . . . . . . . . . . . . . 0-40 mg/L. . . . . 42.01 (46242-00)

Silica, Low Range. . . . . . . . . . . . . . . . . . . . . . . 0-3 mg/L . . . . . . 81.01 (46281-00)

Silver, Colorimetric Method . . . . . . . . . . . . . . . 0-0.6 mg/L . . . . 57.01 (46257-00). . . . 22966-00

Sodium Chromate. . . . . . . . . . . . . . . . . . . . . . . 0-1000 mg/L. . . 45.01 (46245-00). . . . . 2127-99

Sulfate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-100 mg/L. . . . 45.01 (46245-00). . . . 21067-69

Sulfide* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-1 mg/L . . . . . . 61.01 (46261-00). . . . 22445-00

Surfactants, Anionic (as LAS) . . . . . . . . . . . . . 0-0.2 mg/L . . . . 61.01 (46261-00)

Tannin and Lignin . . . . . . . . . . . . . . . . . . . . . . . 0-9.00 mg/L . . . 69.01 (46269-00). . . . 22446-00

Tolyltriazole . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-15 mg/L. . . . . 42.01 (46242-00). . . . 21412-66

V olatile Acids (as HOA C) . . . . . . . . . . . . . . . . . 0-2500 mg/L. . . 50.01 (46255-00). . . . 22447-00

Zinc, Zincon Method* . . . . . . . . . . . . . . . . . . . . 0-3.00 mg/L . . . 61.01 (46261-00)

*USEPA Approved procedure

2-2

420-nm Filter Module (42.01) Cat. No. 46000-10

Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Range

Benzotriazole, Tolytriazole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 mg/L

Copper, P orphyrin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200 ug/L

Molybdenum, High Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 mg/L

Nickel, Heptoxime* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.5 mg/L

Nitrogen, Ammonia Nessler* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.0 mg/L

Oxygen Demand, Chemical, L.R* . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 mg/L

Palladium. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 mg/L

Phosphorus, Acid Hydrolyzable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NA

Phosphorus, Molybdovanadate . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45.0 mg/L

Phosphorus, Total* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NA

Rhodium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 g/gal

Silica, High Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 mg/L

450-nm Filter Module (45.01) Cat. No. 46000-11

Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Range

Barium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 mg/L

Cadmium, Anion Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100 ug/L

Chloride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mg/L

Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 Units

Hydrazine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-400 µg/L

Oil in Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 700 mg/L

Phenols* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.2 mg/L

Potassium (user calibration) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 mg/L

Sodium Chromate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 mg/L

Sulfate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 mg/L

480-nm Filter Module (48.01) Cat. No. 46000-12

Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Range

Lead, Anion Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120 ug/L

Lead, LeadTrak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150 ug/L

500-nm Filter Module (50.01) Cat. No. 46000-13

Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Range

Cyanuric Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 mg/L

Iron, Ferrous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.00 mg/L

Iron, Total, FerroVer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.00 mg/L

Nitrogen, Nitrate, High Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 mg/L

Nitrogen, Nitrate, H.R. AccuVac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 mg/L

Nitrogen, Nitrite, Low Range* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.2 mg/L

Platinum (user calibration) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mg/L

Poly acrylic Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mg/L

V oliti le Acids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2500 mg/L

2-3

525-nm Filter Module (52.01) Cat. No. 46000-14

Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Range

Aluminum, Aluminon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.0 mg/L

Aluminum, Erichrome Cyanine R . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.25 mg/L

Arsenic (user calibration)*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.2 mg/L

Bromine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 mg/L

Cadmium, Dithizone* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70 ug/L

Chlorine, Free . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . *3.5 mg/L

Chlorine, Total* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.5 mg/L

Hardness, Calcium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.7 mg/L

Hardness, Magnesium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.0 mg/L

Iodine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 mg/L

Lead, Dithizone* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .140 µg/L

Manganese, High Range*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20.0 mg/L

Oxygen, Dissolved, HRDO. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mg/L

Phosphorus, acid hydrolyzable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NA

Phosphorus, Amino Acid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mg/L

Phosphorus, total*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NA

550-nm Filter Module (55.01) Cat. No. 46000-15

Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Range

Chromium, Hexavalent* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.000 mg/L

Chromium, Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.700 mg/L

Copper, Bicinchoninate* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 mg/L

DEHA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300 ug/L

Iron, FerroZine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.9 mg/L

Manganese, Low Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.800 mg/L

Nickel, PAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.7 mg/L

575-nm Filter Module (57.01) Cat. No. 46000-16

Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Range

Fluoride* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 mg/L

Iron, Total, TPTZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 mg/L

Nickel, Au tocatalytic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 g/L

Nitrogen, Nitrite, High Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 mg/L

Quaternary Ammonium Compounds . . . . . . . . . . . . . . . . . . . . . . . . . .5.0 mg/L

Silver , Colorimetric. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.6 mg/L

610-nm Filter Module (61.01) Cat. No. 46000-17

Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Range

Boron. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 mg/L

Cobalt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2 mg/L

Cyanide* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.2 mg/L

Formaldehyde . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .625 ug/L

Molybdenum, Low Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.00 mg/L

Nitrogen, Ammonia, Salicylate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 mg/L

Nitrogen, Monochloramine and Free Ammonia . . . . . . . . . . . . . . . 0-1.00 mg/L

2-4

610-nm Filter Module (61.01) Cat. No. 46000-17 (continued)

Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Range

Oxygen Dissolved, LRDO AccuVac. . . . . . . . . . . . . . . . . . . . . . . . . . .800 ug/L

Oxygen Demand, Chemical,

High Range and High Range Plus . . . . . . . . . . . . . . . . 1500 & 15,000 mg/L

Ozone, Low Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.25 mg/L

Ozone, Medium Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.75 mg/L

Ozone, High Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.50 mg/L

Surfactants, Anionic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.2 mg/L

Sulfide*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 mg/L

Zinc, Zincon* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.00 mg/L

690-nm FIlter Module (69.01) Cat. No. 46000-18

Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Range

Oxygen, Dissolved, SHRDO. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 mg/L

Tannin and Lignin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9.00 mg/L

810-nm Filter Module (81.01) Cat. No. 46000-19

Parameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Range

Copper, Autocatalytic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 g/L

Phosphonates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 mg/L

Phosphorus, Acid Hydrolyzable . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-5.00 mg/L

Phosphorus, PhosoVer 3*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.50 mg/L

Phosphorus, Reactive, Test ’N Tube. . . . . . . . . . . . . . . . . . . . . . . . 0-5.00 mg/L

Phosphorus, Total*, Test ’N T ube . . . . . . . . . . . . . . . . . . . . . . . . . . 0-5.00 mg/L

Residue, Nonfilterable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750 mg/L

Silica, Low range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 mg/L

LR = Low Range SHR = Super High Range g/L = grams per liter
MR = Medium Range HR+ = High Range Plus g/gal = grams per gallon
HR = High Range mg/l (milligrams per liter) = ppm (parts per million)

*USEPA approved procedure

Key to Abbreviations

2-5

2-6

Module 42.01

420 nm

Hach warrants equipment it manufactures against defective materials or
workmanship for at least one year from the shippi ng date. Warranties do
not apply to limited-life electrical components such as batteries. Full
warranty information is located on the reverse side of Hach invoices.

A lamp intensity adjustment must be performed:

•Before first or initial use

•When new filter modules are installed

•On each filter module when the lamp is replaced
Refer to Lamp Intensity Adjustment in the instrument manual.

IMPORTANT NOTICE

Table of Contents for 420-nm parameters

Benzotriazole, Tolyltriazole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42-1

Copper, Porphyrin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42-9

Molybdenum, Molybdate, High Range. . . . . . . . . . . . . . . . . . . . . .42-17

Nickel, Heptoxime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42-23

Nitrogen Ammonia, Nessler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42-33

Oxygen Demand, Chemical, Low Range . . . . . . . . . . . . . . . . . . . . 42-41

Palladium. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42-51

Phosphorus, Acid Hydrolyzable (hydrolysis procedure) . . . . . . . .42-57

Phosphorus, Reactive, Molybdovanadate . . . . . . . . . . . . . . . . . . . . 42-61

Phosphorus, Total (digestion procedure). . . . . . . . . . . . . . . . . . . . . 42-69

Rhodium (user calibration) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42-75

Silica, High Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42-81

Method 8079

,

BENZOTRIAZOLE OR TOL YL TRIAZOLE

(0 to 15.0 mg/L Benzotriazole; 0 to 20.0 mg/L Tolyltriazole)

For cooling and boiler water
UV Photolysis Method*

1. Install module

42.01

in a DR/700.

Note: The most reliable
results are obtained
when samples are
analyzed as soon as
possible after
collection.

2. Press: I/O

The display will show

420 nm

and module

42.01

3. After 2 seconds,

the display will show
a program number,
the concentration
units and the zero
prompt. If necessary,
press the
key until the lower
display shows
program number

42.01.1

for benzotriazole or

42.10.1

for tolyltriazole.

UP ARRO W

*Adapted from Harp, D., Proceedings 45th International Water Confe rence,
October 1984

299

42-1

BENZOTRIAZOLE AND TOLYLTRIAZOLE, continued

4. Fill a square

mixing bottle with
25 mL of sample.

Note: For proof of
accuracy, use a 5.0 mg/L
benzotriazole stan dard
solution (preparation
given in Accuracy
Check) in place of the
sample.

Note: Sample
temperature should be

o

between 20 to 25

o

(68 to 70

Note: If sample contains
nitrite or borax (sodium
borate), adjust the p H to
between 4 to 6 with 1 N
Sulfuric Acid.

F).

C

5. Add the contents

of one Triazole
Reagent Powder
Pillow (the prepared
sample). Swirl to
dissolve completely.

Note: If sample contains
more than 500 mg/L
hardness (as CaCO3),

add 10 drops of
Rochelle Salt Solution.

6. Insert the

ultraviolet lamp into
the mixing bottle.

Note: UV safety gog gles
should be worn while
the lamp is on.

42-2

BENZOTRIAZOLE AND TOLYLTRIAZOLE, continued

5 minutes

7. Turn the UV lamp

on.

Note: A yellow color
will develop if triazole is
present.

8. Wait 5 minutes. 9. Turn the lamp off.

Remove lamp from
the bottle Swirl to
mix thoroughly.

Note: Low results will
occur if photolysis
(lamp on) take s place
for more or less than
five minutes.

Note: Avoid fingerprints
on the quartz surface of
the lamp. Rinse the
lamp and wipe with a
soft, clean tissue
between tests.

10. Fill a 10-mL cell

to the 10-mL line
with the prepared
sample.

11. Fill another

10-mL cell to the
10-mL line with
sample (t he blank).

42-3

12. Place the blank

in the cell holder.

BENZOTRIAZOLE AND TOLYLTRIAZOLE, continued

13. Press: ZERO

The display will
count down to 0.
Then the display will
show 0.00 mg/L and
the zero prompt will
turn off.

SAMPLING AND STORAGE

The most reliable results are obtained when samples are analyzed as
soon as possible after collection.

ACCURACY CHECK
Standard Addi ti on s Method

a) Use the TenSette Pipet to add 0.1, 0.2 and 0.3 mL of standard

solution, 500 mg/L benzotriazole, to three 25-mL samples. Perform the
test according to the above procedure.

Note: The test will not distinguish between benzotr iazole and tolyltriazole.

14. Place the

prepared sample in
the cell holder.

Note: In bright sunlight
it may be necessary to
close the cell
compartment cover.

15. Press: READ

The display will
count down to 0.
Then the display will
show the results in
mg/L benzotriazole
or tolyltriazole.

b) Each addition of 0.1 mL of standard solution should increase the
benzotriazole reading by 2 mg /L o v er the r eading of an unspik ed samp le.

c) If these increases are not obtained see Standard Additions (Section I)
for more information.

UV Lamp Check

T o verify the ultra violet lamp (normal life equals 5000 hours) is working
properly, perform the following test:

a) Prepare a 5.0 mg/L benzotriazole s tandard solution by pipetting

10.0 mL of benzotriazole standard solution, 500 mg/L benzotriazole,
into a 1-L volumetric flask. Dilute to volume.

42-4

BENZOTRIAZOLE AND TOLYLTRIAZOLE, continued

b) Analyze according to the above procedure. If the result is

significantly below 5.0 mg/L, replace the lamp.

STATISTICAL EVALUATION

A single operator repetitively tested samples of two laboratory prepared
solutions, using one DR/700, matched sample cells and two
representative lots of reagent. Testing 10.0 mg/L tolyltriazole
concentration solutions, the standard deviation was ±0.22 mg/L
tolyltriazole. Testing zero concentration samples, the limit of detection
was 0.17 mg/L tolyltriazole.

Testi ng 10.0 mg/L benzot riazole concentration solutions, the standard
deviation was ±0.11 mg/L benzotriazole. Testing zero concentration
samples, the limit of detection was 0.16 mg/L benzotriazole.

The limit of detection was calculated as three times the standard
deviation when testing zero concentration samples (adapted from

Analytical Chemistry, 1980, 52, 2242-2249).

INTERFERENCES

The following may interfere when present in concentrations exceeding
those listed below:
Acrylates (as methyl acrylate) 50 mg/L
Alum 400 mg/L
Borate (as sodium tetraborate) 4000 mg/L
Chlorine (as Cl
Chromium (as chromate) 12 mg/L
Copper 10 mg/L
Hardness 500 mg/L as CaCO

Iron 20 mg/L
Lignosulfonates 40 mg/L
Magnesium 300 mg/L as CaCO

Molybdenum (as molybdate) 200 mg/L
Nitrite 4000 mg/L
Phosphonates (AMP or HEDP) 100 mg/L
Sulfate 200 mg/L
Zinc 80 mg/L

)20 mg/L

2

3

3

Strong oxidizing or reducing agents present in the sample will interfere
directly.

42-5

BENZOTRIAZOLE AND TOLYLTRIAZOLE, continued

SUMMARY OF METHOD

Benzotriazole or tolyltriazole, used in many applications as corrosion
inhibitors for copper and copper alloys, are determined by a proprietary
catalytic ultraviolet (UV) photolysis procedure requiring less than 10
minutes to perform.

REQUIRED REAGENTS

Quantity
Description Per Test Unit Cat. No.

Triazole Reagent

Powder Pillows . . . . . . . . . . . . . . 1 pillow. . . . 50/pkg. . . . . .21412-66

REQUIRED APPARATUS

Bottles, square, mixing,

25-mL mark. . . . . . . . . . . . . . . . . 1 . . . . . . . . . each. . . . . . . .17042-00

Clippers, for opening

powder pillows. . . . . . . . . . . . 1 . . . . . . . . . each. . . . . . . . . .968-00

DR/700 Filter Module

Number 42.01. . . . . . . . . . . . . 1 . . . . . . . . . each. . . . . . . .46242-00

Stopwatch . . . . . . . . . . . . . . . . . . 1 . . . . . . . . . each. . . . . . . . 14645-00

UV Safety Goggles . . . . . . . . . . . 1 . . . . . . . . . each. . . . . . . . 21134-00

Select one based on available voltage:

Lamp, UV, with power supply,

115 Vac, 60 Hz . . . . . . . . . . . . . . . . . . . . . . . each. . . . . . . . 20828-00

Lamp, UV, with power supply,

230 Vac, 50 Hz . . . . . . . . . . . . . . . . . . . . . . . each. . . . . . . . 20828-02

OPTIONAL REAGENTS

Benzotriazole Standard Solution, 500 mg/L . . . . 100 mL. . . . . . 21413-42

Rochelle Salt So lu tion. . . . . . . . . . . . . . . . . . . . . . 29 mL* DB . . . 1725-33

Sulfuric Acid Standard Solution, 1.0 N . . . . . . . . .100 mL MDB. . 1270-32

OPTIONAL APPARATUS

Cap for 10- and 25-mL Sample Cells . . . . . . . . 12/pkg. . . . . . 24018-12

Flask, volumetric, 1000 mL . . . . . . . . . . . . . . . each . . . . . . . . 14574-53

Lamp, UV, (lamp only) . . . . . . . . . . . . . . . . . . . each. . . . . . . . 20823-00

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

Pipet Filler, safety bulb . . . . . . . . . . . . . . . . . . . each. . . . . . . . 14651-00

*Contact Hach for larger siz es.

42-6

BENZOTRIAZOLE AND TOLYLTRIAZOLE, continued

OPTIONAL APPARATUS (continued)

Description Unit Cat. No.

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

Pipet Tips, for 19700-01 Tensette Pipet . . . . . . 50/pkg. . . . . . 2 1856-96

Pipet, volumetric, Class B, 10 mL. . . . . . . . . . . each . . . . . . . . . 515-38

Sample Cell, 10-mL with screw cap . . . . . . . . . 6/pkg. . . . . . . 24276-06

Sample Cell, 25-mL with screw cap . . . . . . . . . 6/pkg. . . . . . . 24019-06

Single to dual UV lamp cord adapter . . . . . . . . each . . . . . . . 19485-00

Timer, interval, 1 second to ten hours . . . . . . . . each. . . . . . . 23480-00

For Technical Assistance, Prices and Ordering

In the U. S.A. - Call 800-227-4224 toll-free for more information.
Outside the U.S.A. - Contact the Hach offi ce or distributor serving you.

42-7

42-8

COPPER (0 to 250 µg/L)

For water, wastewat er and seawater
Porphyrin Metho d*

Method 8143

1. Install module

42.01

in a DR/700.

Note: If samples cannot
be analyzed
immediately, see
Sampling and Storage
following these steps.
Adjust the pH of stored
samples before analysis.

2. Press: I/O

The display will show

420 nm

and module number

42.01

Note: Total copper
determination needs a
prior digestion; use
either the Digesdahl or
vigorous digestion
(Section 1).

3. After 2 seconds,

the display will show
a program number,
the concentration
units and the zero
prompt. If necessary,
press the
key until the lower
display shows
program number

UP ARROW

42.02.1

*Adapted from Ishii an d Koh, Buseki Kagak u, 28, 473 (1979)

42-9

COPPER, continued

4. Fill two 25-mL

cells to the 25-mL
line with sample.

Note: Wash all
glassware with
deterg e n t. Rinse with
tap water. Rinse again
with Nitric Acid
Solution, 1:1. Rinse a
third time with copper­free, demineralized
water.

Note: For proof of
accuracy, use a 100 µg/L
copper st andar d solu tion
(preparation given in
Accuracy Check) in
place of the sample.

5. Add the contents

of one Copper
Masking Po wder
Pillow to one of the
sample cells (the
blank). Cap and
invert sev eral times to
mix.

Note: The other sample
cell is the prepared
sample.

6. Add the contents

of one Porphyrin 1
Reagent Powder
Pillow to each sample
cell. Cap and invert
several times to mix.

42-10

COPPER, continued

3 minutes

7. Add the contents

of one Porphyrin 2
Reagent Powder
Pillow to each sample
cell. Cap and invert
several times to mix.

Note: The yellow color
will turn blue
momentarily. If any
copper is pr e s ent, the
sample will return to
yellow.

8. Wait 3 minutes. 9. Place the blank in

the cell holder.

Note: Typical indoor
lighting permits the
DR/700 to operate with
the cell compartment
open. In bright
sunlight, it may be
necessary to close the
cell compartment cover .
Transfer 10 mL of the
blank and 10 mL of the
sample to a
10-mL sample cell and
proceed.

42-11

COPPER, continued

10. Press: ZERO

The display will count
down to 0. Then the
display will sho w 0
µg/L and the zero
prompt will turn of f.

11. Place the

prepared sample in
the cell holder.

Note: T ypical indoor
lighting permits th e
DR/700 to operate with
the cell compartme n t
open. In bright sunlight,
it may be necessary to
close the cell
compartment cover.
Tr ansfer 10 mL of the
blank and 10 mL of the
sample to 10-mL sample
cell and proceed.

Note: If standards or
samples with high levels
of metal ar e an alyz ed, a
slight metallic deposit
or yellow buildup may
appear on the sample
cell wall. Remove by
rinsing with nitric acid.

12. Press: READ

The display will
count down to 0.
Then the display will
show the results in
µg/L copper
(Cu Porphyrin).

Note: For most accurate
results, run the test
using copper-free
demineralized water.
Subtract the value
obtained in Step 12 fr om
all following tests.
Repeat for ea ch new lot
of reagents.

42-12

COPPER, continued

SAMPLING AND STORAGE

Collect samples in acid-washed plastic bottles. To preserve, adjust the
pH to 2 or less with nitric acid (about 5 mL per liter). Store preserved
samples up to six months at room temperature.

Before testing, adjust the pH of the sample to between 2 and 6. If the
sample is too acidic, adjust the pH with 5.0 N Sodium Hydroxide
Standard Solution. Correct test results for volume additions; see
Sampling and Storage, Volume Additions, (Section I) for more
information.

A CCURACY CHECK

Standard Additions Method
a) Using a TenSette Pipet, add 0.1 mL of Copper Standard Solution,

10.0 mg/L Cu, to two sample cells containing 25 mL of sample.

b) Repeat, using 0.2 mL and 0.3 mL additions of standard.

c) Analyze the samples as described above. The copper concentration

reading should increase by 40 µg/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

To assure the accuracy of the test, prepare a 100-µg/L copper standard:
a) Pipet 1.00 mL of copper standard solution, 10.0 mg/L Cu, into a
100-mL volumetric flask.

b) Dilute to volume with copper-free, reagent-grade water.

c) Use this standard in place of the sample in the procedure.

d) Prepare this solution daily.

STATISTICAL EVALUATION

A single operator repetitively tested samples of two laboratory prepared
solutions, using one DR/700, matched sample cells and two
representative lots of reagent. Testing 150 µg/L Cu concentration
solutions, the standard deviation was ±1.2 µg/L Cu.

42-13

COPPER, continued

Testing zero concentration samples, the limit of detection was 1.7 µg/L
Cu. The limit of detection was calculated as three times the standard
deviation when testing zero concentration samples (adapted from

Analytical Chemistry, 1980, 52, 2242-2249).

INTERFERENCES

The following may interfere when present in concentrations exceeding
those listed below:

Aluminum 60 mg/L
Cadmium 10 mg/L
Calcium 1,5000 mg/L
Chloride 90,000 mg/L
Chromium (Cr
Cobalt 100 mg/L
Fluoride 30,000 mg/L
Iron 6 mg/L
Lead 3 mg/L
Magnesium 10,000 mg/L
Manganese 140 mg/L
Mercury 3 mg/L
Molybdenum 11 mg/L
Nickel 60 mg/L
Potassium 60,000 mg/L
Sodium 90,000 mg/L
Zinc 9 mg/L

6+

) 110 mg/L

Chelating agents, such as EDTA, interfere at all levels unless either the
Digesdahl or vigorous digestion (Section I) is performed.

Highly buff ered samples or extreme sample pH may exceed the
buffering capacity of the reagents and require sample pretreatment: see
Interferences, pH (Section I)

SUMMARY OF METHOD

The porphyrin method is very sensitive to trace amounts of free copper.
The method is free from most interferences and does not require any
sample extraction or preconcentration. Interferences from other metals
are eliminated by the copper masking reagent. The porphyrin indicator
forms an intense, yellow-colored complex with any free copper present
in sample.

42-14

COPPER, continued

REQUIRED REAGENTS

Cat. No.

Copper Reagent Set (100 Tests) . . . . . . . . . . . . . . . . . . . . . . . 22427-00

Includes: (2) 21873-66, (4) 21874-66, (2) 21875-69

Quantity
Description Per Test Unit Cat. No.

Copper Masking Reagent

Powder Pillows . . . . . . . . . . . 1 pillow. . . . 100/pkg. . . . .21873-99

Porphyrin 1 Reagent

Powder Pillows . . . . . . . . . . . 2 pillows. . . 100/pkg. . . . . 21874-69

Porphyrin 2 Reagent

Powder Pillows . . . . . . . . . . . 2 pillows. . . 100/pkg. . . . 21875-69

REQUIRED APPARATUS

Clippers, for opening

powder pillows . . . . . . . . . . . 1 . . . . . . . . . each. . . . . . . . . . 968-00

DR/700 Filter Module

Number 42.01. . . . . . . . . . . . . 1 . . . . . . . . . each. . . . . . . .46242-00

OPTIONAL REAGENTS

Copper Standard Solution, 10 mg/L Cu . . . . . . 100 mL MDB . . 129-32

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

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

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

Sodium Hydroxide Standard Solution, 5 N . . . . 1 L . . . . . . . . . .2450-53

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

OPTIONAL APPARATUS

Beaker, 100 mL . . . . . . . . . . . . . . . . . . . . . . . . . each. . . . . . . . . . 500-42

Cap for 10- and 25-mL sample cells. . . . . . . . . 12/pkg. . . . . . 24018-12

Flask, volumetric, Class A, 50 mL . . . . . . . . . . each. . . . . . . . 14574-41

Flask, volumetric, Class A, 100 mL . . . . . . . . . each. . . . . . . . 14574-42

Hot Plate, 7" x 7", 120 Vac . . . . . . . . . . . . . . . . each. . . . . . . . 23441-00

Hot Plate, 7" x 7", 240 Vac . . . . . . . . . . . . . . . . each. . . . . . . . 23441-02

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

Pipet, Mohr, 5 mL . . . . . . . . . . . . . . . . . . . . . . . each. . . . . . . . 20934-37

Pipet, TenSette, 0.1 to 1.0 mL. . . . . . . . . . . . . . each. . . . . . . . 14515-35

Pipet, volumetric, Class A, 1 mL . . . . . . . . . . . each. . . . . . . . 14515-35

Pipet, volumetric, Class A, 50 mL . . . . . . . . . . each. . . . . . . . 14515-41

Pipet Filler, safety bulb . . . . . . . . . . . . . . . . . . . each. . . . . . . . 14651-00

Sample Cell, 10-mL with screw cap . . . . . . . . . 6/pkg. . . . . . . 24276-06

42-15

COPPER, continued

OPTIONAL APPARATUS (continued)

Description Unit Cat. No.

Sample Cell, 25-mL with screw cap . . . . . . . . . 6/pkg. . . . . . . 24019-06

Watch Glass. . . . . . . . . . . . . . . . . . . . . . . . . . . . each. . . . . . . . . . 578-70

For Technical Assistance, Prices and Ordering

In the U. S.A. - Call 800-227-4224 toll-free for more information
Outside the U.S.A. - Contact the Hach offi ce or distributor serving you.

42-16