EUTECH INSTRUMENTS EC-PB-03, EC-SCS-PB1-BT, EC-SCS-PB2-BT, EC-ISA-PB1-BT, EC-MIS-PP Instruction Manual

EUTECH INSTRUMENTS PTE LTD.

INSTRUCTION MANUAL

LEAD ION ELECTRODE

TABLE OF CONTENTS

GENERAL INSTRUCTIONS ..........................................................................................................1

Introduction..............................................................................................................................................2

Required Equipment.................................................................................................................................2

Required Solutions...................................................................................................................................2

GENERAL PREPARATION............................................................................................................3

Electrode Preparation...............................................................................................................................3

Electrode Slope Check (with pH/mV meter) ...........................................................................................3

Electrode Slope Check (with ion meter) ..................................................................................................3

MEASUREMENT..............................................................................................................................4

Measuring Hints.......................................................................................................................................4

Sample Requirements...............................................................................................................................4

Units of Measurement..............................................................................................................................5

MEASUREMENT PROCEDURE ...................................................................................................5

Direct Measurement.................................................................................................................................5

Direct Measurement of Lead (using a pH/mV meter)..............................................................................5

Direct Measurement of Lead (using an ion meter)...................................................................................7

Low Level Lead Determination (using a pH/mV meter) .........................................................................8

Low Level Lead Determination (using an ion meter)..............................................................................9

Titration..................................................................................................................................................10

Titration of Lead ....................................................................................................................................10

Titration of Sulfate.................................................................................................................................11

ELECTRODE CHARACTERISTICS...........................................................................................13

Reproducibility.......................................................................................................................................13

Interferences...........................................................................................................................................13

Precipitation and Complexation.............................................................................................................13

Temperature Influences..........................................................................................................................13

Electrode Response................................................................................................................................14

Limits of Detection.................................................................................................................................14

pH Effects...............................................................................................................................................15

Electrode Life.........................................................................................................................................15

Electrode Storage ...................................................................................................................................15

ELECTRODE THEORY................................................................................................................15

Electrode Operation ...............................................................................................................................15

TROUBLESHOOTING GUIDE....................................................................................................17

Meter......................................................................................................................................................17

Glass-ware/Plastic-ware.........................................................................................................................17

Electrodes...............................................................................................................................................17

Sample....................................................................................................................................................17

Technique...............................................................................................................................................18

TROUBLESHOOTING HINTS.....................................................................................................19

SPECIFICATIONS..........................................................................................................................21

ORDERING INFORMATION.......................................................................................................21

Instruction Manual Lead Electrode

1

GENERAL INSTRUCTIONS ............................................................Error! Bookmark not defined.

Introduction............................................................................................................Error! Bookmark not defined.

Required Equipment...............................................................................................Error! Bookmark not defined.

Required Solutions.................................................................................................Error! Bookmark not defined.

GENERAL PREPARATION.........................................................ERROR! BOOKMARK NOT DEFINED.

Electrode Preparation...................................................................................... ERROR! BOOKMARK NOT DEFINED.

Electrode Slope Check (with pH/mV meter)................................................... E

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Electrode Slope Check (with ion meter) .........................................................E

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MEASUREMENT..............................................................................................Error! Bookmark not defined.

Measuring Hints.............................................................................................. ERROR! BOOKMARK NOT DEFINED.

Sample Requirements...................................................................................... E

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Units of Measurement..................................................................................... E

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MEASUREMENT PROCEDURE .....................................................Error! Bookmark not defined.

Direct Measurement........................................................................................ ERROR! BOOKMARK NOT DEFINED.

Direct Measurement of Silver (using a pH/mV meter) ................................... E

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Direct Measurement of Silver (using an ion meter)........................................ E

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Direct Measurement of Sulfide (using a pH/mV meter) ................................. E

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Direct Measurement of Sulfide (using an ion meter)...................................... E

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Low Level Silver Determinations (using a pH/mV meter) ............................. E

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TITRATION......................................................................................... Error! Bookmark not defined.

Titration of Sulfide.......................................................................................... ERROR! BOOKMARK NOT DEFINED.

Titration of Silver............................................................................................ E

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Low Level Chloride Titration.......................................................................... E

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Indicator Titration ...........................................................................................E

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ELECTRODE CHARACTERISTICS............................................... Error! Bookmark not defined.

Reproducibility................................................................................................ ERROR! BOOKMARK NOT DEFINED.

Interference...................................................................................................... E

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Complexation.................................................................................................. E

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Temperature Influences...................................................................................E

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Electrode Response ......................................................................................... E

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Limits of Detection.......................................................................................... E

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pH Effects........................................................................................................ E

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Electrode Life..................................................................................................E

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Electrode Storage ............................................................................................ E

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ELECTRODE THEORY....................................................................Error! Bookmark not defined.

Electrode Operation......................................................................................... ERROR! BOOKMARK NOT DEFINED.

TROUBLESHOOTING GUIDE........................................................ Error! Bookmark not defined.

Meter ............................................................................................................... ERROR! BOOKMARK NOT DEFINED.

Glassware........................................................................................................ E

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Electrodes........................................................................................................ E

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Standards and Reagents................................................................................... E

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Sample.............................................................................................................E

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Technique........................................................................................................E

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TROUBLESHOOTING HINTS......................................ERROR! BOOKMARK NOT DEFINED.

SPECIFICATIONS.............................................................................. Error! Bookmark not defined.

ORDERING INFORMATION........................................ERROR! BOOKMARK NOT DEFINED.

EUTECH INSTRUMENTS PTE LTD.

LEAD ION ELECTRODE

INSTRUCTION MANUAL

GENERAL INSTRUCTIONS

Introduction

Eutech Instruments Lead Ion Electrode is used to measure lead or sulfate ions in aqueous solutions
quickly, simply, accurately, and economically.

Required Equipment

1. A pH/mV meter or an ion meter, either line operated or portable.

2. Semi-logarithmic 4-cycle graph paper for preparing calibration curves when using the
meter in the mV mode. Linear graph paper is recommended for low level measurements or
lead/sulfate titration.

3. A magnetic stirrer.

4. Eutech Lead Ion Combination Epoxy-body Electrode, Code no. EC-PB-03.

6. Lab-ware made of plastic, not glass, for all low level measurements.

7. Polishing Paper, Code no. EC-MIS-PP, to polish dirty or etched electrode membranes.

Required Solutions

1. Deionized or distilled water for solution and standard preparation.

2. Methanol-formaldehyde solution. To prepare this solution from your own laboratory stock,
add 3 drops of 37% formaldehyde to 1,000 ml of reagent-grade methanol. This solution is
used to decrease the solubility and retard oxidation of the membrane.

3. Eutech Ionic Strength Adjuster (ISA), 5M NaClO4, Code No. EC-ISA-PB1-BT. To
prepare this solution from your own laboratory stock, half fill a one liter volumetric flask
with distilled water and add 700 grams of reagent-grade NaClO4·H2O. Swirl the flask
gently to dissolve the solid. Fill the flask to the mark with distilled water, cap, and upend
several times to mix the solution. To each 100 ml of standard or sample, add 2 ml of ISA.
The background ionic strength of the resulting solution will be 0.1M.

4. Eutech Lead Perchlorate Standard, 0.1M Pb(ClO4)2, Code no. EC-SCS-PB1-BT. To
prepare this solution from your own laboratory stock, half fill a one liter volumetric flask
with distilled water and add 46.01 grams of reagent-grade lead perchlorate,

Instruction Manual Lead Electrode

3

Pb(ClO4)2·3H2O. Swirl the flask gently to dissolve the solid. Fill the flask to the mark with
distilled water, cap, and upend several times to thoroughly mix the solution.

5. Eutech Lead Perchlorate Standard, 1,000 ppm Pb(ClO4)2, Code no. EC-SCS-PB2-BT. To
prepare this solution from your own laboratory stock, half fill a one liter volumetric flask
with distilled water and add 2.30 grams of reagent-grade lead perchlorate,
Pb(ClO4)2·3H2O. Swirl the flask to dissolve the solid. Fill the flask to the mark with
distilled water, cap, and upend several times to thoroughly mix the solution.

GENERAL PREPARATION

Electrode Preparation

Remove the rubber caps covering the electrode tips and the rubber insert covering the filling hole of
the lead combination ion electrode or the reference electrode. Fill the reference electrode or the
combination electrode with the filling solution shipped with the electrode to a level just below the
fill hole. No preparation is required with a sealed reference electrode. Connect the electrodes to the
proper terminals as recommended by the meter manufacturer.

Electrode Slope Check (with pH/mV meter)

(Check electrodes each day)

1. To a 150 ml beaker, add 50 ml of methanol-formaldehyde solution and 50 ml of distilled
water. Add 2 ml of ISA. Place the beaker on a magnetic stirrer and begin stirring at a
constant rate. After assuring that the meter is in the millivolt mode, lower the electrode tips
into the solution.

2. Using a pipet, add 1 ml of 0.1M or 1,000 ppm lead standard to the beaker. When the
reading has stabilized, record the mV reading.

3. Using a pipet, add 10 ml the same lead standard used above to the beaker. When the
reading has stabilized, record the mV reading.

4. Determine the difference between the two readings. The electrode is operating correctly if
the millivolt potential has changed by 25±2, assuming the temperature is between 20

o

and

25

o

C. See the TROUBLESHOOTING sections if the potential change is not within this range.

Slope is defined as the change in potential observed when the concentration changes by a factor of

10.

Electrode Slope Check (with ion meter)

(Check electrodes each day)

1. Prepare standard lead solutions whose concentrations vary by tenfold. Use either the 0.1M
or 1,000 ppm lead standard. Use the serial dilution method for this preparation.

2. To a 150 ml beaker, add 50 ml of methanol-formaldehyde solution and 50 ml of the lower
value standard. Add 2 ml of ISA. Place the beaker on a magnetic stirrer and begin stirring
at a constant rate. Lower the electrode tips into the solution. Assure that the meter is in the
concentration mode.

3. Adjust the meter to the concentration of the standard and fix the value in the memory
according to the meter manufacturer's instructions.

4. Rinse the electrodes with distilled water and blot dry.

5. To another 150 ml beaker, add 50 ml of methanol-formaldehyde solution and 50 ml of the
higher value standard. Add 2 ml of ISA. Place the beaker on a magnetic stirrer and begin
stirring at a constant rate. Lower the electrode tips into the solution.

6. Adjust the meter to the concentration of the standard and fix the value in the memory.

7. Read the electrode slope according to the meter manufacturer's instructions. Correct
electrode operation is indicated by a slope of 90-100%. See the TROUBLESHOOTING
sections if the slope is not within this range.

MEASUREMENT

Measuring Hints

All samples and standards should be at the same temperature for precise measurement. A difference
of 1oC in temperature will result in a 4% measurement error.

Constant, but not violent stirring is necessary for accurate measurement. Magnetic stirrers can
generate sufficient heat to change the solution temperature. To counteract this effect, place a piece
of insulation material, such as styrofoam sheet, between the stirrer and beaker.

Use plastic lab-ware for all low level measurements in order to minimize absorption on container
walls. Always rinse the electrodes with distilled water and blot dry between measurements. Use a
clean, dry tissue to prevent cross-contamination.

To prevent oxidation of the membrane, always use methanol-formaldehyde solution to mix with all
standards and samples.

For samples with high ionic strength, prepare standards whose composition is similar to the sample.
Dilute concentrated samples (>0.1M) before measurement.

Use fresh standards for calibration. Use 2 ml of ISA for each 100 ml of sample or standard.

Always check to see that the membrane is free from air bubbles after immersion into the standard or
sample.

Sample Requirements

All samples must be aqueous and not contain organics which can dissolve the epoxy electrode body
and/or the cement bonding the sensing crystal to the electrode body. Infrequent measurements in
solutions containing methanol, benzene, or acetonitrile are permitted. Highly polar solvents slowly
attack the electrode. Please check with Eutech Instruments Pte Ltd. before using these electrodes in
other organic solvents.

Instruction Manual Lead Electrode

5

The temperature of the standard solutions and of the sample solutions should be the same and below
80oC. About a 4% error in the slope will occur for each 1oC difference in temperature.

Interferences should be absent. If they are present, use the procedure found in the Interferences
and Electrode Response sections to remove them.

Units of Measurement

Lead concentrations are measured in units of ppm as lead, moles per liter, or any other convenient
concentration unit. Table 1 indicates some concentration units and conversion factors.

TABLE 1: Concentration Unit Conversion Factors

ppm Pb+2 M ppm SO

4

-2

20.7 1.0X10

-4

9.6

207.0 1.0X10

-3

96.0

2070.0 1.0X10-2 960.0

MEASUREMENT PROCEDURE

Direct Measurement

Direct measurement is a simple procedure for measuring a large number of samples. A single meter
reading is all that is required for each sample. The ionic strength of samples and standards should
be made the same by adjustment with ISA. The temperature of both sample solution and standard
solution should be the same.

Direct Measurement of Lead (using a pH/mV meter)

1. By serial dilution, prepare 10-2M, 10-3M, and 10-4M or 100 ppm and 10 ppm standards,
from the 0.1M or 1,000 ppm standards. Prepare standards with a composition similar to
the samples if the samples have an ionic strength above 0.1M.

2. Place 50 ml of the 10-4M or 10 ppm standard in a 150 ml beaker and add 50 ml of
methanol-formaldehyde solution. Place the beaker on the magnetic stirrer and begin
stirring at a constant rate. Add 2 ml of ISA. After assuring that the meter is in the mV
mode, lower the electrode tips into the solution. When the reading has stabilized, record
the mV reading.

3. Place 50 ml of the 10-3M or 100 ppm standard in a 150 ml beaker and add 50 ml of
methanol-formaldehyde solution. Place the beaker on the magnetic stirrer and begin
stirring. Add 2 ml of ISA. After rinsing the electrodes with distilled water, blot dry, and
immerse the electrode tips in the solution. When the reading has stabilized, record the mV
reading.

4. Place 50 ml of the 10-2M or 1,000 ppm standard in a 150 ml beaker and add 50 ml of
methanol-formaldehyde solution. Place the beaker on the magnetic stirrer and begin
stirring. Add 2 ml of ISA. After rinsing the electrodes with distilled water, blot dry, and
immerse the electrode tips in the solution. When the reading has stabilized, record the mV
reading.