EUTECH INSTRUMENTS CHLORIDE ION ELECTRODE Instruction Manual

Instruction Manual Chloride Electrode

1

EUTECH INSTRUMENTS PTE LTD.

INSTRUCTION MANUAL

CHLORIDE ION ELECTRODE

Instruction Manual Chloride Electrode

2

TABLE OF CONTENTS

GENERAL INSTRUCTIONS ..........................................................................................................3

Introduction..............................................................................................................................................4

Required Equipment.................................................................................................................................4

Required Solutions...................................................................................................................................4

GENERAL PREPARATION............................................................................................................5

Electrode Preparation...............................................................................................................................5

Electrode Slope Check (with pH/mV meter) ...........................................................................................5

Electrode Slope Check (with ion meter)..................................................................................................6

MEASUREMENT..............................................................................................................................6

Measuring Hints.......................................................................................................................................6

Sample Requirements...............................................................................................................................7

Units of Measurement..............................................................................................................................7

MEASUREMENT PROCEDURE ................................................................................................... 7

Direct Measurement.................................................................................................................................7

Direct Measurement of Chloride (using a pH/mV meter)........................................................................7

Direct Measurement of Chloride (using a ion meter)...............................................................................9

Low Level Chloride Determination (using a pH/mV meter)................................................................. 10

Low Level Chloride Determination (using an ion meter)......................................................................11

ELECTRODE CHARACTERISTICS........................................................................................... 11

Reproducibility.......................................................................................................................................11

Interferences...........................................................................................................................................11

Removal of Various Interferences with CISA .......................................................................................12

Complexation.........................................................................................................................................12

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

Electrode Response................................................................................................................................13

Limits of Detection ................................................................................................................................15

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

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

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

ELECTRODE THEORY................................................................................................................16

Electrode Operation ...............................................................................................................................16

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

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

Glassware...............................................................................................................................................17

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

Standards and Reagents..........................................................................................................................18

Sample....................................................................................................................................................18

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

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

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

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

Instruction Manual Chloride Electrode

3

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

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

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

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

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

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

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

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

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

RROR! BOOKMARK NOT DEFINED.

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

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

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

Instruction Manual Chloride Electrode

4

EUTECH INSTRUMENTS PTE LTD.

CHLORIDE ION ELECTRODE

INSTRUCTION MANUAL

GENERAL INSTRUCTIONS

Introduction

Eutech Instruments Chloride Ion Electrode is used to measure chloride 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.

3. A magnetic stirrer.

4. Eutech Chloride Ion Combination Epoxy-body Electrode, Code no. EC-CLO-03.

5. 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. Eutech Ionic Strength Adjuster (ISA), 5M NaNO

3

, Code no. EC-ISA-CL1. To prepare this
solution from your own laboratory stock, half fill a 1,000 ml volumetric flask with distilled
water and add 425 grams of reagent-grade sodium nitrate, NaNO

3

. Swirl the flask to
dissolve the solid. Fill the flask to the mark with distilled water, cap, and invert the flask
several times to mix the contents. ISA is added at the rate of 2 ml of ISA to each 100 ml of
standard or sample to adjust the ionic strength to about 0.1M.

3. Eutech Electrode Filling Solution, 1M/0.1M KNO3/KCl, Code no. EC-RE-018, for the EC­CLO-03 chloride combination epoxy electrode. Eutech Electrode Filling Solution, 1M
KNO3 Code No. EC-RE-013, for the ECR-04-HC double junction reference electrode or
the EC-CLO-02 chloride combination glass electrode.

4. Eutech Chloride Standard, 0.1M NaCl, Code no. EC-SCS-CL1-BT. To prepare this
solution from your own laboratory stock, add 5.84 grams of reagent-grade sodium
chloride, NaCl, to a one liter volumetric flask about half-full of distilled water. Swirl the
flask to dissolve the solid. Fill to the mark with distilled water, cap, and upend the flask
several times to mix the solution.

Instruction Manual Chloride Electrode

5

5. Eutech Chloride Standard, 1,000 ppm Cl-1, Code no. EC-SCS-CL2-BT. To prepare this
solution from your own laboratory stock, add 1.65 grams of reagent-grade sodium
chloride, NaCl, to a one liter volumetric flask about half-full of distilled water. Swirl the
flask to dissolve the solid. Fill to the mark with distilled water, cap, and upend the flask
several times to mix the solution.

6. Eutech Chloride Standard, 100 ppm Cl-1, Code no. EC-SCS-CL3-BT. To prepare this
solution from your own laboratory stock, add 0.165 grams of reagent-grade sodium
chloride, NaCl, to a one liter volumetric flask about half-full of distilled water. Swirl the
flask to dissolve the solid. Fill to the mark with distilled water, cap, and upend the flask
several times to 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 reference electrode. Fill the combination electrode or the reference 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 of the meter as
recommended by the meter manufacturer.

Electrode Slope Check (with pH/mV meter)

(Check electrodes each day)

1. To a 150 ml beaker, add 100 ml of distilled water and 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
mV mode, lower the electrode tips into the solution.

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

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

4. Determine the difference between the two readings. A difference of -57±3 mV indicates
correct electrode operation, assuming the solution temperature is between 20o and 25oC.
See the TROUBLESHOOTING section 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.

Instruction Manual Chloride Electrode

6

Electrode Slope Check (with ion meter)

(Check electrodes each day)

1. Prepare standard chloride solutions whose concentrations vary by tenfold. Use either the

0.1M or 1,000 ppm chloride standard. Use the serial dilution method for this preparation.

2. To a 150 ml beaker, add 100 ml of the lower value standard and 2 ml of ISA. Place the
beaker on the 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 100 ml of the higher value standard and 2 ml of ISA. Place
the beaker on the 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
section 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 1

o

C in temperature will result in about a 2% 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 insulating material, such as styrofoam sheet, between the stirrer and beaker.

Always rinse the electrodes with distilled water and blot dry between measurements. Use a clean,
dry tissue to prevent cross-contamination.

For samples with high ionic strength, prepare standards whose composition is similar to the sample.
Always check to see that the membrane is free from air bubbles after immersion into the standard or
sample.

Instruction Manual Chloride Electrode

7

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, ethanol, benzene, and acetonitrile are permitted. Highly polar
solvents slowly attack the electrode. Please check with Eutech Instruments Pte Ltd. before using the
electrode in other organic solvents.
The temperature of the standard solutions and of the sample solutions should be the same and
below 50

o

C.

Interferences should be absent. If they are present, use the procedures found in the

Interferences

and Electrode Response sections to remove them.

The pH range for the chloride ion electrode is 2-12. Neutralize samples outside this range with acid
or base to bring them in range.

Units of Measurement

Chloride concentrations are measured in units of parts per million, equivalents per liter, moles per
liter, or any other convenient concentration unit. Table 1 indicates some of the concentration units.

TABLE 1: Concentration Unit Conversion Factors

ppm Cl-1 moles/liter Cl

-1

354.50 1.0X10-2

35.45 1.0X10-3

3.55 1.0X10-4

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 for all chloride solution. The temperature of both sample
solution and of standard solutions should be the same.

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

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

2. Place the most dilute solution (1.0x10

-4

M or 10 ppm) on the magnetic stirrer and begin
stirring at a constant rate. 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.