Instruction Manual Chloride Electrode EUTECH INSTRUMENTS PTE LTD.
Instruction Manual Chloride Electrode TABLE OF CONTENTS GENERAL INSTRUCTIONS .......................................................................................................... 3 Introduction..............................................................................................................................................4 Required Equipment.................................................................................................................................
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Instruction Manual Chloride Electrode 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.
Instruction Manual Chloride Electrode 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.
Instruction Manual Chloride Electrode 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.
Instruction Manual Chloride Electrode 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.
Instruction Manual Chloride Electrode 3. Place the mid-range solution (1.0x10-3M or 100 ppm) on the magnetic stirrer and begin stirring. 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 the most concentrated solution (1.0x10-2M or 1,000 ppm) on the magnetic stirrer and begin stirring.
Instruction Manual Chloride Electrode Direct Measurement of Chloride (using a ion meter) 1. By serial dilution of the 0.1M or 1,000 ppm chloride standard, prepare two chloride standards whose concentration is near the expected sample concentration. Measure out 100 ml of each standard into individual 150 ml beakers and add 2 ml of ISA to each. 2. Place the more dilute solution on the magnetic stirrer and begin stirring at a constant rate. Assure that the meter is in the concentration mode. 3.
Instruction Manual Chloride Electrode Low Level Chloride Determination (using a pH/mV meter) Use the following low level chloride measurement procedure in the non-linear portion of the calibration curve. (See Figure 1). This procedure is recommended for solutions containing less than 1.0X10-4M. 1. Using 20 ml of standard ISA, dilute to 100 ml with distilled water. This low level ISA (1.0M NaNO3) is added at the rate of 1 ml low level ISA to each 100 ml of sample. The background ionic strength will be 1.
Instruction Manual Chloride Electrode 9. Measure out 100 ml of the sample into a 150 ml beaker, add 1 ml of low level ISA, and place the beaker on the magnetic stirrer. Begin stirring. Lower the electrode tips into the solution. After the reading has stabilized, record the mV reading and determine the concentration from the low level calibration curve. 10. Prepare a new low level calibration curve daily. Check the calibration curve every two hours by repeating Steps 2-7.
Instruction Manual Chloride Electrode 1. Acidify with 1M HNO3 to pH 4 to remove hydroxide interference. 2. These substances represent complexing species whose maximum level can be exceeded without electrode damage. Value shown represents a 1% error. 3. Add CISA to solutions containing mixed halides to remove interferences. See the procedure below. 4. Add CISA or a solution of Ni+2 to remove sulfide or cyanide interferences.
Instruction Manual Chloride Electrode Chloride ions complex with some metal ions. Table 4 lists the levels of complexing metals causing a 10% error at 1.0X10-4M chloride. TABLE 4: Levels of Complexing Agents Causing a 10% Error at 1.0X10-4M Chloride Ion Bi+3 Cd+2 Mn+2 Pb+2 Sn+2 Tl+3 Concentration 4.0X10-4M (80 ppm) 2.0X10-3M (200 ppm) 2.0X10-2M (1100 ppm) 2.0X10-3M (400 ppm) 6.0X10-3M (700 ppm) 4.
Instruction Manual Chloride Electrode The time needed to reach 99% of the stable electrode potential reading, the electrode response time, varies from several seconds in highly concentrated solutions to several minutes near the detection limit. (Refer to Figure 2.) A drifting potential reading or a decrease in electrode slope may mean that the electrode membrane needs polishing. To polish the membrane: 1. If using polishing paper, cut off a 1-2" piece and place it face up on the lab bench. 2.
Instruction Manual Chloride Electrode Limits of Detection The upper limit of detection in pure sodium chloride solutions is 1M. In the presence of other ions, the upper limit of detection is above 1.0x10-1M chloride, but two factors influence this upper limit. Both the possibility of a liquid junction potential developing at the reference electrode and the salt extraction effect influence this upper limit.
Instruction Manual Chloride Electrode ELECTRODE THEORY Electrode Operation A chloride ion electrode is composed of a glass or an epoxy body and a silver chloride/silver sulfide membrane. When the membrane is in contact with a solution containing chloride ions, an electrode potential develops across the membrane. This electrode potential is measured against a constant reference potential, using a pH/mV meter or an ion meter.
Instruction Manual Chloride Electrode The composition of the liquid junction filling solution in the reference electrode is most important. The speed with which the positive and negative ions in the filling solution diffuse into the sample should be equitransferent. No junction potential can result if the rate at which positive and negative charge carried into the sample is equal. Strongly acidic (pH = 0-2) and strongly basic (pH = 12-14) solutions are particularly troublesome to measure.
Instruction Manual Chloride Electrode - Use the proper filling solution. - Adjust the pH and the ionic strength of the solution by the use of the proper ISA. - Measure correctly and accurately. - Review TROUBLESHOOTING HINTS. Standards and Reagents Whenever problems arise with the measuring procedure that has been used successfully in the past, be sure to check the standard and reagent solutions. If in doubt about the credibility of any of the solutions, prepare them again.
Instruction Manual Chloride Electrode TROUBLESHOOTING HINTS Symptom Out of Range Reading Possible Causes defective meter Next Step check meter with shorting strap (see meter instruction manual) defective electrode check electrode operation electrodes not plugged in properly plug electrode into position and reset meter reference electrode junction clogged clean junction static electricity wipe plastic meter face with detergent solution meter or stirrer ground meter or stirrer not grounded Nois
Instruction Manual Low Slope or No Slope "Incorrect Answer" (but calibration curve is good) Chloride Electrode standards contaminated or incorrectly made prepare fresh standards ISA not used use recommended ISA standard used as ISA use ISA incorrect scaling of semi-log paper plot millivolts on the linear axis.
Instruction Manual Chloride Electrode SPECIFICATIONS Concentration Range: 1M to 5.0X10-5M (35,500 to 1.8 ppm) pH Range: 2 to 12 Temperature Range: 0o-80oC (80 to 100oC intermittent use) Resistance: <1 Mohm Reproducibility: +/-2% Interferences See section on Interferences Size: 110 mm length; 12 mm diameter; 1 m cable length Storage: Store in chloride solution ORDERING INFORMATION CODE/NO.
