User manual EUTECH INSTRUMENTS CADMIUM EPOXY

[. . . ] Instruction Manual Cadmium Electrode EUTECH INSTRUMENTS PTE LTD. INSTRUCTION MANUAL CADMIUM ION ELECTRODE 1 Cadmium Electrode Instruction Manual TABLE OF CONTENTS GENERAL INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Required Solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 GENERAL PREPARATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrode Preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrode Slope Check (with a pH/mV meter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrode Slope Check (with ion meter). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 MEASUREMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Measuring Hints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Sample Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Units of Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 MEASUREMENT PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] This low level ISA (1. 0M NaNO3) is added at the rate of 1 ml low level ISA to each 100 ml of solution. The background ionic strength will be 1. 0X10-2M. Dilute 1ml of 0. 1M standard to one liter to prepare a 1. 0X10-4M solution for measurements in moles per liter. Prepare a 10 ppm standard solution by diluting 1ml of the 1, 000 ppm standard to 100 ml of solution for measurements in ppm. Standards should be prepared fresh daily. To a 150 ml beaker add 100 ml of distilled water and 1 ml of low level ISA. Place the beaker on the magnetic stirrer and begin stirring at a constant rate. Place the electrode tips in the solution. Add increments of the 1. 0X10-4M or 10 ppm standard as given in Table 2 below. After the reading has stabilized, record the mV reading after each addition. TABLE 2: Step-wise Calibration for Low Level Cadmium Measurements 8 2. 3. 4. 6. Instruction Manual Cadmium Electrode Step 1 2 3 4 5 6 7 Pipet A A A A A B B Added Volume (ml) 0. 1 0. 1 0. 2 0. 2 0. 4 2. 0 2. 0 Concentration ppm M 0. 01 1. 0X10-7 0. 02 2. 0X10-7 0. 04 4. 0X10-7 0. 06 6. 0X10-7 0. 10 9. 9X10-7 0. 29 2. 9X10-6 0. 48 4. 8X10-6 Pipet A = 1 ml graduated pipet Pipet B = 2 ml pipet Solutions: additions of 10 ppm or 1. 0X10-4M standard to 100 ml of solution prepared in Step 3 above. On a semi-logarithmic graph paper, plot the mV reading (linear axis) against the concentration (log axis) as in Figure 1. Rinse the electrodes with distilled water and blot dry. Measure out 100 ml of the sample into a 150 ml beaker and add 1ml of low level ISA. Place the beaker on the magnetic stirrer and begin stirring at a constant rate. 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. Prepare a new low level calibration curve daily. Check the calibration curve every two hours by repeating Steps 3 - 7 above. 8. 9. 10. Low Level Cadmium Determination (using an ion meter) 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 1ml low level ISA to each 100 ml of solution. [. . . ] 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 as nearly equal as possible, that is, the filling solution 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. [. . . ]