User manual EUTECH INSTRUMENTS CYANIDE EPOXY

[. . . ] Instruction Manual Cyanide Electrode EUTECH INSTRUMENTS PTE LTD. INSTRUCTION MANUAL CYANIDE ION ELECTRODE 1 Cyanide 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 pH/mV meter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrode Slope Check (with an ion meter). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 MEASUREMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Measuring Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Sample Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Units of Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 MEASUREMENT PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] Adjust the meter to the concentration of the cyanide standard and fix the value in the memory according to the meter manufacturer's instructions after stabilization of the reading. 7 2. 3. 4. 5. 6. Cyanide Electrode Instruction Manual 7. For low level measurements (below 8X10-6M or 0. 2 ppm), place the rinsed, dried electrodes into a solution containing 100 ml of distilled water and 1 ml ISA. After stabilization, fix the blank value in the meter according to the meter manufacturer's instruction. After rinsing the electrodes and blotting dry, place the electrode tips into 100 ml of the sample and 1 ml of ISA. After stabilization, read the concentration directly from the meter display. Assuming no change in ambient temperature, place the electrode tips in the first cyanide standard. After the reading has stabilized, compare it to the original reading in Step 4 above. A reading differing by more than 0. 5 mV or a change in the ambient temperature will necessitate the repetition of Step 2-10 above. The meter should be re-calibrated daily. 8. 9. Low-Level Cyanide Measurements (using a pH/mV meter) Use the following low level cyanide measurement procedure in the non-linear portion of the calibration curve (below 8X10-6M or 0. 2 ppm). A more accurate electrode indicator technique, such as titration, using a silver/sulfide ion electrode, may be preferred below these levels. By serial dilution, prepare 100 ml of 1. 0X10-3M or 10 ppm cyanide standard from the 1. 0X10-2M or 1, 000 ppm cyanide standard. Using a 150 ml plastic beaker, add 100 ml of distilled water and 1 ml ISA. Place the beaker on the magnetic stirrer and begin stirring at a constant rate. Increments of the standard should be added to the beaker according to the steps outlined in Table 2 below. After the reading stabilizes, record the mV reading for each addition. 2. 3. TABLE 2: Low Level Measurement Calibration Curve Added Volume (ml) 0. 1 0. 1 0. 2 0. 2 0. 4 2. 0 2. 0 Concentration ppm M 0. 01 1. 0X10-6 0. 02 2. 0X10-6 0. 04 4. 0X10-6 0. 06 6. 0X10-6 0. 10 9. 9X10-6 0. 29 2. 9X10-5 0. 48 4. 8X10-5 Step Pipet 1 A 2 A 3 A 4 A 5 A 6 B 7 B Pipet A = 1 ml graduated pipet Pipet B = 2 ml pipet Solutions: additions of 1. 0X10-3M or 10 ppm standard to 100 ml of distilled water and 1 ml ISA 8 Instruction Manual Cyanide Electrode 4. On a semi-logarithmic paper, plot the concentration (log axis) against the millivolt reading (linear axis) as in Figure 1. Place the beaker on the magnetic stirrer and begin stirring at a constant rate. After rinsing the electrodes, blot dry and lower the electrode tips into the solution. After stabilization of the reading, read the mV potential and determine the concentration from the calibration curve. A new low level calibration curve should be prepared daily using fresh standards. 5. ELECTRODE CHARACTERISTICS Reproducibility Electrode measurements reproducible to ±2% can be obtained if the electrode is calibrated every hour. Factors like temperature fluctuations, drift, and noise limit reproducibility. Reproducibility is independent of concentration within the electrode's operating range. Interferences A layer of silver metal may form on the electrode surface in the presence of strongly reducing solutions, such as photographic developer. Ions forming very insoluble silver salts will cause the electrodes to malfunction if present in solution at sufficiently high levels to form a layer of silver salt on the membrane surface. [. . . ] When two solutions of different composition are brought into contact with one another, liquid junction potentials arise. Millivolt potentials occur from the inter-diffusion of ions in the two solutions. Electrode charge will be carried unequally across the solution boundary resulting in a potential difference between the two solutions, since 13 Cyanide Electrode Instruction Manual ions diffuse at different rates. When making measurements, it is important to remember that this potential be the same when the reference is in the standardizing solution as well as in the sample solution or the change in liquid junction potential will appear as an error in the measured electrode potential. [. . . ]