User manual EUTECH INSTRUMENTS BROMIDE EPOXY

[. . . ] Instruction Manual Bromide Electrode EUTECH INSTRUMENTS PTE LTD. INSTRUCTION MANUAL BROMIDE ION ELECTRODE 1 Instruction Manual Bromide Electrode TABLE OF CONTENTS GENERAL INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Required Solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 GENERAL PREPARATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrode Preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrode Slope Check (with a 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] A reading differing by more than 0. 5 mV or a change in the ambient temperature will necessitate the repetition of steps 2-6 above. 5. 6. 7. 8. 9. 10. Low Level Bromide Determinations (using a pH/mV meter) This procedure is recommended for solutions containing less than 2. 0X10-6M (0. 2 ppm). Use the following low level bromide measurement procedure in the non-linear portion of the calibration curve. Using 20 ml of the standard ISA, dilute to 100 ml with distilled water. This low level (1. 0M NaNO3) is added at the rate of 1 ml low level ISA to each 100 ml of sample. Dilute 1 ml of 0. 1M standard to 1, 000 ml to prepare a 1. 0X10-4M standard solution for measurements in moles per liter. Dilute 10 ml of 1, 000 ppm standard to 1, 000 ml to prepare a 10 ppm standard solution for measurements in ppm. Add 1 ml of low level ISA, place the beaker on the magnetic stirrer, and begin stirring at a constant rate. 2. 3. 8 Instruction Manual Bromide Electrode 4. Place the rinsed, dried electrode tips in the solution and assure that the meter is in the mV mode. 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 Bromide Measurements Added Volume (ml) 0. 1 0. 1 0. 2 0. 2 0. 4 2. 0 2. 0 Concentration M ppm -7 1. 0X10 0. 01 2. 0X10-7 0. 02 -7 4. 0X10 0. 04 6. 0X10-7 0. 06 -7 9. 9X10 0. 99 2. 9X10-6 2. 90 4. 80 4. 8X10-6 5. 6. Step 1 2 3 4 5 6 7 Pipet A A A A A B B Pipet A = 1 ml graduated pipet Pipet B = 2 ml pipet Solutions: additions of 1. 0X10-4M or 10 ppm standard to 100 ml of solution as 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. Measure out 100 ml of sample into a 150 ml beaker, add 1 ml of low level ISA. Place the beaker on the magnetic stirrer and begin stirring at a constant rate. After the reading has stabilized, record the mV reading and determine the concentration from the low level calibration curve. Check the calibration curve every 1-2 hours by repeating Steps 2-7 above. 8. 9. 10. 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. 9 Instruction Manual Bromide Electrode Interferences A layer of silver may form on the electrode surface in the presence of strong reducing agents. Insoluble salts of silver may be deposited on the membrane, causing electrode malfunction if high levels of ions forming these salts are present in the sample. Solutions containing oxidizing agents such as MnO4-1, Fe+3 and Cu+2, may be measured without problem. [. . . ] Electrode charge will be carried unequally across the solution boundary resulting in a potential difference between the two solutions, since 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. 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. [. . . ]