User manual EUTECH INSTRUMENTS POTASSIUM EPOXY

[. . . ] Instruction Manual Potassium Electrode EUTECH INSTRUMENTS PTE LTD. INSTRUCTION MANUAL POTASSIUM ION ELECTRODE 1 Instruction Manual Potassium Electrode 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 ion meter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 MEASUREMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Measuring Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Sample Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Units of Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 MEASUREMENT PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] Measure out 100 ml of each standard into individual 150 ml beakers and add 2 ml of ISA to each. Place the more dilute solution on the magnetic stirrer and begin stirring at a constant rate. Adjust the meter to the concentration of the potassium standard and fix the value in the memory according to the meter manufacturer's instructions after stabilization of the reading. 7 2. 3. Place the more concentrated solution on the magnetic stirrer and begin stirring at a constant rate. Adjust the meter to the concentration of the potassium standard and fix the value in the memory according to the meter manufacturer's instructions after stabilization of the reading. For low level measurements, place the rinsed, dried electrode(s) into a solution containing 100 ml of distilled water and 2 ml of ISA. After stabilization, fix the blank value in the meter according to the meter manufacturer's instructions. Place 100 ml of the sample and 2 ml of ISA in a 150 ml beaker, place it on the magnetic stirrer, and begin stirring. Immerse the electrode tip(s) in the solution and wait for the reading to stabilize. 8. 9. 10. 11. 12. Low Level Potassium Determination (using a standard pH/mV meter) This procedure is recommended for solutions with ionic strengths less than 1. 0 x 10-2M. If the solution is high in ionic strength, but low in potassium, use the same procedure, but prepare a calibration solution with a composition similar to the sample. Dilute 1 ml of the 0. 1M standard to 100 ml to prepare a 1. 0x10-3M standard solution for measurements in moles per liter. Dilute 10 ml of the 1, 000 ppm standard to 100 ml to prepare a 100 ppm standard solution for measurements in ppm. 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. Add increments of the 1. 0x10-3M or 100 ppm standard as given in Table 2 below. After the reading has stabilized, record the mV reading after each addition. 3. 4. 6. 8 Instruction Manual Potassium Electrode TABLE 2: Stepwise Calibration for Low Level Potassium Measurements Added Step Pipet Volume (ml) 1 A 0. 1 2 A 0. 1 3 A 0. 2 4 A 0. 2 5 A 0. 4 6 B 2 7 B 2 Concentration M ppm 1. 0X10-6 0. 1 -6 2. 0X10 0. 2 4. 0X10-6 0. 4 -6 6. 0X10 0. 6 9. 9X10-6 1. 0 -5 2. 9X10 2. 9 4. 8X10-5 4. 8 Pipet A = 1 ml graduated pipet Pipet B = 2 ml pipet Solutions: additions of 1. 0x10-3M or 100 ppm standard to 100 ml of distilled water 7. 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 the sample into a 150 ml beaker, add 1 ml of low level ISA, and place the beaker on the magnetic stirrer. 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 3-7 above. 8. [. . . ] 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 as nearly equal as possible, that is, the filling solution should be equitransferant. No junction potential can result if the rate at which positive and negative charge carried into the sample is equal. [. . . ]