User manual EUTECH INSTRUMENTS SODIUM GLASS

[. . . ] Instruction Manual Sodium Electrode EUTECH INSTRUMENTS PTE LTD. INSTRUCTION MANUAL SODIUM ION ELECTRODE Sodium Electrode Instruction Manual TABLE OF CONTENTS GENERAL INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 REQUIRED EQUIPMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 REQUIRED SOLUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 GENERAL PREPARATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 ELECTRODE PREPARATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 ELECTRODE SLOPE CHECK (WITH PH/MV METER) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 ELECTRODE SLOPE CHECK (WITH ION METER) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 MEASUREMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 MEASURING HINTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 SAMPLE REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 UNITS OF MEASUREMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 MEASUREMENT PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] Adjust the meter to the concentration of the sodium standard and fix the value in the memory according to the meter manufacturer's instructions after stabilization of the reading. Place the more concentrated solution on the magnetic stirrer and begin stirring at a constant rate. Adjust the meter to the concentration of the sodium 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 electrodes 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 the beaker on the magnetic stirrer, and begin stirring. 2. 3. 4. 5. 6. 7. 8. 5 Sodium Electrode Instruction Manual 9. After rinsing the electrodes and blotting dry, place the electrode tips in the solution and wait for the reading to stabilize. Assuming no change in ambient temperature, place the electrode tips in the first sodium standard. After the reading has stabilized, compare it to the original reading recorded in Step 4 above. A reading difference by more than 0. 5 mV or a change in the ambient temperature will necessitate the repetition of Steps 2-8 (9) above. The meter should be recalibrated daily. 10. Low Level Sodium Determination (using a pH/mV meter) This procedure is recommended for solutions with ionic strength less than 1. 0X10-2M and a sodium concentration less than 1X10-5M or 1 ppm. If the solution is high in ionic strength, but low in sodium, use the same procedure, but prepare a calibration solution with a composition similar to the sample. Dilute 20 ml of the outer chamber filling solution to 100 ml with distilled water and fill the reference electrode if using a double junction reference electrode. 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 solution to 100 ml to prepare a 100 ppm standard solution for measurements in ppm. Using a 150 ml plastic 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. 5. 7. TABLE 2: Step-wise Calibration for Low Level Sodium Measurements Added Volume (ml) 0. 1 0. 1 0. 2 0. 2 0. 4 2. 0 2. 0 Concentration M ppm -6 1. 0X10 0. 10 2. 0X10-6 0. 20 -6 4. 0X10 0. 40 6. 0X10-6 0. 60 -6 9. 9X10 0. 99 2. 9X10-5 2. 91 -5 4. 8X10 4. 76 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. 0X10-3M or 100 ppm standard to 100 ml of distilled water and 1 ml of low level ISA. 6 Instruction Manual Sodium Electrode 8. On semi-logarithmic graph paper, plot the millivolt reading (linear axis) against the concentration (log axis) as in Figure 1. To a 150 ml plastic beaker add 100 ml of sample and 1 ml of low level ISA. After the reading has stabilized, record the mV reading and determine the concentration from the low level calibration curve. [. . . ] When two solutions of different compositions are brought into contact with one another, liquid junction potentials arise. Millivolt potentials occur from the inter-diffusion of ions into the two solutions. 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. [. . . ]