User manual EUTECH INSTRUMENTS FLUORIDE EPOXY

[. . . ] Instruction Manual Fluoride Electrode EUTECH INSTRUMENTS PTE LTD. INSTRUCTION MANUAL FLUORIDE ION ELECTRODE 1 Instruction Manual Fluoride Electrode TABLE OF CONTENTS GENERAL INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Required Solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] A new calibration curve should be prepared daily. 7. 7 Instruction Manual Fluoride Electrode Direct Measurement of Fluoride (using an ion meter) 1. By serial dilution of the 0. 1M, 1, 000 ppm, or 100 ppm fluoride standard, prepare two fluoride standards whose concentration is near the expected sample concentration. Add 50 ml of TISAB 1 or TISAB 2, to each 50 ml of standard. When calibrating, assume that the added TISAB has no effect on the standard concentration. Place the more dilute solution on the magnetic stirrer and begin stirring at a constant rate. Assure that the meter is in the concentration mode. Lower the electrode tips into the solution. Adjust the meter to the concentration of the fluoride standard and fix the value in the memory according to the meter manufacturer's instructions after stabilization of the reading. Rinse the electrodes with distilled water and blot dry. Place the more concentrated solution on the magnetic stirrer and begin stirring at a constant rate. Lower the electrode tips into the solution. Adjust the meter to the concentration of the fluoride standard and fix the value in the memory according to the manufacturer's instructions after stabilization of the reading. For low level measurements, place the rinsed, dried electrodes into a solution containing equal volumes of distilled water and TISAB 1 or TISAB 2 (or add 10 ml of TISAB 2 to each 100 ml of distilled water). After stabilization, fix the blank value in the meter according to the meter manufacturer's instructions. After rinsing the electrodes and blotting dry, place the electrode tips into the sample diluted with an equal volume of TISAB 1 or TISAB 2. After stabilization, read the concentration directly from the meter display. The calibration should be checked every 1-2 hours. Assuming no change in ambient temperature, place the electrode tips in the first fluoride 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 ambient temperature will necessitate repetition of Steps 2-8 (29) above. The meter should be re-calibrated daily. 2. 3. 8. 9. 10. 11. Direct Measurement of Fluoride in Water (ASTM D1179, METHOD B) The procedure is used to determine total fluoride concentration in water in ppm. TISAB is added to standards and to samples in order to break fluoride complexes of iron and aluminum, adjust the pH, and provide a constant ionic strength. [. . . ] The reference electrode must also be considered. 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 ions diffuse at different rates. [. . . ]