pH meter use and maintenance details
one, pH meter calibration and activation
1. Calibration method: For the specific calibration method, please refer to the product manual.
2. Activation method: After using the electrode for a period of time, if you find that the slope becomes lower and the response speed becomes slower, you can try the following methods
(1) If the measured sample contains protein, the electrode membrane can be cleaned with pepsin/hydrochloric acid lotion;
(2) If the measured sample is an oily/organic liquid, it can be washed with acetone or ethanol;
(3) If the junction of the electrode is found to be dirty and black, the junction can be cleaned with mercaptan cleaning solution;
(4) If the electrode membrane becomes dry, soak it in 0.1M HCl for 12 hours, and then soak it in 3M KCl solution for 24 hours.
3. Calibration frequency: In principle, the pH meter is calibrated once, and the instrument does not need to be calibrated again within 48 hours for frequently used pH meters. In case of any of the following situations, the instrument needs to be re-calibrated
(1) When there is a large difference between the solution temperature and the calibration temperature;
(2) The electrode is exposed to the air for too long, such as when more than 0.5h;
(3) After measuring the solution of overacid (pH<2) or overalkaline (pH>12);
(4) When the pH value of the measured solution is not in the middle of the selected solution during two-point calibration, and it is far away from (pH)7.
Two, the correct use of pH meter
1. Before use, check the bulb at the front of the glass electrode. Under normal circumstances, the electrode should be transparent without cracks; the bulb should be filled with solution without air bubbles.
2. The electrode cannot be used in other corrosive solutions such as strong acid and strong alkali, or in dehydrating media (such as absolute ethanol, potassium dichromate, etc.).
3. When measuring a solution with a high concentration, shorten the measurement time as much as possible, and wash it carefully after use to prevent the measured liquid from adhering to the electrode and polluting the electrode.
4. When measuring, the leading wire of the electrode should keep still, otherwise it will cause unstable measurement.
Third, the correct maintenance method of pH meter
1. When the pH meter is not in use, fully immerse the electrode in 3M KCl solution, but avoid immersing in distilled water.
2. After cleaning the electrode, do not wipe the glass membrane with filter paper, but use filter paper to dry it to avoid damage to the glass membrane, prevent cross-contamination, and affect the measurement accuracy.
