Acidity meter referred to as ph meter use method and precautions
1. Proper use and maintenance of electrodes The electrodes currently used in the laboratory are composite electrodes, which have the advantages of being easy to use, not affected by oxidizing or reducing substances, and have a faster equilibrium speed. When in use, remove the rubber sleeve on the electrode filling port and the rubber sleeve at the lower end to maintain the hydraulic pressure difference of the potassium chloride solution in the electrode. The following is a brief introduction to the use and maintenance of the electrode: 1. When the composite electrode is not in use, it can be fully immersed in 3m potassium chloride solution. Do not soak with washing liquid or other water-absorbing agents.
2. Before use, check the bulb at the front end of the glass electrode. Under normal circumstances, the electrode should be transparent without cracks; the bulb should be filled with solution without air bubbles.
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. After cleaning the electrode, do not wipe the glass membrane with filter paper, but use filter paper to dry it, so as to avoid damage to the glass membrane, prevent cross-contamination, and affect the measurement accuracy.
5. During the measurement, pay attention to the silver-silver chloride internal reference electrode of the electrode should be immersed in the chloride buffer solution in the bulb to avoid digital jumping in the display part of the electric meter. When using, pay attention to gently shake the electrode a few times.
6. The electrode cannot be used in strong acid, strong alkali or other corrosive solutions.
7. It is strictly forbidden to use in dehydrating medium such as absolute ethanol, potassium dichromate, etc.
2. Preparation and storage of standard buffer solution
1. The ph standard substance should be stored in a dry place. For example, the mixed phosphate ph standard substance will deliquesce when the air humidity is high. Once deliquescence occurs, the ph standard substance cannot be used.
2. Secondary distilled water or deionized water should be used to prepare ph standard solution. If it is used for 0.1 level ph meter measurement, ordinary distilled water can be used.
⒊ The prepared pH standard solution should be diluted with a smaller beaker to reduce the pH standard solution sticking to the beaker wall. In addition to pouring out the plastic bags or other containers that store pH standard substances, they should also be rinsed with distilled water several times, and then poured into the prepared pH standard solution to ensure that the prepared pH standard solution is accurate.
4. The prepared standard buffer solution can generally be stored for 2-3 months. If turbidity, mold or precipitation are found, it cannot be used any longer.
5. Alkaline standard solution should be sealed and stored in polyethylene bottles. Prevent carbon dioxide from forming carbonic acid after entering the standard solution and lower its pH value.
