Correct use and maintenance of composite electrodes
First, the correct use and maintenance of the electrode At present, the electrodes used in the laboratory are composite electrodes, which have the advantages of being convenient to use, not affected by oxidizing or reducing substances, and having a fast balancing speed. When in use, the rubber sleeve and the rubber sleeve at the lower end of the electrode filling port are completely removed 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 used, it can be fully immersed in 3M potassium chloride solution. Do not dip with washing liquid or other water-absorbing reagents. 2. Check the bulb at the front end of the glass electrode before use. Under normal circumstances, the electrode should be transparent without cracks; the bulb should be filled with solution and no bubbles should exist. 3. When measuring a solution with a large concentration, shorten the measurement time as much as possible, and carefully clean it after use to prevent the test solution from adhering to the electrode and contaminating the electrode. 4. After cleaning the electrode, do not wipe the glass film with filter paper, and use filter paper to dry, avoid damage to the glass film, prevent cross-contamination, and affect measurement accuracy. 5. In 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 phenomenon in the display part of the electricity meter. When using, be careful to gently rub the electrode a few times. 6. The electrode should not be used in strong acids, strong bases or other corrosive solutions. 7. It is strictly forbidden to use in dehydrating media such as absolute ethanol, potassium dichromate and the like. Second, the preparation and preservation of standard buffer 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 deliquescent occurs, the pH standard substance cannot be used. 2. Prepare the pH standard solution using double distilled water or deionized water. If it is used for a 0.1-stage pH meter measurement, ordinary distilled water can be used. 3. The pH standard solution should be diluted with a smaller beaker to reduce the pH standard solution on the beaker wall. Plastic bags or other containers for storing pH standards should be rinsed several times with distilled water, 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 be stored for 2-3 months. If it is found to be turbid, moldy or precipitated, it cannot be used any more. 5. The alkaline standard solution should be stored in a polyethylene bottle and sealed. Prevent carbon dioxide from entering the standard solution to form carbonic acid and lower its pH.
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