How to use and maintain PH meter correctly
Proper use and maintenance of PH electrode
At present, the PH meter electrodes used in the laboratory are all composite electrodes, which have the advantages of convenient use, no influence from oxidizing or reducing substances, and fast balance speed. When in use, the rubber sleeve on the liquid adding port of the PH meter electrode and the rubber sleeve at the lower end are all removed to keep the hydraulic pressure difference of potassium chloride solution in the electrode. Here is a brief introduction to the use and maintenance of electrodes:
1. When the composite electrode is not used, it can be fully immersed in 3M potassium chloride solution. Never use washing liquid or other absorbent reagents to soak and wash.
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, and no bubbles can exist.
3. When measuring the solution with large concentration, shorten the measuring time as far as possible, and carefully clean it after use to prevent the measured solution from adhering to the electrode and polluting the electrode.
4, after cleaning the electrode, don't use filter paper to wipe the glass film, and the application of filter paper to blot, to avoid damage to the glass film, prevent cross contamination, affect the measurement accuracy.
5. During the measurement, pay attention to that the silver-silver chloride internal reference electrode of the electrode should be immersed in the chloride buffer solution in the bulb to avoid the digital jumping phenomenon in the display part of the ammeter. When using, pay attention to gently swing the electrode a few times.
6. The electrode cannot be used in strong acid, strong alkali or other corrosive solutions.
7. It is strictly prohibited to use in dehydrated media such as anhydrous ethanol and potassium dichromate.
Preparation and storage of standard buffer solution
1. The pH reference material should be stored in a dry place. For example, the mixed phosphate pH reference material will deliquesce when the air humidity is high. Once deliquescence occurs, the pH reference material cannot be used.
2. Secondary distilled water or deionized water should be used to prepare the pH standard solution. If it is used for 0.1 grade pH meter measurement, ordinary distilled water can be used.
3. The prepared 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 standard materials should be cleaned, and distilled water should be used for washing for many times, and then poured into the prepared pH standard solution to ensure the accuracy of the prepared pH standard solution.
4. Generally, 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, alkaline standard solution should be packed in polyethylene bottle sealed preservation. Prevent carbon dioxide from forming carbonic acid after entering the standard solution and reduce its pH value.
