Correct use and maintenance of the hottest pH mete

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Correct use and maintenance of pH meter

pH meter is abbreviated as pH meter, which is composed of electrode and electricity meter. If the electrodes and thermal insulation materials can be reasonably maintained in use, and they are an integral part of the building thermal insulation system, the standard buffer solution can be prepared according to the requirements and the ammeter can be operated correctly, which can greatly reduce the error of pH indication, so as to improve the reliability of chemical experiments and medical inspection data

I. correct use and maintenance of electrodes at present, the electrodes used in the laboratory are composite electrodes, which have the advantages of convenient use, are not affected by oxidizing or reducing substances, and the balance speed is fast. When in use, remove the rubber sleeve on the liquid filling port of the electrode and the rubber sleeve at the lower end to maintain the hydraulic pressure difference of potassium chloride solution in the electrode

here 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 soak with detergent or other absorbent reagents

2. Before use, check the bulb at the front end of the glass electrode. Under normal conditions, the electrode should be transparent without cracks; The bulb should be filled with solution, and there should be no bubbles

3. When measuring the solution with large concentration, shorten the measurement 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, do not wipe the glass film with filter paper, but dry it with filter paper to avoid damaging the glass film, preventing cross contamination and affecting the measurement accuracy

it is estimated that by 2020 5. In 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, so as to avoid the random jump of the number in the display part of the electrometer. When using, pay attention to gently swing the electrode a few times

⒍ electrode cannot be used in strong acid, strong alkali or other corrosive solutions

II. Preparation and storage of standard buffer

1. PH reference materials should be stored in a dry place. For example, mixed phosphate pH reference materials will deliquesce when the air humidity is high. Once deliquescence occurs, pH reference materials cannot be used. Many electronic tension machines and tools have interchangeable sensors

2. Secondary distilled water or deionized water should be used to prepare pH standard solution. If it is used for 0.1 pH meter measurement, ordinary distilled water can be used

3. When preparing pH standard solution, use a smaller beaker to dilute it, so as to reduce the pH standard solution adhering to the beaker wall. Plastic bags or other containers for storing pH reference materials should be washed with distilled water for many times in addition to being emptied, and then poured into the prepared pH standard solution to ensure the accuracy of the prepared pH standard solution

4. The prepared standard buffer solution can generally be stored for 2-3 months. If turbidity, mildew or sedimentation are found, it cannot be used anymore

⒌ alkaline standard solution should be packed in polyethylene bottles and stored in a closed manner. Prevent carbon dioxide from entering the standard solution to form carbonic acid and reduce its pH value

III. correct calibration of pH meter

ph meter has many types because the designer of the meter will feel headache, nausea, vomiting and other phenomena once smelling it, and its operation steps are different, so the operation of the pH meter should be carried out correctly in strict accordance with its operation instructions. The calibration method of pH meter adopts two-point calibration method, that is, two standard buffers are selected: one is pH7 standard buffer, and the second is PH9 standard buffer or pH4 standard buffer. First, use pH7 standard buffer to locate the electrometer, and then select the second standard buffer according to the acidity and alkalinity of the solution to be tested. If the solution to be tested is acidic, use pH4 standard buffer; If the solution to be tested is alkaline, use PH9 standard buffer. If the pH meter is manually adjusted, it should be operated repeatedly between the two standard buffers for several times until it is unnecessary to adjust its zero point and positioning (slope) knob, and the pH meter can accurately display the pH values of the two standard buffers. The calibration process ends. After that, the zero point and positioning knob should not be moved during the measurement process. If it is an intelligent pH meter, it does not need to be adjusted repeatedly, because the pH values of several standard buffers stored in it can be selected, and can be automatically identified and calibrated. However, attention should be paid to the selection of standard buffer and the accuracy of its preparation

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