The correct use and maintenance of the pH meter

The correct use and maintenance of the pH meter

1. Correct use and maintenance electrode

At present, the electrodes used in the laboratory are composite electrodes. The advantage is that it is convenient to use, it is not affected by oxidation or reduction substances, and the balance is faster. When using, remove the rubber cases on the electrode and the lower rubber jacket to keep it all to keep the hydraulic difference in the potassium chloride solution in the electrode. Let’s introduce the use and maintenance of the electrode below:

When the composite electrode is not used, it can be fully soaked in a 3M potassium chloride solution. Do not immerse with a washing solution or other absorbent reagents.

Before use, check the bubble of the front end of the glass electrode. Under normal circumstances, the electrode should be transparent and no cracks; the bubbles should be filled with solutions, and there must be no bubbles.

When the solution with a large concentration is measured, try to shorten the measurement time, and carefully clean it after use to prevent the contaminated electrode from being adhered to the electrode.

After cleaning the electrode, do not wipe the glass film with a filter paper, and apply filter paper to dry, avoid damaging the glass film, prevent cross -pollution, and affect the measurement accuracy.

In the measurement, the internal reference electrodes of the electrode -to -pine silver chloride should be immersed in the chloride cushioning solution in the bubbles to avoid the number of digital jumping in the display part of the electronometer display. When using, pay attention to throw the electrode a few times.

Electric electrodes cannot be used for strong acid, strong alkali or other corrosive solutions.

It is strictly forbidden to use dehydrated medium such as water -free ethanol and potassium chromate.

Second, the preparation of standard buffer and its preservation

Ph standard substances should be preserved in a dry place. If the standard substance of mixed phosphate pH is highly humid in air, the pH standard substance is not available once a moisture disintegration.

Preparation of pH standard solution should be used for secondary distilled water or deodorded water. If it is used for measurement at a level 0.1 pH, ordinary distilled water can be used.

Preparation of PH standard solutions should be diluted with smaller cups to reduce the PH standard liquid on the wall of the cup. Plastic bags or other containers that store pH standard substances should be rinsed multiple times in addition to being cleaned, and then pour it into the prepaid pH standard solution to ensure the accurate pH standard solution.

The standard standard buffer solution can generally be preserved for 2-3 months. If it is found to have turbidity, mold or precipitation, it cannot be continued.

The alkaline standard solution should be closed in a polyethylene bottle. To prevent carbon dioxide from entering the standard solution to form carbonic acid and reduce its pH value.

Third, the correct calibration of the pH plan

There are many types of pH due to the different design of electrometers, and their operation steps are different. Therefore, the operation of the pH should be carried out strictly in accordance with its instruction manual. In specific operations, calibration is an important step in the operation of PH. The data of Table 1 is the measurement value of the accuracy of level 0.01 and the pH that passes through the measurement and verification. The importance of calibration can be seen from this without school.