Maintenance of PH meter (acid meter)

(I) Maintenance 1. Storage of pH glass electrodes For a short period of time: Store in a buffer solution with pH=4; Long term: Store in a buffer solution with pH=7.

2, pH glass electrode cleaning Glass electrode bulb contamination may make the electrode response time longer. Can use CCl4 or soap to remove dirt, and then dip in distilled water and continue using it overnight. When the pollution is serious, it can be soaked with 5% HF solution for 10-20 minutes, rinsed immediately with water, and then immersed in 0.1N HCl solution for a whole day and night.

3. Treatment of Glass Electrode Aging The aging of glass electrodes is related to the gradual change of the adhesive layer structure. The old electrode responds slowly, the membrane resistance is high, and the slope is low. Exfoliating the outer layer with hydrofluoric acid can often improve the electrode performance. If this method can be used regularly to remove the inner and outer layers, the electrode life is almost unlimited.

4. Storage of the Reference Electrode The best storage solution for silver-silver chloride electrodes is a saturated potassium chloride solution. A high concentration of potassium chloride solution can prevent the precipitation of silver chloride at the liquid junction and maintain the liquid junction at work. status. This method is also suitable for storage of composite electrodes.

5, the reference electrode regeneration of the reference electrode occurs most of the problems caused by the liquid junction blockage, can be used to solve the following methods:

(1) Soaking solution junction: Using a mixture of 10% saturated potassium chloride solution and 90% distilled water, heat to 60-70°C, immerse the electrode in about 5 cm, and soak for 20 minutes to 1 hour. This method dissolves the crystallization of the electrode tip.

(2) Ammonia soaking: When the liquid junction is blocked by silver chloride, it can be soaked with concentrated ammonia. The specific method is to wash the electrode and dip the liquid into ammonia water for 10 to 20 minutes after emptying, but do not allow ammonia to enter the interior of the electrode. Take out the electrode and wash it with distilled water. Continue to use it after adding the internal liquid.

(3) Vacuum method: Put the hose on the junction of the reference electrode and use the water suction pump. The liquid in the suction part passes through the liquid junction to remove the mechanical plug.

(4) Boiler fluid junction: The liquid junction of the silver-silver chloride reference electrode is immersed in boiling water for 10 to 20 seconds. Note that the electrode should be cooled to room temperature before the next boiling.

(5) When the above methods are ineffective, the mechanical method of sandpaper grinding can be used to remove the blockage. This method may cause the grinded sand to plug into the liquid junction. Cause permanent blockages.