How to maintain the ph meter
1. Storage of pH glass electrode
Short-term: stored in buffer solution with pH=4;
Long term: stored in buffer solution with pH=7.
2. Cleaning of pH glass electrode
Contamination of glass electrode bulb may prolong the electrode response time. You can wipe off the dirt with CCl4 or soap solution, and then immerse it in distilled water for one night and then continue to use it. When the pollution is serious, it can be soaked in 5%HF solution for 10 ~ 20 minutes, washed with water immediately, and then immersed in 0.1N HCl solution for one day and night before continuing to use.
3. Treatment of aging of glass electrode
The aging of glass electrode is related to the gradual change of adhesive layer structure. The old electrode has slow response, high membrane resistance and low slope. Etching off the outer rubber layer with hydrofluoric acid can often improve the electrode performance. If this method can be used to remove the inner and outer rubber layers regularly, the life of the electrode will be almost infinite.
4. Storage of reference electrode
The best storage solution for silver-silver chloride electrode is saturated potassium chloride solution. High concentration potassium chloride solution can prevent silver chloride from precipitating at the liquid junction and keep the liquid junction in working condition. This method is also suitable for the storage of composite electrodes.
5. Regeneration of reference electrode
Most of the problems of the reference electrode are caused by the blockage of the liquid junction, which can be solved by the following methods:
(1) Immersion liquid junction: the mixed liquid of 10% saturated potassium chloride solution and 90% distilled water is heated to 60 ~ 70℃, and the electrode is immersed in about 5cm for 20 minutes to 1 hour. This method can dissolve the crystals at the end of the electrode.
(2) Ammonia soaking: When the liquid junction is blocked by silver chloride, it can be soaked with concentrated ammonia water. The specific method is to fill the electrode and clean it, then immerse it in ammonia water for 10 ~ 20 minutes after the liquid is emptied, but don't let ammonia water enter the electrode. Take out the electrode, wash it with distilled water, and add the inner filling liquid again for further use.
(3) Vacuum method: sleeve the hose around the liquid junction of the reference electrode, use a water flow suction pump, and fill the liquid in the suction part through the liquid junction to remove the mechanical blockage.
(4) boiling liquid junction: the liquid junction of the silver-silver chloride reference electrode is immersed in boiling water for 10-20 seconds. Note that the electrode should be cooled to room temperature before the next boiling.
(5) When all the above methods are ineffective, the mechanical method of sandpaper grinding can be used to remove the blockage. This method may cause the ground sand particles to be stuffed into the liquid junction. Causing a permanent blockage.
