The pH meter needs to be used for a long time due to the measurement of samples with different pH values, and the results will have errors. When the measurement error of the pH electrode is large, we should know that some factors have begun to affect the accuracy of the instrument, so we need to calibrate the instrument regularly. So how to quickly restore its measurement accuracy? let's see.
The error phenomenon of the pH meter is the decrease in sensitivity gradient, which is mainly attributed to the "damage" of the composite pH electrode, slow response and poor reading repeatability. Usually we can take appropriate methods to repair it:
1. If the electrode bubble and liquid junction are polluted, you can use cotton balls, fine brushes or toothpicks to carefully remove the dirt. The protective cap on the tip of some pH electrodes with plastic housings can be unscrewed for easier cleaning. If the pollution is serious, the previous method can be used for cleaning.
2. The external reference solution is contaminated. For rechargeable electrodes, a new KCl solution can be prepared and added. It should be poured out during the first few additions to clean the inner cavity of the electrode.
3. Aging of glass sensitive membrane: Soak pH meter electrode bulb in 0.1mol/l dilute hydrochloric acid for 24 hours. Wash with pure water, then soak in electrode solution for 24 hours. If the passivation is serious, you can also immerse the lower end of the electrode in 4% hydrofluoric acid solution for 3-5 seconds, wash it with pure water, and then immerse it in the electrode soaking solution for 24 hours to restore its performance.