Causes for digital instability of pH meter

The pH meter is a common analytical instrument, and there are usually portable pH meters, bench-top pH meters, and pen-type pH meters. The pH meter is widely used to test the pH value of purified water, tap water, domestic water and various liquids.

Causes for digital instability of laboratory pH meter:

1. Check whether the electrode is damaged;

2. The electrode has been used for too long, so please calibrate to see if it is effective;

3. Soak the probe with 2.5mmoL/L KCL solution;

4. Clean the glass ball. It has been used for a long time, and some organic matter is attached to it, resulting in insensitive reaction;

5. There is a chemical balance in the water, and because the general pure water or surface water is weakly alkaline, the balance moves to the positive reaction direction, so the pH will always rise;

6. Add neutral salt to the tested water sample as an ionic strength regulator to change the total ionic strength in the solution, increase the conductivity, and make the measurement fast and stable. When using this method, it must be noted that the added solution should not contain any alkaline or acidic impurities.

The digital pH meter uses potentiometric method to measure the pH value of the solution. The main measuring parts are glass electrode and reference electrode. The glass electrode is sensitive to pH, while the potential of the reference electrode is stable.