The damage of pH composite electrode is caused by the following three factors, such as reduced sensitivity gradient, slow response and poor repeatability of reading. The general customers can adopt appropriate methods to repair.

(1) electrode bulb and liquid junction can be contaminated, with a fine brush, a cotton ball or toothpick carefully remove dirt. Some plastic shell pH electrode protection cover can be swirled down, cleaning is more convenient, if the pollution is serious, can be cleaned by the former method.

(2) the external reference solution is polluted. For a rechargeable electrode, a new KCl solution can be prepared. When added, it should be poured out when the first, second time is added, so as to clean the inner cavity of the electrode.

(3) aging of glass sensitive membrane: soak the electrode bulb for 24 hours with 0.lmol/L dilute hydrochloric acid. Wash with pure water and soak the solution with electrode for 24 hours. If the passivation is more serious, the lower end of the electrode can also be immersed in 4% hydrofluoric acid solution for 3~5 seconds (the solution is formulated: 4ml hydrofluoric acid diluted with pure water to 100m1), washed with pure water, and then immersed in the electrode soaking solution for 24 hours to restore its performance.