How to clean the pH electrode?
After contamination at the interface between the bulb and the liquid, first clean with the following solvent, then rinse with deionized water to remove the solvent, and immerse the electrode in the soaking solution for activation.
Pollutant cleaning agent
Inorganic metal oxides below 1mol/L dilute acid
Organic oils and fats as dilute detergents (weakly acidic)
Resin polymer substances, dilute alcohol, acetone, ether
Protein blood cell precipitate acidic enzyme solution (raw food tablets)
Pigment based substances, dilute bleach, hydrogen peroxide
How to repair the pH electrode?
The phenomenon of "damage" to pH composite electrodes is a decrease in sensitivity gradient, slow response, and poor repeatability of readings, which may be caused by the following three factors. Generally, customers can use appropriate methods to repair it:
(1) The electrode bulb and liquid interface are contaminated, and the dirt can be carefully removed using a fine brush, cotton, or toothpick. The protective cover on the head of some molded case electrodes can be unscrewed for easy cleaning. If there is severe pollution, it can be cleaned with a cleaning agent according to the method in Article 8.
(2) The external reference solution is contaminated, and some electrode structures allow for the addition of a solution. At this point, a syringe can be used to extract the external reference solution of the electrode, prepare a new 3.3mol/L or saturated KCl solution, and add it again. Pay attention to the first and second addition, and then extract it again to clean the inner cavity of the electrode.
(3) Aging of glass sensitive film: Soak the electrode bulb in 0.1mol/L dilute hydrochloric acid (9mL hydrochloric acid diluted to 100mL with pure water) for 24 hours, wash with pure water, and then soak the electrode in the soaking solution for 24 hours. If the passivation is severe, the lower end of the electrode can also be immersed in a 45% hydrofluoric acid solution for 3-5 seconds (solution preparation: 4mL hydrofluoric acid diluted to 100mL with pure water), washed with pure water, and then soaked in the electrode immersion solution for 24 hours to restore its performance.
