Explanation of the accuracy of restoring the pH electrode of the pH meter
When there is a significant measurement error in the pH electrode of our pH meter, we should know that some factors have already started to affect the pH electrode of the pH meter.
The phenomenon of "damage" to the pH meter composite pH electrode is a decrease in sensitivity gradient, slow response, and poor reading repeatability, which may be caused by 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 ball, or toothpick. The protective cover on the head of some molded pH electrodes can be unscrewed to make cleaning more convenient. If the pollution is severe, cleaning agents can be used according to the previous method.
(2) The external reference solution is contaminated. For rechargeable electrodes, a new KCl solution can be prepared and added. Pay attention to pouring it out again during the first and second addition to clean the electrode cavity.
(3) Aging of glass sensitive film: Soak the electrode bulb in 0. lmol/L diluted hydrochloric acid for 24 hours. Wash with pure water and soak the electrode in a solution for 24 hours. If the passivation is severe, the lower end of the electrode can also be immersed in a 4% hydrofluoric acid solution for 3-5 seconds (solution preparation: 4ml of hydrofluoric acid diluted to 100m1 with pure water), washed with pure water, and then soaked in the electrode immersion solution for 24 hours to restore its performance.
matters needing attention
(1) Prevent the instrument from coming into contact with damp gases. The immersion of moisture will reduce the insulation of the instrument, resulting in a decrease in its sensitivity, accuracy, and stability.
(2) The glass film of the glass electrode ball is extremely thin and easily damaged. Avoid contact with hard objects.
(3) The glass film of the glass electrode should not be stained with oil. If it is accidentally stained with oil, it can be rinsed with carbon tetrachloride or ether first, then rinsed with alcohol, and finally rinsed with distilled water.
(4) Bubbles are not allowed in the potassium chloride solution of the calomel electrode, and there are very few crystals in it to maintain a saturated state. If there is too much crystallization and the pores are blocked, it is best to refill with a new saturated potassium chloride solution.
(5) If the pH meter pointer shakes severely, the glass electrode should be replaced.
