Key Points for Use and Maintenance of pH Meter Electrodes
(1) The electrode must be calibrated with a standard buffer solution with a known pH value before measurement, and the closer its pH value is to the measured pH value, the better.
(2) Before the next operation after each calibration and measurement, the electrode should be thoroughly cleaned with distilled water or deionized water, and then cleaned once with the test solution.
(3) After removing the electrode sheath, the sensitive glass bubbles of the electrode should be avoided from coming into contact with hard objects, as any damage or scratching will cause the electrode to fail.
(4) After the measurement is completed, promptly put on the electrode protective cover. A small amount of external reference supplement solution should be placed inside the electrode cover to keep the electrode bubbles moist. Avoid soaking them in distilled water.
(5) The external reference supplement solution for the composite electrode is a 3mol/L potassium chloride solution. The supplement solution can be added through a small hole at the top of the electrode. When the composite electrode is not in use, pull on the rubber sleeve to prevent the supplement solution from drying up.
(6) The lead out end of the electrode must be kept clean to prevent short circuits at both ends of the output, otherwise it will cause measurement errors or failures.
(7) The electrode should be paired with a pH meter with a high input impedance (≥ 1012 Ω) to maintain good characteristics.
(8) Electrodes should avoid prolonged immersion in distilled water, protein solutions, and acidic fluoride solutions.
(9) Avoid contact between electrodes and organic silicone oil.
(10) After long-term use, if the slope of the electrode slightly decreases, the lower end can be soaked in 4% HF (hydrofluoric acid) for 3-5 seconds, washed with distilled water, and then soaked in 0.1mol/L hydrochloric acid solution to restore it.
(11) If the tested solution contains sensitive bubbles that are prone to contamination or special effects that block the liquid interface, causing extreme passivation, there will be a decrease in slope and inaccurate display readings. If this phenomenon occurs, the electrode should be cleaned with an appropriate solution according to the nature of the pollutant to restore its original state.
