Precautions for using pH meter electrodes and what to pay attention to when measuring acidity meter sensors
Before performing the operation, the integrity of the electrodes should be checked first. At present, most of the electrodes used in pH meters are composite electrodes, while the older generation pH meters still use glass electrodes and calomel electrodes. Due to the widespread use of composite electrodes, the following mainly discusses composite electrodes.
At present, there are mainly two types of composite electrodes used in the laboratory: fully enclosed and non enclosed. The fully enclosed type is relatively rare and mainly produced by foreign enterprises. Before using the composite electrode, first check whether the glass bulb has cracks or breakage. If not, use a pH buffer solution for two-point calibration. When the positioning and slope buttons can be adjusted to the corresponding pH value, it is generally considered usable. Otherwise, electrode activation treatment can be carried out according to the user manual. The activation method is to immerse in a 4% hydrogen fluoride solution for about 3-5 seconds, take it out and rinse it with distilled water. Then, soak it in a 0.1mol/L hydrochloric acid solution for several hours, rinse it clean with distilled water, and calibrate it. That is, use a buffer solution with a pH value of 6.86 (25 ℃) for positioning. After adjustment, choose another pH buffer solution for slope adjustment. If it cannot be adjusted, replace the electrode. A non enclosed composite electrode requires an external reference solution, i.e. 3 mol/L potassium chloride solution, to be added inside. Therefore, it is necessary to check whether the potassium chloride solution in the electrode is above 1/3. If not, 3 mol/L potassium chloride solution needs to be added. If the potassium chloride solution exceeds the position of the small hole, shake off the excess potassium chloride solution, place the solution below the small hole, and check for any bubbles in the solution. If there are bubbles, gently tap the electrode to completely expel them.
