Precautions for pH tester
1. Before use ① Under normal circumstances, when the pH meter is used continuously, it needs to be calibrated once a day. Generally, the instrument does not need to be calibrated again within 24 hours. The calibration buffer solution generally uses a solution with pH 6.86 for the first time, and a buffer close to the pH value of the tested solution for the second time. If the tested solution is acidic, the buffer solution should be pH 4.00; if the tested solution is When alkaline, choose pH9.18 buffer. ②The water used to prepare buffer solutions of pH 6.86 and pH 9.18 should be boiled for 15 to 30 minutes in advance to remove dissolved carbon dioxide. Contact with air should be avoided during cooling to prevent carbon dioxide contamination.
2. When using ① When pH meter is measuring pH value, it is necessary to ensure that the bulb of the electrode is completely immersed in the medium to be measured, so that more accurate measurement results can be obtained. ②After adding acid or alkali dropwise to the solution to be measured, it must be mixed evenly before measuring. ③ The temperature should not be too high during the measurement. If the measurement result is not accurate if it exceeds 40 °C, it must be taken out with a beaker and cooled slightly.
3. Maintenance ①If the electrode used in the pH meter is a new electrode or an electrode that has not been used for a long time, it must be soaked in distilled water for several hours before use, so that the asymmetric potential of the pH meter electrode can be reduced to a stable level, thereby Reduce the internal resistance of the electrodes. ②Keep the electrode bulb moist. If it is found to be dry, it should be soaked in 3mol/L potassium chloride solution or slightly acidic solution for several hours before use to reduce the asymmetric potential of the electrode. ③The composite electrode should avoid contact with organic matter. Once contacted or stained, it should be cleaned with absolute ethanol.
