Introduction to how to extend the service life of pH meter electrodes
1. Correct selection of pH buffer solution
A pH buffer solution is a solution that can maintain a stable pH value under normal circumstances. Even if a small amount of acid or alkali is added to this solution, the pH value of the solution remains basically constant. This solution that can resist a small amount of acid-base interference and maintain a constant pH value is called a pH buffer solution.
⑴ The pH meter should be calibrated at least once a day before use, such as using the buffer solution pH 4.00 commonly used in national standard textiles, pH6.86, pH9.18, One point calibration, two-point calibration, three-point calibration can be used. Generally, pH meters have options, and under normal circumstances, there are at least a few standard buffer solution groups from China, Japan, and the United States, or 1, 2, and 3 component options
⑵ It is generally used for calibrating or verifying pH meters, such as the buffer solutions pH 4.00 and pH 6.86 commonly used in national standard textiles. After calibrating the pH meter, the pH electrodes are inserted into pH 9.18 and pH 4.00 buffer solutions respectively to verify whether the displayed value of the pH meter is the same as the pH value of the standard solution
2. When not in use, soaking method for pH electrode
The pH electrode should be soaked before use. The pH bulb is a special glass membrane. There is a very thin hydrated gel layer on the surface of the glass membrane. It can respond well to H+ions in the solution only when it is fully wetted. Meanwhile, soaking the glass electrode can greatly reduce the asymmetric potential and stabilize it. Usually, a 3.3mol/L KCL solution is used, and the soaking time is generally more than 12 hours. However, to avoid crystallization of the 3.3mol/L KCL solution, it can be washed away with distilled water and cannot be scraped off with other tools
3. Precautions for using the composite electrode of pH meter
① Before testing, check the electrode bubble. There should be no bubbles at the front end of the bubble. If there are bubbles, they should be thrown away slightly with force.
② After removing the electrode from the soaking solution, it can be cleaned in third grade water. Do not wipe the bulb with a tissue, otherwise the static induced charge will transfer to the glass film, which will prolong the time for the potential to stabilize. Alternatively, the electrode can be directly rinsed with the test solution.
③ The pH composite electrode should be inserted into the tested solution at least 1cm or less. Before testing, stir it several times and then let it stand still. This will accelerate the response speed of the electrode and stabilize the test value.
