Why do PH electrodes need to be soaked before use?
The PH electrode must be soaked before use, because the PH bulb is a special glass membrane. There is a thin layer of hydrated gel on the surface of the glass membrane. It can form a stable H layer on the membrane surface only after full immersion, and can have a stable and good response to H in solution. If the soaking is not sufficient, the response value during measurement will be unstable and drift. The soaking time is generally more than 24 hours.
For PH single glass electrodes, they can be soaked in distilled water or 3.0NKCL solution, while single reference electrodes can only be soaked in 3.0NKCL solution. For PH composite electrodes, desalinated water, distilled water, or a 3.0N solution can be used. If soaked for a long time, a 3.0N KCL solution must be used. Previously, when using PH single glass electrodes, people were accustomed to soaking them in ionized water. However, if using PH composite electrodes and still soaking them in deionized water for a long time, this incorrect soaking method will turn a high-performance PH electrode into a slow response and poor accuracy electrode. Moreover, the longer the soaking time, the worse the performance. This is because after a long soaking, the KCL concentration of the electrode reference system will be greatly reduced, and the liquid interface potential will increase and become unstable.
How long is the service life of PH electrodes?
Regarding the lifespan of electrodes, the national standard (ZBN50003-88) stipulates that "the warranty period of electrodes is as follows: from the manufacturing date indicated on the electrode, when unpacked and used within one year of validity, its performance meets all the requirements of this standard. During the warranty period, if it is found that the electrode cannot function properly due to reasons attributable to the manufacturer, the manufacturer shall be responsible for repair or replacement." Therefore, the warranty period of electrodes is based on the premise that they have not been used, with a period of one year. It is incorrect to generalize that the service life of electrodes is one year. The service life of electrodes is closely related to the medium, and the service life of different media is completely different. In many harsh situations, it may only be used for 2 months. And some better media can be used for about a year or even longer.
