Why should the pH electrode be soaked? How to properly soak the pH combination electrode?
The pH bulb is a particular glass membrane, and it has a very tiny layer of hydrated gel on its surface that can only interact with the H ions in the solution under completely wet conditions. For this reason, the pH electrode must be soaked before use. There are excellent replies. The glass electrode is also submerged, which tends to stabilize things and significantly lowers the asymmetric potential. Typically, distilled water or a pH4 buffer solution can be used to immerse the pH glass electrode.Generally speaking, it is preferable to use pH4 buffer solution, and the soaking time should be between 8 and 24 hours or longer, depending on the electrode's level of aging and the thickness of the bulb glass membrane. The reference electrode's liquid junction must likewise be simultaneously wet. Since the potential of the liquid junction will rise or become unstable if the liquid connection dries out. The reference electrode's soaking solution must be consistent with its external reference solution, which is 3.3mol/L KCL solution or saturated KCL solution. The soaking period is typically It only takes a few hours.
Correctly soaking the pH composite electrode will enable it to simultaneously work on the glass bulb and the liquid junction. Soak it in the pH4 buffer solution containing KCL. Since individuals used to use a single pH glass electrode and were accustomed to soaking it in deionized water or pH4 buffer solution, special attention needs to be taken here. Later, even with some unreliable pH composite electrodes, they continued to use this soaking technique when using a pH composite electrode. The electrode's instruction manual also provides advice that is incorrect in this regard.A pH composite electrode with good performance will, as a direct result of this incorrect immersion procedure, become an electrode with slow response and poor precision. The longer the immersion duration, the poorer the performance will be because, after a long immersion, the liquid junction will become brittle. Since there is significantly less KCL present inside the border (like in the sand core), the liquid junction's potential is increased and becomes unstable. Naturally, the electrodes will function normally after a brief re-soaking period in the proper soaking solution.
Additionally, buffer solutions that are neutral or alkaline shouldn't be used to soak the pH electrode. The pH glass membrane will react slowly after prolonged exposure to such liquids. The right pH electrode soaking solution is made by dissolving a pack of pH4.00 buffer (250ml) in 250ml of pure water, adding 56 grams of analytically pure KCl, heating the mixture appropriately, and stirring until the KCl is entirely dissolved.
