Is there a time limit for soaking the electrodes in the solution when using a pH meter
The pH meter/acidimeter electrode must be soaked before use, because the pH meter/acidimeter bulb is a special kind of glass film, and there is a very thin hydrated gel layer on the surface of the glass film, which can have a good response to H+ions in the solution only when it is fully wet. At the same time, the glass electrode can greatly reduce the asymmetric potential and tend to be stable after being soaked. The pH meter/acidimeter glass electrode can generally be soaked with distilled water or pH meter/acidimeter 4 buffer solution. It is better to use pH meter/acidimeter 4 buffer solution, and the immersion time is 8 hours to 24 hours or longer, depending on the thickness of the bulb glass film and the degree of electrode aging. At the same time, The liquid junction of the reference electrode also needs to be soaked. Because if the liquid junction dries up, the liquid junction potential will increase or become unstable. The immersion solution of the reference electrode must be consistent with the external reference solution of the reference electrode, A 3.3mol/L KCL solution or saturated KCL solution is usually sufficient for soaking for a few hours. Therefore, for pH/acidity meter composite electrodes, they must be soaked in a pH/acidity meter 4 buffer solution containing KCL in order to work on both the glass bulb and the liquid interface simultaneously. Special attention should be paid to this because in the past, people used to soak single pH/acidity meter glass electrodes in deionized water or pH/acidity meter 4 buffer solution. Later, this soaking method was still used when using pH/acidity meter composite electrodes, and even incorrect guidance was provided in the user manual of some incorrect pH/acidity meter composite electrodes. This incorrect soaking method has caused problems. The direct consequence is that a high-performance pH/acidity meter composite electrode becomes a slow response and inaccurate electrode, Moreover, the longer the soaking time, the worse the performance, because after a long soaking time, the KCL concentration inside the liquid interface (such as inside the sand core) has greatly decreased, causing an increase and instability in the liquid interface potential. Of course, as long as the electrode is re soaked in the correct soaking solution for a few hours, it will still recover
In addition, pH/acidity meter electrodes should not be immersed in neutral or alkaline buffer solutions. Long term immersion in such solutions can cause the pH/acidity meter glass membrane to respond slowly. The correct preparation of pH/acidity meter electrode immersion solution: Take a package of pH/acidity meter 4.00 buffer (250ml), dissolve it in 250ml of pure water, add 56g of analytical grade KCl, heat it appropriately, and stir until completely dissolved. Bottled electrode immersion solutions are available on the market, with specifications of 500ml and 50ml. These immersion solutions contain preservative components and will not mold or deteriorate, with a shelf life of one year
In order to make the use of pH/acidity meter composite electrodes more convenient, some imported pH/acidity meter composite electrodes and some domestic electrodes are equipped with a sealed plastic bottle at the head of the pH/acidity meter composite electrode, which contains electrode soaking solution. The electrode head is soaked in it for a long time and can be removed and cleaned when in use, which is very convenient. This storage method is not only convenient, but also very beneficial for extending the electrode life. However, the soaking solution in the plastic bottle should not be contaminated and should be replaced carefully
