Is there any time limit for the electrode to be soaked in the solution when using the pH meter?
The pH meter/acidity meter electrode must be soaked before use, because the pH meter/acidity meter bulb is a special glass membrane with a very thin hydrated gel layer on the surface of the glass membrane, which can only be used under fully moist conditions. H+ ions in the solution have a good response. At the same time, the asymmetric potential of the glass electrode can be greatly reduced and stabilized after soaking. The glass electrode of the pH meter/acidometer can generally be soaked in distilled water or pH meter/acidometer 4 buffer solution. It is usually better to use pH meter/acidity meter 4 buffer. The soaking 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 potential of the liquid junction will increase or become unstable. The soaking solution of the reference electrode must be consistent with the external reference solution of the reference electrode, that is, 3.3mol/L KCL solution or saturated KCL solution. The time usually takes a few hours. Therefore, for the pH meter/acidity meter composite electrode, it must be soaked in the pH meter/acidity meter 4 buffer solution containing KCL, so that it can act on the glass bulb and liquid junction at the same time. .Special attention should be paid here, because in the past, people who used a single pH meter/acidity meter glass electrode were accustomed to soaking it in deionized water or pH meter/acidity meter 4 buffer. Later, they still used the pH meter/acidity meter composite electrode. Using such a soaking method, even some incorrect instructions for use with pH meter/acidity meter composite electrodes will provide such wrong guidance. The direct consequence of this wrong soaking method is that a pH meter with good performance will be damaged. The meter/acidity meter composite electrode becomes an electrode with slow response and poor accuracy, and the longer the immersion time, the worse the performance, because after a long period of immersion, the KCL concentration inside the liquid junction (such as inside the sand core) has been greatly reduced. It causes the liquid junction potential to increase and become unstable. Of course, as long as it is soaked again in the correct soaking solution for a few hours, the electrode will still recover.
In addition, pH meter/acidity meter electrodes cannot be immersed in neutral or alkaline buffer solutions. Long-term immersion in such solutions will cause the pH meter/acidity meter glass membrane to respond slowly. Correct pH meter/acidity meter electrode soaking Preparation of solution: Take a pack of pH meter/acidity meter 4.00 buffer (250ml), dissolve it in 250ml pure water, then add 56 grams of analytical grade KCl, heat appropriately, and stir until completely dissolved. There are bottled electrodes on the market The soaking liquid is supplied in two specifications: 500ml and 50ml. These soaking liquids contain preservatives and will not mold or deteriorate. They have a shelf life of one year.
In order to make the pH meter/acidity meter composite electrode more convenient to use, some imported pH meter/acidity meter composite electrodes and some domestic electrodes are equipped with a sealed plastic vial on the head of the pH meter/acidity meter composite electrode, which contains the electrode for soaking. The electrode head is soaked in the liquid for a long time, and it is very convenient to just pull it out and wash it during use. This storage method is not only convenient, but also very beneficial to extending the life of the electrode. However, the soaking liquid in the plastic vial should not be contaminated. Pay attention to replace.
