How to use the composite electrode of the pH meter correctly?
⑴ There should be no air bubbles at the front end of the bulb, if there are air bubbles, they should be thrown away with force.
⑵ After the electrode is taken out from the soaking bottle, it should be shaken in deionized water and dried. Do not wipe the bulb with a paper towel, otherwise the time for potential stabilization will be prolonged due to the electrostatic induction of charge transfer to the glass membrane. A better method is to use a Rinse the electrodes with the measuring solution.
(3) After the pH composite electrode is inserted into the solution to be tested, it should be stirred and shaken for a few times and then placed statically, which will speed up the response of the electrode. Especially when using a plastic shell pH composite electrode, the stirring and shaking is more severe, because there will be a small cavity between the bulb and the plastic shell, and after the electrode is immersed in the solution, sometimes the gas in the cavity will produce bubbles if it is too late to get rid of it, making the ball Bubbles or liquid junctions are in poor contact with the solution, so vigorous stirring and shaking is necessary to remove air bubbles.
⑷ After testing in viscous samples, the electrode must be rinsed repeatedly with deionized water several times to remove the sample adhered to the glass membrane. Sometimes it is necessary to wash the sample with other solutions first, then wash with water to remove the solvent, and then immerse in the soaking solution for activation.
⑸Avoid contact with strong acid and alkali or corrosive solutions. If you test such solutions, you should minimize the immersion time and clean them carefully after use.
⑹ Avoid using it in dehydrating media such as absolute ethanol and concentrated sulfuric acid, which will damage the hydrated gel layer on the surface of the bulb.
⑺The shell material of the plastic shell pH compound electrode is PPS. If the electrode shell medium is damaged, the pH compound electrode with a glass shell should be used instead.
What is a pH indicating electrode?
The electrode that responds to the activity of hydrogen ions in the solution and the electrode potential changes accordingly is called a pH indicating electrode or a pH measuring electrode. There are several kinds of pH indicating electrodes, such as hydrogen electrode, antimony electrode and glass electrode, but the most commonly used one is glass electrode. The glass electrode is composed of a glass strut and a hydrogen ion-sensitive glass membrane composed of a special composition. The glass membrane is generally in the shape of a bulb. The bulb is filled with an internal reference solution, inserted into an internal reference electrode (usually silver/silver chloride electrode), sealed with an electrode cap to lead out wires, and fitted with a socket to become a pH indicator. electrode. A single pH indicating electrode cannot be measured, it must be measured together with a reference electrode.
