Two misunderstandings of pH meter in use
The pH value of water depends on the amount of dissolved substances, so the pH value can sensitively indicate the change of water quality. The change of pH value has a great impact on the reproduction and survival of organisms. In the process of using the pH meter, many reasons are often encountered, which lead to inaccurate pH values measured by the pH meter, which brings troubles to production and work. Here are some tips for you, I hope it can help you.
Misunderstanding 1 of pH meter in use:
Since the pH meter is used to measure the acidity and alkalinity of the solution, it can also be used to measure the concentration of acid and alkali solutions.
In fact, the pH meter measures the ion activity in the solution, not the concentration of the solution, because the concentration and activity of the solution are different.
Misunderstanding 2 of pH meter in use:
The calibration of the pH meter, many people think that the calibration of the meter should be carried out within the full range, and so should the pH meter.
In fact, it is unrealistic for the electrode of the pH meter to obtain the same accuracy within the full scale range during use. The calibration of the pH meter generally adopts two-point calibration. One point is a standard buffer solution around PH7 to position the pH meter; the other point is to use a standard buffer solution around PH4 or PH9 for calibration according to the use environment (acidic or alkaline).
In addition, special attention should be paid to the temperature of the solution to be tested before calibration. In order to correctly select the standard buffer solution, and adjust the temperature compensation knob on the electrometer panel to make it consistent with the temperature of the solution to be tested.
After the calibration work is finished, the frequently used pH meter generally does not need to be re-calibrated within 48 hours. In case of any of the following situations, the instrument needs to be re-calibrated:
(1) When there is a large difference between the solution temperature and the calibration temperature;
(2) The electrode is exposed to the air for too long, such as more than 0.5h;
(3) The positioning or slope regulator is misoperated;
(4) After measuring the solution of overacid (pH<2) or overalkaline (pH>12);
(5) After changing the electrodes;
(6) When the pH value of the measured solution is not in the middle of the solution selected during two-point calibration, and it is far away from 7PH.
