What is the calibration method of the acid-base concentration meter
The calibration method adopts the two-point calibration method, that is, two standard buffer solutions are selected:
One is the pH7 standard buffer.
The second is pH9 standard buffer or pH4 standard buffer. First use the pH7 standard buffer solution to position the electrometer, and then select the second standard buffer solution according to the acidity and alkalinity of the solution to be tested.
If the solution to be tested is acidic, use a pH4 standard buffer; if the solution to be tested is alkaline, use a pH9 standard buffer. If it is a manually adjusted pH meter, it should be operated several times between the two standard buffer solutions until it is no longer necessary to adjust its zero point and positioning (slope) knobs, and the pH meter can accurately display the pH values of the two standard buffer solutions. Then the calibration process ends.
When calibrating, pay attention to:
The temperature of the standard buffer solution should be as close as possible to the temperature of the tested solution.
The positioning standard buffer solution should be as close as possible to the pH value of the solution to be measured. Or two-point calibration, try to make the pH value of the measured solution within the interval of the two standard buffer solutions.
After calibration, the electrode immersed in the standard buffer solution should be specially rinsed with water, because the buffering effect of the buffer solution will cause measurement errors after being brought into the measured solution.
When recording the pH value of the measured solution, the temperature value of the measured solution should be recorded at the same time, because the pH value is almost meaningless without the temperature value. Although most pH meters have a temperature compensation function, it only compensates the response of the electrode, that is to say, it is only half-compensated, and does not perform temperature compensation on the measured solution at the same time, that is, full compensation.
