Methods to reduce measurement errors in pH meters
Using temperature compensation function to reduce measurement errors
Due to the different changes in electrode potential at different temperatures, the pHS-3B-S pH meter is equipped with temperature automatic and manual compensation devices to adapt to pH measurement at various temperature states. Before measurement, it is necessary to check the position of the temperature compensation switch on the back panel of the pH meter. If the temperature automatic compensation function is used, it must be set to the "automatic" position. If the manual temperature compensation method is used, it must be set to the "manual" position to achieve sufficient response to the pH electrode and make the measured acid rain pH data true and reliable.
The temperature compensation on the pHS-3B-S pH meter only compensates for the slope term of the electrode. Therefore, in order to obtain accurate measurement results, the measured precipitation sample and the standard buffer solution should be measured at the same and constant temperature as much as possible.
To reduce pH measurement errors caused by temperature, the temperature probe should be calibrated once a month, and the instrument should also be calibrated after installation, maintenance, and adjustment. The temperature difference between the temperature probe and the standard temperature should not exceed 0.5 ℃.
In order to reduce the measurement error of pH value of precipitation samples, observers should pay special attention to the temperature equilibrium process between the collected precipitation sample and the standard solution in the laboratory during normal observation. A clean surface dish should be covered at the top of the beaker containing the precipitation sample to prevent dust from falling in and contaminating the measured precipitation sample, which may cause measurement errors.
