One point calibration of the pH meter
Any kind of pH meter must be calibrated with a pH standard solution before it can measure the pH value of the sample, and the measurement accuracy is below 0.lpH
The sample can be adjusted by one-point precision method, generally choose pH6.86 or pH7.00 standard buffer. Some instruments have an accuracy of only 0.2pH or 0.1pH, so the instrument only has a ¨positioning¨ adjustment knob. The specific operation steps are as follows:
(1) Measure the temperature of the standard buffer, look up the table to determine the pHs value at this temperature, and adjust the temperature compensation knob to this temperature.
(2) Rinse the electrode with pure water and spin dry.
(3) Immerse the electrode in the buffer solution, shake it, and place it at rest. After the reading is stable, adjust the positioning knob to make the instrument display the pH value of the standard solution.
(4) Take out the electrode, rinse and spin dry.
(5) Measure the sample temperature and adjust the pH meter temperature compensation knob to this temperature value
