Calibration Steps of pH Meter
1. Transfer standard buffer solutions with pH values of 4.01, 7.00, and 10.01 to clean and dry 50mL small beakers.
2. Press the power button to turn on the pH meter, rinse the electrodes clean, dry them with dust-free paper, and place them in a standard buffer solution with a pH of 4.01. Press the "calibrate" button to the CAL.1 interface, wait for the reading to stabilize and the cursor in front of the reading to flash, then press the "number edit" button to adjust the pH meter reading to the pH value of the standard solution. Then press the "calibrate" button to enter the CAL.2 interface.
3. Rinse the electrode clean and dry it with dust-free paper, then place it in a standard buffer solution with a pH of 7.00. Wait for the reading to stabilize and the cursor in front of the reading to flash. Press the "Number Edit" button to adjust the pH meter reading to the pH value of the standard solution. Then press the "calibrate" button to enter the CAL.3 interface.
4. Rinse the electrode clean and dry it with dust-free paper, then place it in a standard buffer solution with a pH of 10.01. Wait for the reading to stabilize and the cursor in front of the reading to flash. Press the "Number Edit" button to adjust the pH meter reading to the pH value of the standard solution.
5. Press the "measure save/print" button to save the calibration result and obtain the slope of the straight line after three-point calibration. If the slope of the straight line is within the range of 100 ± 3 and the pH values of the other two standard buffer solutions are within the range of ± 0.3, then this calibration is valid. Otherwise, recalibration is required.
6. After using the standard buffer solution, seal it with a sealing film and place it in a dry place for multiple uses.
When the pH value of the measured solution is within a small range (such as 3-8), only two standard buffer solutions with pH values of 4.01 and
7.00 can be used for calibration.
After calibration, if the pH meter is frequently used, calibrate it every 2 days. If the following situations occur, the pH meter needs to be recalibrated:
(1) When the electrode is exposed to air for too long, such as more than half an hour.
(2) After measuring the solution with acid (pH<2) or alkali (pH<12).
(3) After changing the electrodes.
