Calibrating pH Meters Using Buffer Solutions
Adjust the pH meter with a buffer solution until the indicator reads the correct pH of the solution. Adjustments can be made as follows.
(1) Prepare two 200mL clean beakers, distilled water for cleaning the sensor, pH=4 and pH=7 buffer solutions, and a thermometer for measuring the temperature of the buffer solution.
(2) Pour 50~100mL of pH=4 and pH=7 buffer solutions into beakers respectively.
(3) Remove the sensor from the bracket. If the sensor is installed in the immersion rack, remove the sensor holder together with the protection from the immersion rack.
(4) Clean the sensor electrodes, wipe off the water droplets with absorbent cotton, and immerse the electrodes in the buffer solution with pH=7.
(5) The pH value of the buffer solution changes with the temperature, measure the temperature of the buffer solution with pH=7, and then compare the measured values.
(6) Turn STD (calibration function key) clockwise or counterclockwise until the pH transmitter displays the same value as the value measured in step (5).
(7) Wash off the pH=7 solution on the electrode completely, and immerse the electrode in the buffer solution with pH=4.
(8) Measure the temperature of the pH=4 solution, and compare the measured values.
(9) Adjust SLOPE (electrode response slope) until the pH transmitter displays the same value as the value measured in step (5).
(10) Repeat steps (4)~(6) until the pH transmitter displays the correct value. If the correct pH is read, the buffer calibration is complete.
