Calibration of pH meters using buffer solutions
Adjust the pH meter with a buffer solution until the indicator correctly reads the pH of the solution. The calibration can be done as follows.
(1) Prepare 2 clean 200 mL beakers of distilled water for cleaning the sensor, pH=4 and pH=7 buffer solutions, and a thermometer to measure the temperature of the buffer solution.
(2) Pour 50 to 100 mL of pH=4 and pH=7 buffer solution into the beakers respectively.
(3) Remove the sensor from the holder. If the sensor is mounted in a submerged holder, remove the sensor holder from the submerged holder along with the protective parts.
(4) Clean the sensor electrode by wiping away water droplets with a degreasing cotton pad and immersing the electrode in a buffer solution of pH=7.
(5) The pH of the buffer solution varies with temperature, measure the temperature of the pH=7 buffer solution, and then compare the measured values.
(6) Turn STD (calibration function key) clockwise or counterclockwise until the pH transmitter displays the same value as measured in step
(5) until the pH transmitter shows the same value as that measured in step (5).
(7) Completely wash off the pH=7 solution from the electrode and immerse the electrode in a pH=4 buffer solution.
(8) Measure the temperature of the pH=4 solution and compare the measured values.
(9) Adjust the SLOPE (Slope of Electrode Response) until the pH transmitter shows the same value as measured in step (5).
(10) Repeat steps (4) to (6) until the pH transmitter displays the correct value. If an accurate pH value is read, the calibration of the buffer is complete.
