Calibration Of PH Meter in pharma/pH meter calibration sOP:
Calibration of pH meter in pharmaceuticals is the requirement to get consistent results. pH meters must be calibrated before each measurement in order to ensure highly accurate readings. Furthermore, calibration is done once daily.
There is a need for calibration since glass electrodes cannot provide reproducible electrostatic potentials over longer periods of time.
The calibration of pH meter can be performed in two modes.
- Three point calibration and
- Five point calibration.
The companies are following anyone mode of calibration or as per requirements. Most of the companies preferred 3 point calibration.
There are 5 pH meter calibration solutions.
The three-points mode of calibration contains a pH buffer of pH 4.00, pH 7.00 and pH 10.00.
And, the five points mode of calibration contains a pH buffer of pH 1.68, pH 4.00, pH 7.00, pH 10.00 and pH 12.00.
Procedure for Calibration of pH meter:
3 Point mode of pH calibration:
- Switch on the power supply and turn on the pH meter.
- Ensure that the proper mode of calibration is selected.
- Rinse the electrodes with distilled water. Avoid wiping the electrodes, as this will create an electrostatic charge.
- Select the temperature of 25°C or as required.
- Place the electrode into the pH buffer solution of pH 4.00.
- Allow the display to stabilize the reading.
- Set the display to read pH 4.00 by adjusting the knob.
- Rinse the electrode with distilled water for next buffer solution.
- Similarly perform the procedure for remaining two pH buffer solution. (pH 7.00 and pH 10.00)
5 Point mode of pH calibration:
- Perform the same procedure as mentioned in 3 point calibration including pH 1.68 buffer and pH 12.00 buffer.
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