To lay down a standard procedure for operation and calibration of pH meter.
This SOP is applicable for operation and calibration of pH meter used in Quality Control .
Microbiologist shall be responsible to follow the procedure mention in this SOP.
Department Head and QA Head shall be accountable for compliance of this SOP.
Calibration of pH Meter Attachment-I
6.0 OPERATING PROCEDURE:
6.1.1 Before operating the instrument, clean the instrument properly.
6.1.2 Place the instrument on clean and flat surface near a power point.
6.1.3 Connect the unit to 230 V mains power supply.
6.1.4 Switch on the mains.
6.1.5 Press the ON/OFF key, pH meter automatically starts in last mode of operation.
6.1.6 Rinse the electrode with purified water & wipe the electrode.
6.1.7 Dip electrode in sample & show the pH.
6.1.8 After completion of pH clean the instrument.
6.1.9 Record the activity of instrument in log book of pH meter.
- pH meter calibrated daily with pH 1.60, 4.00, 7.00 and pH 9.20 buffer solutions which are purchased readymade.
- Take a capsule or tablet of each buffer and add them into three 100ml volumetric flask and add purified water upto the mark of volumetric flask and filter and we can use them for calibration.
- Check the validity of the buffer solutions before use.
- After calibration do not switch off the pH meter. If done so, again calibrate the pH meter before use.
- To remove excessive water from the electrode gently touches it over with a small piece of tissue paper. Never rub the electrode with tissue paper.
- If pH meter is not in use for more than 48 hours, then immerse the electrode in saturated Potassium Chloride solution for one hour before use.
- Calibration Procedure:
- Press the ON/OFF key, pH meter automatically starts in mode of operation.
- Rinse the electrode with purified water and wipe the electrode.
- Transfer buffer solution into a dry beaker.
- Press the “CAL/MEAS” button to enter calibration mode. The ́CAL/MEAS’ indicate will be shown. The upper display will show the measured reading based on the last calibration while the lower display will indicate the pH standard buffer solution. All testers have dual display during calibration mode, to abort calibration, press the CAL/MEAS button.
- Immerse the electrode in the buffer solution pH 4.00. Wait till the screen shows stable value and press ENTER.
- Rinse the electrode with purified water and immerse in the standard buffer solution pH 7.0 Wait till the screen shows stable value and press ENTER.
- Rinse the electrode with purified water and dip in the standard buffer solution pH 9.20 Wait till the screen shows stable.
- When calibration is over pH meter automatically return to measurement mode.
- Now verify the pH of buffer solutions pH 4.00, 7.00 and 9.20 and record the activity in Daily Calibration Record of pH Meter.
- Verification of pH reading should be with in limit ±05 of standard buffer.
- After verification of pH is over discard the used buffer.
- Report any discrepancy observed during calibration of instrument to Quality Control In-Charge or his designee for corrective and preventive action.
- Quality Control In-Charge or his designee informs the defect to Maintenance Department service engineer to rectify the defect. Affix ‘Under Maintenance’ label on the instrument.
- Calibration should be required after maintenance.
6.4 Precaution and Cleaning:
6.4.1 Wash the electrode and reference junction in purified water.
6.4.2 Do not leave the electrode dry keep the electrode in storage medium.
6.4.3 Do not wipe the glass electrode bulb with any coarse material. Use only tissue paper.
6.4.4 Dissolve the salts deposits by immersing the in a container filled with some tap water for ten to fifteen minutes. Then thoroughly rinse with purified water.
SOP: Standard Operating Procedure
QC: Quality Control
QA: Quality Assurance
9.0 DISTRIBUTION LIST:
Quality Assurance Department
Quality Control Department
10.0 HISTORY OF REVISION:
|Version No.||Date of Revision||Reason for Revision|
Calibration of pH Meter Attachment-I
|Date||Observed pH of buffer solution used||Calibration status||Calibrated by||Checked by|
|pH 4.00 ± 0.05||pH 7.00