procedure for operation and calibration of pH meter

1.0       Purpose          :      

To lay down the procedure for operation and calibration of pH meter.

2.0       Scope              :        

This procedure applies to pH meter with the following details.

3.0       Responsibility:

3.1       The responsibility of operation and calibration of pH meter lies with the Microbiologist  /Analyst.

4.0       Definitions/Abbreviations     : Nil

5.0       Procedure      :

5.1       Operating Procedure of pH Meter:

5.1.1    The pH meter consists of a single electrode capable of reading the pH from 2-13 range, and ATP probe capable of reading the temperature from 0-100° C.

5.1.2    Check whether the connections of electrode and ATP probe are proper or not.

5.1.3Switch on the instrument.

5.1.4LCD shall display “POLMAN” “SELF CHK” and Temperature respectively.

5.1.5The instrument measures pH / mv along with temperature.

5.1.6Keep the instrument in HOLD mode by pressing HOLD key.

5.1.7Calibrate the instrument as per the calibration procedure.

5.1.8After completion of the calibration of the instrument, press HOLD key “SAMPLE” message is displayed.

5.1.9Rinse the electrode and ATC probe (if used) with sufficient purified water and remove excess water by using whatman filter paper.

5.1.10Dip the electrode and ATC probe (if selected auto temp. mode) in the testing sample.

5.1.11Press HOLD key. “WAIT” message is displayed.

5.1.12After stabilization the sample pH is displayed.

5.1.13If manual temperature is selected, check the temperature of the sample by using a calibrated thermometer and adjust the temperature by pressing ?(Up) or ?(down) keys and take the pH reading.

5.1.14Press HOLD key for STD mode, temperature will be displayed in LCD.

5.2       Calibration     :

5.2.1Switch on the instrument and wait for 5 minutes.

5.2.2Commercially available NIST traceable standard pH buffers 4.0, 7.0, and 10.0 shall be used for calibration.

5.2.3Press PRG/CAL button.

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Display shows ‘Password’

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Use up or down key on right hand side of the instrument to select password, press Ok/Hold button.

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            Display shows ‘PRG 1: Calib’, press Ok/Hold button.

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Display shows ‘Auto Temp Calib’, press Ok/Hold button.

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Display shows ‘2 Pt Calib’, press Ok/Hold button.

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Display shows ‘Buf 7 / 4’, dip the electrode in buffer 7, press Ok/Hold button.

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Display shows ‘wait’ and then shows ‘Done’, press Ok/Hold button.

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Display shows buf 4 / 9.2.

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Wash electrode with purified water and then dip the electrode in buffer 4, then press Ok/Hold button.

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Display shows ‘wait’ and then shows “Done 4’, press Ok/Hold button.

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Display shows ‘Sample’, wash the electrode with purified water and dip in Buffer 10.0, then press Ok/Hold button.

              ↓

It will show the pH of the Buffer 10.0

5.2.4The pH meter shall be calibrated at the starting of the day.

5.2.5Record the results as shown in the format.

5.2.6Acceptance criteria: The recorded variation in the pH of the standard buffer shall be within ±0.05 pH units.

5.2.7Usage of standard buffer solution: Take 50 ml of each buffer solutions from QCD and label the solutions with buffer name, B.No. opened date and use before date. Use the solutions for 15 days. If any abnormality found in between like haziness of buffer solution or impact on calibration due to buffer solutions, replace the buffer solutions.

6.0       Related Documents:  Nil.

Ph meter, microbiology, filter paper