Standard operating procedure for operation and calibration of pH meter.

 

1.0       Title: Standard operating procedure for operation and calibration of pH meter.

 

       2.0   Purpose: To lay down the procedure for the operation and calibration of pH meter

      pH Measuring system is used as quantitative measure of acidity or alkalinity of

      aqueous solutions.

      It is measured on a scale of 0 to 14.

   In order to obtain the precise measurement, calibration of pH measuring system should be

   carried out at regular intervals.

3.0   Scope:

    This procedure shall be applicable for operation and calibration of pH meter in lab

     at Fermenta Biotech Limited.

4.0   Responsibility:  Research Associate/ Research Scientist.

       5.0 Procedure  

         5.1  Reagents:

         5.1.1    Commercially available standard buffer tablets, pH4.0, 7.0 and 9.2

         5.1.2    Double distilled (D.D) water

5.2   Preparation of Standard Buffer pH 4.0,pH7.0  and pH 9.2

          5.2.1  Buffer solution pH 4.00

   5.2.2  Dissolve one buffer tablet/capsule of pH 4.00 (available from Qualigens Fine Chemicals)

             in100.0 ml of freshly boiled and cooled water.

    5.2.3 Store the solution in stoppered glass bottle and label it to indicate mfg. date and

             expiry. date. The expiry date is normally after 7 days from the day of making the solution.

5.2.4     Buffer solution pH 7.00

          5.2.5  Dissolve one buffer tablet / capsule of pH 7.00

             (available from Qualigens Fine Chemicals)  100.0 ml of freshly boiled and cooled water.

5.2.5          Store the solution in stoppered glass bottle and label it to indicate mfg. date and exp. date.

5.2.7 The expiry date is normally 7 days from the manufacturing date.

            5.2.8  Buffer solution pH 9.20

           5.2.9  Dissolve one buffer tablet / capsule of pH 9.20 (available from Qualigens

                      Fine Chemicals) in 100.0 ml of freshly boiled and cooled water.

 

            5.2.10 Alternately, dissolve pre-dried 3.80g borax A.R. in sufficient water to produce 1000 ml.

                    This solution should be stored, protected from Carbon Dioxide.)                                       

       5.2.11 Store the solution in stoppered glass bottle and label it to indicate manufacturing date                            and expiry date.The expiry date is normally 7 days from the manufacturing date.

 

 

5.3 Calibration :

5.3.1          Connect the instrument to the main power supply point. Switch ON the instrument.

5.3.2          The pH meter LCD  displays -   LAB INDIA INSTUMENTS

                                                                 pH ANALYSER Vx.xx

5.3.3          Remove the electrode from beaker containing D.D. water and rinse it with D.D. water.

5.3.4          Remove the excess water by the soaking it with the tissue paper.

5.3.5          Dip the electrode along with the calibrated thermometer in  Buffer  pH 7.0

5.3.6          Press  ‘CAL 7’        and ‘ENTER’.

5.3.7           LCD displays  offset  = + 0.00V

     5.3.8     LCD displays  ‘ENTER  if stable’

5.3.9                Press ‘ENTER’

5.3.10        LCDdisplays‘Wait Stabilizing’

    5.3.11     LCD displays                                    

pH=7.00  T=25.0 S  mV=-0.000   A1

                                                        

 

 

5.3.12      The 'S’ indication on RHS indicates that the meter has been calibrated with 7.00pH

5.3.13.   Buffer  for standardization and offset of 1mV has been memorized.

5.3.14.    Calibration with Buffer 4.0

5.3.15.    Rinse the pH  probe with DD water and wipe dry with tissue.

5.3.16        Insert pH probe into Buffer 4.0

5.3.17        Press ‘CAL 4’

5.3.18      Display shows ‘ Calibration Over ’ indicating meter is calibrated for pH 4.0.

5.3.19      Calibration with Buffer 9.2.

5.3.20              Rinse the pH  probe with DD water and wipe dry with tissue.

5.3.21               Insert pH probe into Buffer 9.2.

5.3.22              Press ‘CAL 9.2’

5.3.23               Display shows ‘ Calibration Over ’ indicating meter is calibrated for pH 9.2

5.3.24              The display reading of the measuring instrument should show the value 9.20 (± 0.05)

                         and if it does so, the electrode system is functioning correctly.

5.3.25              If the display reading does not indicate pH value of 9.20 (± 0.05) respectively

              repeat the calibration .

5.3.26               After recalibration the instrument should indicate pH value of 9.20 (± 0.05).

    5.4 Operation procedure:     

   5.4.1   pH meter is ready for use. After calibration by the step10.0

    5.4.2   Remove the electrode from beaker containing D.D. water and rinse it with D.D. water.

    5.4.3   Remove the excess water by the soaking it with the tissue paper.

    5.4.4   Insert the pH probe with the temperature sensor in the solution of which the pH needs

                  to be known

     5.4.5  Press ‘pH’ key . The Display  shows the ‘pH’ of the solution and also the ‘Temperature’

               of the solution  

     5.4.6   After calibration, record the results in daily calibration record

6.0 ABBREVIATIONS :

    

7.0 RECORDS : Nil

 

8.0 REFERENCES : pH Meter Manual