Operation and Calibration of pH Meter/ Conductivity Meter

pH meter / conductivity meter calibration procedure | 5 points pH meter calibration procedure | Labindia pico pH meter Operation and Calibration |

• SOP covers below points:
  • Operation of pH meter
  • Operation of conductivity meter
  • Calibration of pH meter
  • Calibration of conductivity meter
  • Calibration format for pH meter
  • Calibration format for Conductivity meter

1.0 OBJECTIVE :

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

2.0 SCOPE :

• This procedure is applicable for LAB INDIA make pH/CON Meter.

3.0 RESPONSIBILITY :

• Quality Control Chemist and above

4.0 ACCOUNTABILITY:

• Quality Control Head

5.0 PROCEDURE :

• The pH meter/ Conductivity meter is standardized by using the aqueous buffer solutions/ potassium chloride standard solution and after standardization; the same standardized pH meter/ conductivity meter is used to measure pH/ conductivity of a solution.

5.1 SOLUTION PREPARATIONS

• Use readymade standard buffer solution for pH meter calibration
• Standard buffer solution: pH 1.68, pH 4.01, pH 7.00, pH 9.18 and pH 12.45.

• Prepare 0.001M potassium chloride standard solution for conductivity meter calibration
• Prepare 0.001M potassium chloride standard solution as follows:
  • Weigh accurately 0.0750 gm of Potassium chloride in 100 ml volumetric flask, dissolve and dilute to 100 ml with distilled water. Dilute 10 ml of this solution to 100 ml with distilled water.
• Enter the details of preparation in preparation record.
• Frequency for preparation of potassium chloride solution: Fourth nightly
• The numbering system of potassium chloride solution preparation is as follows;
  • C/YY/ZZ
  • Where,  
  • C    : for Conductivity
  • YY  : for serial number of preparation of buffer solution
  • ZZ  : for the year in which the buffer solution prepared
• The label for preparation of KCl solution shall be affixed on the buffer bottle and it should be updated with current details once change the solution (Annexure No.: 03)

5.2 OPERATION OF pH METER

• Ensure that pH meter is calibrated.
• Raise the electrode from the storing solution (3 M Potassium Chloride).
• Wash the electrode with smooth jet of distilled water and blot dry with tissue paper.
• Press the Reset displays shown;

• Press mode

• Then press 1 and ENTER key. Again press  ENTER key

• Display as

• Immerse the electrode in sample solution so as to dip electrode bulb.
• Now press enter and allow the stable value to come.
• When stable value is come go into GLP mode and press enter.
• Instrument displays as sample name.  Enter the appropriate sample name, then press enter.
• Now again instrument displays as ID No.  Enter the appropriate ID No. and then press enter.

5.3 OPERATION OF CONDUCTIVITY METER

• Ensure that Conductivity meter is calibrated.
• Raise the electrode from the storing solution (Distilled water).
• Wash the electrode with smooth jet of distilled water and blot dry with tissue paper.
• Press the Reset displays shown;

• Press mode

• Then press 2 and ENTER key. Again press  ENTER key. it shows cell constant, again press ENTER.

• Display as

• Immerse the electrode in sample solution so as to dip electrode bulb.
• Now press enter and allow the stable value to come.
• When stable value is come go into GLP mode and press enter.
• Instrument displays as sample name.  Enter the appropriate sample name, then press enter.
• Now again instrument displays as ID No.  Enter the appropriate ID No. and then press enter.

 5.4 CALIBRATION OF pH METER

• The calibration of pH meter done with five buffer solutions.
• Reagents Required:
  • Buffer Solutions of pH 1.68, 4.01, pH 7.00, pH 9.18 and pH 12.45.
  • Distilled water
  • Frequency Of Calibration: Daily, Except holidays.
• Switch on the instrument and allow the instrument to warm up for about 15 minutes.
• Instrument displays as “LABINDIA PICO V2.22 pH/ Con meter”.
• Press the MODE key. The display will be shown as “Select Measr Mode: 1)pH  2)cond. Press ‘1’ and ENTER or MODE”
• Press the ENTER key and allow the instrument to be stabilized. The display will be shown as “Wait! Stabilizing” , ‘pH = A.BC, mv = PQR.S,*, 25°C,R2-I’.
• Then press “MEM CLEAR” it displays 1) Admin 2) User.
• Then press ‘2’ key, it displays “Enter User Password”
• Then enter the password.  And press the “ENTER” Key.
• The display show memory is clear
  • 1) Rdgs. 2) Cal. 3) All.
• Press “3” Key and then press “ENTER” Key. And then display will R1-N which means Memory is cleared.
• Press “CAL” Key and display will show “NO Data”
• Press” ENTER” Key, the display will show 1) Admin 2) User.
• Press “2” Key and the display will show” Enter Password.
• Enter the password and press ENTER Key
• The display will show “calibration Mode” 1) Stand. 2) Calib.
• Press “1”Key and press ”ENTER” Key
• Wash the electrode with distilled water. Wipe it with tissue paper.
• Take the buffer of pH 1.68 and dip the electrode in the buffer.
• Enter the pH value of Buffer. after the second decimal is stable, press the “ENTER” key.
• The display will show the pH value as 1.68 or near equal to 1.68, at near about 25°C after stabilizing. 
• After the second decimal is stable, press the ENTER key. The display will show ‘calibration over’.
• The instrument is ready for calibration with next Buffer showing display “Calibration” 1) Y. 2) N.
• Press key ‘1’and then press “ENTER”.
• Remove the electrode from the buffer of pH 1.68 and rinse thoroughly with distilled water and wipe it with tissue paper.
• Take the next Buffer of pH 4.01 and immerse the electrode in it.
• Enter the pH value of Buffer as 4.01 and press “Enter” key.
• The display will show the pH value as 4.01 or nearly equal to 4.01 at nearly about 25°C after stabilizing.
• After the second decimal is stable, press the ENTER key. The Display will show calibration is over.
• The instrument is ready for calibration with next Buffer showing display “Calibration” 1) Y. 2) N.
• Press key ‘1’and then press “ENTER”.
• Remove the electrode from the buffer of pH 4.01 and rinse thoroughly with distilled water and wipe it with tissue paper.
• Take the next Buffer of pH 7.00 and immerse the electrode in it.
• Enter the pH value of Buffer as 7.00 and press Enter key
• The display will show the pH value as 7.00 or nearly equal to 7.00 at nearly about 25°C after stabilizing.
• After the second decimal is stable, press the ENTER key. The Display will show calibration is over.
• Remove the electrode from the buffer of pH 7.00 and rinse thoroughly with distilled water and wipe it with tissue paper.
• Take the next Buffer of pH 9.18 and immerse the electrode in it.
• Enter the pH value of Buffer as 9.18 and press Enter key
• The display will show the pH value as 9.18 or nearly equal to 9.18 at nearly about 25°C after stabilizing.
• After the second decimal is stable, press the ENTER key. The Display will show calibration is over.
• Remove the electrode from the buffer of pH 9.18 and rinse thoroughly with distilled water and wipe it with tissue paper.
• Take the next Buffer of pH 12.45 and immerse the electrode in it.
• Enter the pH value of Buffer as 12.45 and press Enter key
• The display will show the pH value as 12.45 or nearly equal to 12.45 at nearly about 25°C after stabilizing.
• After the second decimal is stable, press the ENTER key. The Display will show calibration is over.
• Remove the electrode from the buffer of pH 12.45 and rinse thoroughly with distilled water and wipe it with tissue paper.
• After the last buffer calibration is over, take printout of calibration report.
• The slope will be verified in calibration report.
• The slope should not be less than 80.0% and should not be more than 120.0%.
• pH measurement
  • Press RESET
  • Rinse the electrode with distilled water and dip it in the standard buffer of pH 1.68.
  • Press the MODE key. The display will be shown as “Select Measr Mode: 1)pH  2)cond. Press ‘1’ and ENTER or MODE”
  • Again press ENTER.
  • Display reads the pH. Press ENTER key to store the reading.
  • Rinse the electrode with distilled water and dip it in the standard buffer of pH 4.01.
  • Display reads the pH. Press ENTER key to store the reading.
  • Rinse the electrode with distilled water and dip it in the standard buffer of pH 7.00.
  • Display reads the pH. Press ENTER key to store the reading.
  • Rinse the electrode with distilled water and dip it in the standard buffer of pH 9.18.
  • Display reads the pH. Press ENTER key to store the reading.
  • Rinse the electrode with distilled water and dip it in the standard buffer of pH 12.45.
  • Display reads the pH. Press ENTER key to store the reading.
  • Take printout of stored reading and verify the observed pH value of buffer solutions.
  • The pH value must not differ by more than 0.05 pH unit from the value corresponding to the buffer solution.
  • When the electrode is not in use, dip it in 3M potassium chloride solution.

5.5 CALIBRATION OF CONDUCTIVITY METER

• The calibration of conductivity meter done with 0.001 M Potassium Chloride solution.
• Reagents/Equipment Required:
  • Potassium chloride
  • Distilled Water
  • Volumetric flask 100 ml capacity
  • Beaker
  • Pipette
• Frequency of calibration: Daily, Except holidays.
• Switch on the instrument and allow the instrument to warm up for about 15 minutes.
• Now press reset, then instrument displays as “LABINDIA PICO V2.22 pH/ Con meter”
• Press the MODE key.  The display will be shown as “Select Measr. Mode: 1) pH 2) Cond.
• Press 2.  Then press ENTER key.
• The display will be shown as “Conductivity” mode press ENTER or MODE”.
• Press the ENTER key and allow the instrument to be stabilized. The display will be shown as “Enter Cell const : 0.ABC”
• Rinse the conductivity electrode and temperature sensor with distilled water.
• Rinse again with 0.001 M potassium chloride solution and immerse in the same solution having temperature of 25°C.
• Enter the cell constant (i.e., 0.1 for electrode LC 1 and 1.0 for electrode LC 10 ) and press the ENTER key
• The display will be shown as “Calibrate  ”1) Y     2) N
• Press 1 for selecting Y and then ENTER key.
• Display shows “1) Admin  2) User.
• Then press ‘2’ key ,it displays “Enter password”, Enter the password.
• Press the ENTER key and then enter the solution conductance (147).
• Press ENTER key. The display will be shown as “Conductance 1) µS 2) mS”.
• Press 1 for selecting µS and then ENTER key.
• Enter the cell coefficient (1.96) (which is written on electrode)
• Press ENTER key, the display will be shown as “ATC at: 1 1)25°C 2) 20°C”.
• Press 1 for selecting temperature of 25°C, The display will be shown as “Select Tempo mode: 1 1) Auto 2) manual”.
• Press 1 for selecting auto and allow the instrument to stabilize.
• Allow to attain the conductance 147.
• When instrument will attain the value 147 ± 2. Press ENTER key.
• Conductivity calibration report will be printed out calibration is over.

 6.0 ABBREVIATIONS:

Abbreviation	Expanded form
No.	Number
Dept	Department
M	Molar
Calib	Calibration
%	Percentage
Cond	Conductivity

7.0 ANNEXURES:

Annex. No.	Title
01	Calibration Record of pH Meter
02	Calibration Record of Conductivity Meter
03	Label For Potassium Chloride Solution

8.0 SOP REFERENCES

• Instrument Manual

END OF THE SOP

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ANNEXURES :

Annex. No. 01 Calibration Record of pH Meter

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Annex. No. 02 Calibration Record of Conductivity Meter

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Annex. No. 03 Label For Potassium Chloride Solution

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