Auto Titrator – Operation and Calibration SOP

Standard Operating Procedure (SO) for Operation and Calibration of Auto Titrator (Potentiometer) for its utility in carrying out different types of Titration

SOP for Auto Titrator (Potentiometer)

1.0   PURPOSE:

    • The purpose of this Standard Operating Procedure (SOP) is to describe the procedure for the Operation and Calibration of the Auto Titrator for its utility in carrying out different types of Titration.

2.0   SCOPE:

    • This SOP is applicable to the following Auto Titrator at the Quality control department.

3.0   REFERENCES:

    • Operation Manual of Auto Titrator supplied by the manufacturer.
    • SOP for Handling Out of Calibration (OOC).

4.0   RESPONSIBILITY – SOP FOR AUTO TITRATOR:

    • QC-Officer :

    • To perform and check the calibration and maintain the documents of laboratory instruments (Auto Titrator ) as per SOP.Auto Titrator
    • Operate the Auto Titrator as per the SOP.
    • To calibrate the Auto Titrator as per SOP.
    • To maintain the logbook, calibration record, history card.
    • Quality Control Head or Designee :

    • To give training to all the concerned persons before the implementation of the SOP.
    • Ensure that the calibration and documentation of the instruments as per SOP.
    • To review the SOP.
    • Quality Assurance :

    • To ensure the implementation of the system as per SOP.

5.0   PROCEDURE- SOP FOR AUTO TITRATOR:

    • General Procedure for Handling of Auto Titrator:

    • Follow the SOP on Instrument / Equipment usage logbook, for the entry of usage of the instrument.
    • In case of any maintenance of the instrument, follow SOP of Maintenance of Laboratory Instrument.
    • In case of noticing any calibration results, not within the specified limit, follow the SOP of Handling Out of Calibration.
    • Precautions during Handling of Auto Titrator:

    • Wash the electrode thoroughly after completion of the analysis and store it in a specified solution.
    • Set the Titration vessel for firm seating in the titration head at the time of analysis.
    • Operational Procedure of Auto Titrator:

    • Check the cleanliness of the instrument.
    • Check the calibration status of the Auto Titrator.
    • Clarity of the titrant to be check.
    • Switch ON the instrument.
    • The instrument always performs a self-test before the display of the Titrator name appears.
    • Ensure that the computer is in standby mode.
    • Click on the Auto Titrator Software icon on the desktop.
    • The Auto Titrator software initializes and the next screen appears on the desktop.
    • After initialization, the following screen appears.
    • Right-click on the Instrument Code button and select an open view.
    • Operate the Instrument as per Operation SOP for Auto Titrator (Make and Model Specific)

6.0   Calibration Procedure of Auto Titrator:

    • Calibration parameters are as given below.
    • Electrode calibration check.
    • Burette calibration check.
    • Calibration frequency of Auto Titrator: Quarterly ± 7 days or after any maintenance.
    • A calibration check of Auto Titrator shall be carried out after the following maintenance.
Name of the module Type of maintenance Calibration parameter required
Change in Burette Replacement Burette calibration check
Change in Electrode Replacement Electrode calibration check
    • Calibration requirement for other maintenance should be derived case by case basis and as per instrument manual.
    • Electrode calibration check :

    • The electrode calibration check shall be carried out as per the supplier’s recommendations in the instrument manual.
    • The electrode calibration check for some of the commonly used electrodes is as given below.
    • Following Auto Titrator Electrode calibration check for the electrodes DG113, DG111, and DG115 (Make: Mettler Toledo):
      • Electrode For pH measurement and titrations in non-aqueous media. (i.e. DG 113)
      • For pH measurement and acid/base titration in aqueous media (i.e. DG 111)
      • For pH measurements and acid/base titrations in aqueous media. Suitable for use in polar solvents, e.g. titration with perchloric acid in acetic acid or with sodium methylate in methanol and other media with low ion concentration. (i.e. DG 115)
    • Adjust the temperature of the buffer solution of pH 4.0 to 25°C ± 2°C.
    • Select the appropriate method for the calibration of the electrode.
    • Transfer about 50 ml of buffer solution of pH 4.0 into the titration cup and fix it with the apparatus.
    • Immerse the electrode into the buffer solution of pH 4.0.
    • Follow the same procedure by using the buffer solution of pH 7.0. and 9.2.
    • The slope value so obtained should be within -55 to -65.
    • Electrode calibration check for the electrode DM141 (Mettler Toledo):

      • DM141: Combined silver ring electrode for precipitation titrations with the change of the pH value
    • Take about 50 ml of 0.1 mol/L solution of silver nitrate in the titration vessel and fix it with the apparatus.
    • Maintain the temperature of calibrating solutions at 25°C ± 2°C.
    • Check the electrode potential. It should be within the range of 250 to 350 Millivolts.
    • Burette calibration check:

    • Burette calibration shall be carried out by 5 ml, 10ml, and 15 ml dispensing in triplicate for 10 ml Burette and 10 ml, 20ml, and 30 ml dispensing in triplicate for 20 ml burette.
    • Similarly for other capacity Burette calibration shall be done 50% to 150 % of Burette Capacity.
    • Take 1000 ml of water in the bottle and maintain the temperature of water at 25°C± 1°C during the calibration.

                 Note: Burette and the dispensing tube should be free from the air bubble at the time of analysis.

    • Keep the dispensing tube outlet in a previously weighed beaker (W1).
    • Dispense the water in a beaker and remove the air bubble and weigh it (W2)
    • Follow the above procedure by selecting the volume 5ml, 10 ml, and 15 ml for 10 ml Burette.
    • Perform the calibration in triplicate.
    • In case of failure of calibration follow the Handling out of Calibration procedure for Laboratory Instruments.
    • By using the calculation formula given in Attachment-1 find out the Burette volume.

Note:

    • A burette calibration check shall be derived based upon the same analogy for the burettes of other volumes.
    • If the expected burette reading in any of the analysis is less than the calibration range then the Burette calibration check shall be designed in such a way that it covers the entire operating range.
    • Observed burette volume in ml (Individual and Mean) should fall within the limit – NMT ± 0.2%.
    • Weight per ml of water at 25°C is 0.99602, at 24°C is 0.99631 and at 26°C is 0.99562.
    • If the room temperature is above 24.5°C but below 25.5°C then the factor of 0.99602 shall be applied.
    • If the temperature is between 24.5°to24.0°C then the factor of 0.99631 shall be applied and if the temperature is between 25.5°- 26.0°C then the factor of 0.99562 shall be applied.

7.0   Calibration Template / Format for Auto Titrator :

    • Annexure-1: Calibration Template of Auto Titrator.
A) Electrode calibration check for the electrodes DG111, DG113, and DG115.
Instrument Name: Auto Titrator
Instrument No   Make/Model
Location   Calibration frequency Quarterly ±7 days
Calibrated on   Next calibration due on
    • Code No. of Buffer pH 4.0 ____________
    • Buffer pH 7.0 ____________________ 
    • Buffer pH 9.2 ____________________ 
Type of Sensor Standard Buffer value Temperature 25°C±2°C Observed value of slope Limit
DG 111 4.0 Between -55 to -65
7.0
9.2
DG 113 4.0 Between -55 to -65
7.0
9.2
DG 115 4.0 Between -55 to -65
7.0
9.2

 

B)          Electrode calibration check for the electrodes DM141

Instrument Name : Auto Titrator
Instrument No   Make/Model
Location   Calibration frequency Quarterly ±7 days
Calibrated on   Next calibration due on

 

Reagent Batch No Make/Grade Use Before
Silver Nitrate
Water NA

 

Preparation of 0.1M Silver Nitrate :

    • Weight and transfer accurately about 17.5 gm of Silver Nitrate in a 1000 ml volumetric flask.
    • Dissolve in 700 ml of water.
    • Dilute up to the mark with water.
Type of Sensor Temperature 25°C±2°C Observed value Limit
DM141 Between 250 to 350

 

C)          10 ml Burette calibration check log

Instrument Name : Auto Titrator
Instrument No   Make/Model
Location   Calibration frequency Quarterly ±7 days
Calibrated on   Next calibration due on

 

Instrument used Code No. Valid up to
Balance
Thermometer

 

Standard volume in ml Temperature 25°C±1°C Observed Burette volume in ml Limit: Not more than ±0.2%
Individual Mean
5 ml 4.990 ml to 5.010 ml
10 ml 9.980 ml to 10.020 ml
15 ml 14.970 ml to 15.030 ml

 

Note :  Weight per ml of water at 250C is 0.99602, at 240C is 0.99631 and at 260C is 0.99562. If the room temperature is above 24.50C but below 25.50C then the factor of 0.99602 shall be applied and if the temperature is between 24.50C to 24.00C then the factor of 0.99631 shall be applied and if the temperature is between 25.50C – 26.00C then the factor of 0.99562 shall be applied.

 For 5 ml Dispensing (Triplicate Readings)

5 ml Dispensing Set 1 S-2 S- 3
Wt. of the beaker    
Weight of  water+ beaker    
Wt. of water    

 

    • Set 1
    • Calculation      :             Wt of water       r       =  ————————    =                              ml  

                                                         Weight/ ml of water    

    • S-2
    • Calculation      :             Wt of water       r       =  ————————    =                              ml  

                                                       Weight/ ml of water  

    • S-3
    • Calculation      :             Wt of water       r       =  ————————    =                              ml  

                                                        Weight/ ml of water    

 

Mean Volume (ml)  =  Set-1 (Dispense Vol.) + Set-2 (Dispense Vol.) + Set-3 (Dispense Vol.)

                                                                                              3

 

                                =              ml +            ml  +              ml         =                       ml

                                                                  3

For 10 ml Dispensing (Triplicate Readings)

10 ml Dispensing S 1 S-2 S- 3
Wt. of the beaker    
Weight of  water+ beaker    
Wt. of water    

Perform All 3 sets for 10 ml and 15 ml (as per 5 ml).

 

 

pharmabeginers

Janki Singh is experienced in Pharmaceuticals, author and founder of Pharma Beginners, an ultimate pharmaceutical blogging platform. Email: [email protected]

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