Operation and Calibration of Potentiometric Titrator
This Document describes (Standard Operating procedure) Sop for Operation and Calibration of Potentiometric Titrator
Sop for Operation, cleaning and Calibration of Potentiometric Titrator.
I. Purpose & Scope:
- The Purpose of this SOP is to lay down the procedure to lay down a procedure for Operation, Cleaning & Calibration of Potentiometric Titrator.
- This procedure is applicable for Operation, cleaning & Calibration of Potentiometric Titrator used in Quality Control Department
II. Responsibilities:
- All Quality Control personnel shall be responsible to follow and implement this SOP.
III : Introduction and Procedural Part :
General Cleaning of Potentiometric Titrator :
- Clean the instrument with a clean dry cloth every day. Occasionally wet cloth dipped in dilute soap solution may be used.
- Precautions has to be taken to clean the instrument immediately with dry cloth to remove the moisture.
Basic Operations of Potentiometric Titrator :
- Switch on the main power switch and switch on the power switch provided on the rear side of the instrument and connect the electrode and printer to the instrument.
Connecting and Removing Burette Assembly :
- Press Fill key before connecting and removing burette assembly. Check valve pin position, it should be straight.
- Adjust piston before connecting burette assembly. Place assembly on mechanism and push towards front side gently. Press ‘FILL’ key and check piston up and down movements.
- If it is ok then assembly is connected properly.
Rinsing and Filling Burette:
- After connecting the burette assembly, rinse the burette by the titrant as follows.
- Keep the reagent bottle on the burette assembly and Put the filling tube in solution and dispense tube in waste beaker. (To avoid the wastage of solution keep the tip of the dispense tube in reagent bottle.)
- Select rinsing function through ‘Aux Function’ key and press ‘GO’ key.
- Same way filling of the burette can be done or pressing ‘FILL’ key can fill burette. After filling the burette instrument is ready for titration.
Performing the Potentiometric Titration:
- If the program of particular titration is already feed to the instrument, then recall the program by pressing ‘User Method Key’ and enter the variables in ‘Formula’ and ‘Sample Data’ key.
- For the new sample make the program as follows:
- Press the ‘MODE’ key and select the required mode: Sample Mode / Normality Mode / Blank Mode. Press enter key after selecting the required mode.
- Press the ‘METHOD key’ and select the required method:
- SVD : Step volume dosing
- Press enter key after selecting the required method on the screen of Potentiometric Titrator.
Parameter setting of the method:
- Press the method key and then parameter key to set the parameters for that particular method. Set the parameters as per the requirement and press enter key after giving each parameter.
- Press formula key. Display will be: Formula No
- Give the formula No.
- For Blank mode : No Formula
- Normality mode : Formula No. 01-03
- Sample mode : Formula No. 01-10
- Press enter key, first parameter of the formula will display. Give the valve of that parameter and press enter key next parameter will display. Repeat the same procedure to enter the parameters of the formula.
- Press ‘Sample Data’ key to enter the sample details. First parameter of the sample details will display, give the parameter and press enter key, next parameter will display. Repeat the same procedure to enter all the parameters of the sample data.
- Note: To type the alphabets press shift key and then alphabets key, after typing the alphabets again press shift key and then press enter key. 3, 4Keys are used to move the cursor forwards and backwards.
- Press ‘Aux. Function.’ Key to enter the auxiliary parameters of the titration. Press enter key after giving each parameter. After preparing the program for the particular user method it is stored in memory as follows : ( e.g. To store the user method No. 1 )
- Press ‘User method’ key (it is rolling key) till display of ‘Delete No. ??’ enter the number of user method (e.g. 01) and then press enter key again press the user method key till display of ‘Store No. ??’ appears. Enter the no. of user method to be stored (e.g. 01) and then press enter. The user method gets stored in memory.
- Recall method using ‘User Method’ key and Enter variable in formula and sample data key.
- After entering all the variables, keep titration vessel on titration stand. Start stirrer by pressing stirrer speed selecting keys (3,4). (Air Bubble should be avoided)
- Check mV using monitor key. If mV are stable press ‘method key’ and then ‘GO key’ and Titration gets started.
- After titration is completed press enter key to select options (PC/PRN/LCD 0/1/2) press 1 to select printer.
- Press ‘Report key’ (Rolling key) to select report type (result report, parameter report, document report, graphics). ‘Press enter key’ printing will start.
Safety and precautions while operation of potentiometric titrator:
- Clean the electrode and store it as per electrode requirement. Remove the solutions from burette and tubing after completion of titration.
- Always follows procedure given for connecting and removing burette assembly if not it may break the burette.
Calibration of Potentiometric Titrator :
Calibration Frequency:
Once in three months and after each maintenance job.
Calibration of burette Dosing:
- Check all the connection and switch on the instrument.
- Set the drift value of the dosing at minimum through the knob given in front of the instrument.
- Start the dosing by pressing the Dose Button on the front panel of the instrument for 10 ml and 20 ml separately. Collect the dispensed volume in a empty beaker. Determine the dispensed volume in ml as follows.
- Dispensed volume (ml) = (Wt. of beaker + water) – Weight of beaker)
Determination of Density of water:
Take a 10 ml water by using pipette (grade A) and weigh on analytical balance. Determine the density of water by using following formula.
Weight of water (gm)
Density of water (d) = —————————– X 0.997 Water taken (ml)
Calculate the relative error % as follows :
Volume on Display (ml) – Dispensed Volume (ml)
= ——————————————————————– X 100
Volume on Display (ml)
The relative error should not be more than + 0.5%.
- Record the observation in the calibration record as per the Annexure-I.
Calibration of pH on potentiometric titrator:
- Check all the connection and switch on the instrument.
- Press ‘monitor’ key. Display will show ‘Monitor/Enter. Now to perform calibration press ‘Enter’ key. Display will show ‘Calibration? YES=GO No.=ENTER.
- Then press ‘Go’ key display will show ‘Temp A/M/1/0’. If automatic Temperature indication with temperature sensor (RTD) is required then press ‘1’ otherwise is selected then display will show Temp 25.00 C. Change/Clear/Enter
- Enter temperature value manually then press ‘Enter’
- Display will show ‘Standard 07.00 pH electrode in 7.00 pH and press Enter. Then display will shows ‘pH1 04.00, dip the electrode in the selected buffer and press Enter. The Titrator checks for stable pH value for few seconds. If proper stability not observed, message ‘Buffer not proper’ will appear. Change the buffer not proper’ will appear. Change the buffer or Electrode if defective. If the readings are stable, the instrument will go through calibration process for the first buffer and will come to the next stage and will display “pH 09.20. Carry out the same procedure as above for second buffer e.g. 9.20.
- After the above step the titrator will complete the calibration and a message “Calib Report?”
- “YES=GO/NO=Enter will appear
- Press “Go” for printed report. Now report will shows exact value of buffer calibrated along with temperature, asymmetric voltage and slope.
- Electrode sensitivity shall be performed by outside calibration agency on yearly basis.
- If any discrepancy observed during operating the instrument report to QC Manager & notify the defect to Maintenance Manager to rectify the defect. Affix ‘Under Maintenance Label’ on the instrument.
IV: Annexure :
Annexure I : Instrument/Equipment Calibration Record – Potentiometric Titrator.
Annexure -I
Instrument/Equipment Calibration Record – Potentiometric Titrator
| Name of Instrument : Potentiometric titrator | Date of Calibration : |
| Make : | Model : |
| Department: Quality Control | Instrument ID No : |
| Frequency : | |
Calibration of burette Dosing:
- A) Cleanliness of the Potentiometric Titrator :
Observation: Clean / Not Clean Date:
Corrective action in the case of non-compliance: Sign:
- Any other maintenance:
Observation: Required / Not required Date:
Corrective action in case of non-compliance: Sign:
- B) Burette calibration
Weight of water (gm)
Density of water (d) = —————————– X 0.997 = ————–X 0.997 = ________ gm/ml
Water taken (ml)
| Burette No. | Dosing Volume | Volume on display (X) | Tare Weight of beaker in gm. (a) | Weight of beaker with water in gm. (b) | Dispensed Volume in ml (Y)
_(b-a)_ 0.997 |
Relative Error
(NMT+ 0.5 %) X – Y ———-x100 X |
| 10 ml | ||||||
| 20 ml | ||||||
| 10 ml | ||||||
| 20 ml |
| Name of Instrument : Potentiometer | Date of Calibration : |
| Make : | Model : |
| Department: Quality Control | Instrument ID No : |
| Frequency : | |
- II) Calibration of pH:
| Sr. No. | Standard pH | Observed pH |
| 1 | ||
| 2 | ||
| 3 |
Remark: The instrument i.e. potentiometric titrator is calibrated and complies / does not comply with the acceptance criteria.
Calibrated By: Checked By: Head QC
Date : Date : Date :
