Learn how to calibrate the Automatic Potentiometric Titrator using Disodium tartrate as standard with step-by-step procedures for factor repeatability, burette calibration, acceptance criteria, and precautions.
Calibration of analytical instruments is essential in pharmaceutical laboratories to ensure accurate titration results. This guide explains how to calibrate the Automatic Potentiometric Titrator using Disodium tartrate as standard, including repeatability checks and burette calibration procedures.
🎯 Objective
To establish a standard procedure to:
- Calibrate the Automatic Potentiometric Titrator using Disodium tartrate as standard
- Verify repeatability of factor determination
- Perform accurate burette calibration
⚙️ Initial Setup
- Turn ON the instrument and printer.
- Ensure the system is clean and ready for operation.
🔁 A. Repeatability of Factor Determination
🧪 Procedure
- Go to Titer Mode.
- Use Disodium tartrate as standard.
- Carefully weigh and transfer the sample to avoid variation.
- Enter the sample weight into the system.
- Determine the factor (titer value).
- Record five readings.
📊 Calculations
- Calculate the average factor.
- Determine % Relative Standard Deviation (%RSD).
✅ Acceptance Criteria
- %RSD should be not more than 0.5%
🧪 B. Calibration of Burette
⚙️ Preparation
- Clean the ICB (Interchangeable Burette) thoroughly.
- Fill the reservoir with distilled water.
- Fill the burette properly.
📏 Step-by-Step Calibration
🔹 1. Calibration at 0.10 ml
- Set eject volume to 0.10 ml in AUX functions.
- Press eject and collect liquid in a pre-weighed beaker.
- Weigh and calculate volume:
Volume (ml)=0.99602Weight (g)
✅ Acceptance Criteria
- 0.0990 ml to 0.1010 ml
🔹 2. Calibration at 1.0 ml
- Set eject volume to 1.0 ml.
✅ Acceptance Criteria
- 0.99 ml to 1.01 ml
🔹 3. Calibration at 10.0 ml
- Set eject volume to 10.0 ml.
✅ Acceptance Criteria
- 9.98 ml to 10.02 ml
🔹 4. Calibration at 20.0 ml
- Set eject volume to 20.0 ml.
✅ Acceptance Criteria
- 19.97 ml to 20.03 ml
⚠️ Precautions
- Avoid errors during weighing and transfer of standard.
- Use clean, dry, and pre-weighed beakers.
- Ensure no air bubbles in the burette.
- Clean the ICB with acetone after calibration.
🔄 Calibration Frequency
- Perform calibration once every three months
📄 Acceptance Summary
✔ Repeatability
- %RSD ≤ 0.5%
✔ Burette Calibration Limits
| Volume (ml) | Acceptable Range (ml) |
|---|---|
| 0.1 | 0.0990 – 0.1010 |
| 1.0 | 0.99 – 1.01 |
| 10.0 | 9.98 – 10.02 |
| 20.0 | 19.97 – 20.03 |
🔧 Conclusion
- Calibration Complies / Does Not Comply as per SOP.
- Record results and determine next calibration due date.
📚 Reference
- Indian Pharmacopoeia (IP)
- User Manual for Automatic Potentiometric Titrator
❓ Frequently Asked Questions (FAQs)
1. Why is disodium tartrate used as a standard?
It is a stable reference compound for accurate factor determination.
2. What is the purpose of titrator calibration?
To ensure accurate titration results and reliable factor calculations.
3. What is %RSD in calibration?
It measures the precision of repeated readings.
4. What is the acceptable %RSD limit?
It should be not more than 0.5%.
5. Why is burette calibration important?
It ensures the correct volume is dispensed during titration.
6. Why is density correction (0.99602) used?
It corrects water weight to volume at standard temperature.
7. What happens if calibration fails?
The instrument should not be used until recalibrated.
8. How often should calibration be performed?
Every three months or as per SOP.
9. Why should the burette be cleaned with acetone?
To remove moisture and ensure accurate volume delivery.
10. What precautions should be taken during calibration?
Avoid weighing errors, ensure clean equipment, and prevent air bubbles.