dosage forms.

2. Scope

This procedure applies to the Analytical Method Development (AMD) department and includes acid-base titrations, redox titrations, complexometric titrations, non-aqueous titrations, and gravimetric precipitation techniques.

3. Responsibilities

• Analytical Chemist: Prepares reagents, performs assay trials, and documents results.
• Reviewer: Verifies calculations and precision of results.
• QA Representative: Ensures compliance with regulatory and GMP documentation requirements.
• Head – AMD: Reviews and approves finalized method for routine use.

4. Accountability

The Head of Analytical Method Development is accountable for ensuring all classical assay methods are validated, scientifically justified, and suitable for routine QC application or regulatory submission.

5. Procedure

5.1 Selection of Assay Technique

1. Review monographs (IP, USP, BP) and literature for available classical assay methods.
2. Select based on:
   • Analyte functionality (acid, base, metal ion)
   • Stability in aqueous/non-aqueous medium
   • Availability of primary standards and indicators
3. Record justification in Annexure-1: Technique Selection Record.

5.2 Preparation of Reagents and Solutions

1. Prepare volumetric solutions (e.g., NaOH, HCl, KMnO₄, EDTA) using analytical-grade reagents.
2. Standardize all titrants using certified primary standards:
   • Sodium carbonate for HCl
   • Oxalic acid for KMnO₄
   • Zinc or calcium carbonate for EDTA
3. Document normality and standardization factors in Annexure-2: Volumetric Solution Log.

5.3 Sample Preparation

1. Accurately weigh the test substance as per assay specification (typically 500–1000 mg).
2. Dissolve in suitable solvent (water, ethanol, glacial acetic acid, etc.).
3. Filter or sonicate if necessary to obtain a clear solution.
4. Document solution preparation in Annexure-3: Sample Prep Log.

5.4 Performing the Assay

1. Choose appropriate titration technique:
   • Acid-base titration: Phenolphthalein or methyl orange indicators
   • Redox titration: KMnO₄, I₂, or ceric ammonium nitrate
   • Complexometric titration: EDTA with Eriochrome Black T or Murexide
   • Non-aqueous titration: Perchloric acid in glacial acetic acid medium
2. Conduct triplicate titrations and calculate percentage assay using formula:

   % Assay = (V × N × Eq. Wt × 100) / (W × 1000)

   Where:

   • V = Volume of titrant (mL)
   • N = Normality
   • Eq. Wt = Equivalent weight of analyte
   • W = Sample weight (mg)
3. Record titration data in Annexure-4: Assay Calculation Sheet.

5.5 Method Optimization

1. Evaluate:
   • Endpoint detection using visual vs. potentiometric titration
   • Impact of temperature, solvent volume, and mixing
   • Stability of analyte in chosen medium
2. Document optimization findings in Annexure-5: Optimization Record.

5.6 Method Validation

1. Specificity: Use placebo or excipients to confirm no interference at endpoint.
2. Precision:
   • Repeatability: RSD ≤ 1.0% for 6 replicates
   • Intermediate Precision: Different analyst or day
3. Accuracy: Spike placebo with known API quantity at 80%, 100%, and 120% levels. Recovery should be 98–102%.
4. Linearity: Vary sample quantity (50–150%) and plot titrant volume vs. analyte weight.
5. Robustness: Change indicators, solvent volume, or titration speed and monitor effect.
6. Document validation results in Annexure-6: Validation Summary Report.

6. Abbreviations

• SOP: Standard Operating Procedure
• RSD: Relative Standard Deviation
• API: Active Pharmaceutical Ingredient
• Eq. Wt: Equivalent Weight

7. Documents

1. Technique Selection Record – Annexure-1
2. Volumetric Solution Log – Annexure-2
3. Sample Prep Log – Annexure-3
4. Assay Calculation Sheet – Annexure-4
5. Optimization Record – Annexure-5
6. Validation Summary Report – Annexure-6

8. References

• USP General Chapter <541> – Titrimetry
• IP General Notices – Classical Assays
• ICH Q2(R1) – Validation of Analytical Procedures
• Ph. Eur. 2.2.20 – Potentiometric Titrations

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Technique Selection Record

Analyte	Recommended Technique	Justification	Analyst
Aspirin	Back titration with NaOH	Weak acid, poor water solubility	Rajesh Kumar

Annexure-2: Volumetric Solution Log

Solution	Normality	Standardized Against	Prepared By
0.1 N NaOH	0.1002	Potassium hydrogen phthalate	Sunita Reddy

Annexure-3: Sample Prep Log

Sample	Weight (mg)	Solvent Used	Dilution Volume	Prepared By
Paracetamol Tablet	500	Ethanol:Water (1:1)	100 mL	Ajay Mehra

Annexure-4: Assay Calculation Sheet

Trial	Volume (mL)	% Assay	Analyst
1	22.45	99.2%	Rajesh Kumar

Annexure-5: Optimization Record

Parameter Changed	Observation	Outcome
Indicator changed to phenol red	Poor color contrast	Rejected
Solvent volume increased	Improved precision	Accepted

Annexure-6: Validation Summary Report

Parameter	Criteria	Result	Status
Accuracy	98–102%	99.6%	Pass
Precision	RSD ≤ 1%	0.84%	Pass
Linearity	R² ≥ 0.999	0.9993	Pass

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
04/05/2025	2.0	Integrated gravimetric options and added validation annexures	Annual SOP Review