in line with ICH stability and stress testing guidelines.

2. Scope

This SOP applies to the Analytical Method Development (AMD) department and is relevant for assessing thermal degradation of active pharmaceutical ingredients (APIs), intermediates, and excipients under accelerated temperature conditions using GC-based techniques.

3. Responsibilities

• Analytical Chemist: Conducts thermal exposure, GC analysis, and documentation of degradation profiles.
• Reviewer: Evaluates chromatograms, peak identification, and system suitability results.
• QA Officer: Verifies protocol adherence, calibration, and log entries.
• Head – AMD: Approves thermal stress reports and final SOP implementation.

4. Accountability

The Head of Analytical Method Development is accountable for ensuring that thermal stability testing using GC is performed, reviewed, and documented in compliance with regulatory requirements and method validation standards.

5. Procedure

5.1 Selection of Compounds for Thermal Stability Testing

1. Identify thermolabile compounds based on chemical structure and known decomposition behavior.
2. Prioritize compounds with functional groups like esters, amides, or peroxides.
3. List all compounds under evaluation in Annexure-1: Test Compound Register.

5.2 Instrument Setup and Method Parameters

1. Instrument: Gas Chromatograph with Flame Ionization Detector (FID).
2. Column: DB-5 (30 m × 0.25 mm ID × 0.25 µm film thickness).
3. Oven Temperature Program:
   • Initial: 40°C (1 min)
   • Ramp: 10°C/min to 300°C
   • Hold: 5 min
4. Injector Temp: 250°C | Detector Temp: 280°C
5. Carrier Gas: Helium at 1.0 mL/min (constant flow)
6. Record parameters in Annexure-2: GC Method Setup Log.

5.3 Sample Preparation

1. Weigh 100 mg of test compound into a clean, dry glass vial.
2. Add diluent (e.g., DMSO, DMF, or acetone) to achieve 1 mg/mL concentration.
3. Mix thoroughly using vortex for 30 seconds.
4. Prepare control sample (no heat exposure) alongside.
5. Record details in Annexure-3: Sample Preparation Log.

5.4 Thermal Exposure Procedure

1. Expose test samples to controlled temperature chambers or oil baths at:
   • 60°C, 80°C, 100°C, and 120°C
2. Maintain exposure durations: 1 hr, 3 hrs, and 6 hrs for each temperature level.
3. Allow samples to cool and analyze immediately or store at 2–8°C until injection.
4. Log exposure conditions in Annexure-4: Thermal Stress Exposure Sheet.

5.5 GC Analysis of Degraded Samples

1. Inject blank, standard, and thermally stressed samples in sequence.
2. Chromatographic run time: ~30 minutes per sample.
3. Evaluate:
   • Retention time shift
   • Peak purity and symmetry
   • Formation of unknown degradation peaks
4. Overlay chromatograms for comparison and assess degradation profile.
5. Document in Annexure-5: Degradation Profile Report.

5.6 Interpretation of Results

1. Determine degradation extent based on decrease in API peak area vs. control.
2. Degradation (%) = [(Area_control − Area_stressed) / Area_control] × 100
3. Note appearance of new peaks (degradants) and record their retention time and estimated area.
4. Summarize thermal stability conclusions in Annexure-6: Summary Interpretation Log.

5.7 System Suitability

1. Inject standard in five replicates.
2. Acceptance Criteria:
   • %RSD of area ≤ 2.0%
   • Resolution between main peak and nearest degradant ≥ 1.5
3. Log results in Annexure-7: System Suitability Report.

6. Abbreviations

• API: Active Pharmaceutical Ingredient
• FID: Flame Ionization Detector
• GC: Gas Chromatography
• RT: Retention Time
• RSD: Relative Standard Deviation
• SOP: Standard Operating Procedure

7. Documents

1. Test Compound Register – Annexure-1
2. GC Method Setup Log – Annexure-2
3. Sample Preparation Log – Annexure-3
4. Thermal Stress Exposure Sheet – Annexure-4
5. Degradation Profile Report – Annexure-5
6. Summary Interpretation Log – Annexure-6
7. System Suitability Report – Annexure-7

8. References

• ICH Q1A(R2) – Stability Testing of New Drug Substances and Products
• ICH Q2(R1) – Validation of Analytical Procedures
• USP <621> – Chromatography
• FDA Guidance on Forced Degradation Studies

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Test Compound Register

Compound Name	Batch No.	Structure Class	Comments
API-207	B23-077	Amide	Known to degrade above 100°C

Annexure-2: GC Method Setup Log

Column	Oven Program	Carrier Gas	Detector
DB-5	40–300°C @ 10°C/min	Helium	FID

Annexure-3: Sample Preparation Log

Sample ID	Weight (mg)	Diluent	Final Volume (mL)
TS-001	100	DMF	100

Annexure-4: Thermal Stress Exposure Sheet

Temp (°C)	Duration	Observation	Analyst
100	3 hrs	Yellowing	Sunita Reddy

Annexure-5: Degradation Profile Report

Sample	Main Peak Area	% Degradation	No. of New Peaks
TS-001 @ 100°C	89456	10.2%	2

Annexure-6: Summary Interpretation Log

Sample	Temperature	Result	Conclusion
TS-001	100°C	Degraded	Thermally unstable at 100°C

Annexure-7: System Suitability Report

Injection No.	RT (min)	Area	%RSD
1	5.24	90213	1.5%
2	5.25	89567
3	5.26	90412
4	5.24	89987
5	5.25	90321

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
04/05/2025	2.0	Expanded to include stress duration tracking and interpretation annexures	Annual Review