(FTIR) Spectroscopy with Attenuated Total Reflectance (ATR) technique.

2. Scope

This SOP applies to Analytical Method Development (AMD) and Quality Control (QC) teams responsible for identifying excipients present in cream formulations using FTIR spectroscopy during formulation development and raw material authentication.

3. Responsibilities

• Analytical Scientist: Prepares samples, operates FTIR instrument, interprets spectra.
• QC Analyst: Assists with sample handling and record maintenance.
• QA Executive: Verifies spectral matches and approves documentation.

4. Accountability

The Head of Analytical Method Development is accountable for the proper validation of the FTIR-based identification method and its application in routine and investigational analysis.

5. Procedure

5.1 Instrumentation

1. FTIR Spectrophotometer equipped with ATR (e.g., ZnSe, diamond crystal)
2. Resolution: 4 cm^-1
3. Scan range: 4000–650 cm^-1

5.2 Sample Preparation

1. Apply a thin layer (~0.05 g) of cream or isolate onto the ATR crystal.
2. Ensure even contact between sample and crystal; avoid air gaps.
3. Clean crystal before and after each measurement using alcohol and lint-free tissue.

5.3 Reference Standards

1. Prepare FTIR spectra of individual cream base components such as:
   • Stearyl alcohol
   • Cetostearyl alcohol
   • White soft paraffin
   • Liquid paraffin
   • Polysorbate 60
   • Propylene glycol
2. Store spectral library with spectral ID code and date (Annexure-2).

5.4 Measurement

1. Run background scan without sample.
2. Place sample and acquire 32 scans per spectrum.
3. Compare sample spectrum with reference using software-based match algorithms (e.g., % correlation).

5.5 Interpretation and Reporting

1. Match spectra with ≥ 90% correlation to reference library spectrum for identification confirmation.
2. Check for presence of functional groups corresponding to:
   • O-H stretch (alcohols, ~3300 cm^-1)
   • C-H stretch (alkanes, ~2850–2950 cm^-1)
   • C=O stretch (esters, ~1730 cm^-1)
3. Document and attach spectra to Annexure-1.

5.6 Method Validation Parameters

1. Specificity: Spectra must distinguish between structurally similar excipients (e.g., paraffin grades).
2. Repeatability: Triplicate spectra must yield ≥ 95% similarity RSD ≤ 2%
3. Ruggedness: Confirm reproducibility across analysts and instruments.

6. Abbreviations

• FTIR: Fourier Transform Infrared
• ATR: Attenuated Total Reflectance
• QA: Quality Assurance
• AMD: Analytical Method Development

7. Documents

1. Sample Spectral Record – Annexure-1
2. Spectral Library and Reference ID Table – Annexure-2
3. Validation Summary Report – Annexure-3

8. References

• USP <197K>: Infrared Spectroscopy
• Ph. Eur. 2.2.24: Identification by Infrared Spectrophotometry
• ICH Q2(R1): Validation of Analytical Procedures

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name	Priya Nair	Manoj Joshi	Sunita Reddy
Designation	FTIR Analyst	QA Reviewer	Head – AMD
Department	Analytical Method Development	QA	Analytical Method Development

11. Annexures

Annexure-1: Sample Spectral Record

Sample ID	Spectral Match (%)	Component Identified	Status
CRM-263-01	95.4%	Cetostearyl Alcohol	Pass

Annexure-2: Spectral Library and Reference ID Table

Component	Spectrum ID	Date Recorded	Analyst
White Soft Paraffin	WSP-01	10/04/2025	Priya Nair
Polysorbate 60	POL60-02	12/04/2025	Priya Nair

Annexure-3: Validation Summary Report

The FTIR method for identification of cream base excipients was validated using five components. Results showed ≥ 95% spectral similarity across triplicates with RSD ≤ 1.8%. The method is suitable for rapid qualitative identification of excipients in semi-solid formulations.

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
21/05/2025	2.0	Added ATR specifics and spectral match acceptance criteria	Annual Review	Sunita Reddy
01/05/2022	1.0	Initial SOP Release	New SOP	QA Head