consistency.

2. Scope

This SOP applies to tablets, capsules, syrups, suspensions, emulsions, gels, and creams during analytical method development, in-process control, and batch release stages.

3. Responsibilities

• Formulation Analyst: Collects and prepares representative samples for color evaluation.
• Analytical Scientist: Develops and validates color measurement methods using calibrated equipment.
• QA Officer: Reviews results against product specifications.
• Head – AMD: Approves methods and ensures method integration with QMS.

4. Accountability

The Head of Analytical Method Development is accountable for ensuring the accuracy, objectivity, and traceability of all color uniformity measurements conducted for pharmaceutical products.

5. Procedure

5.1 Instrument Selection and Calibration

1. Use one of the following:
   • Colorimeter (e.g., CIE L*a*b* system)
   • UV-Visible Spectrophotometer (λ max method for colored solutions)
2. Calibrate instruments using standard white and black tiles for colorimeter or reference standards for spectrophotometer.
3. Document calibration in Annexure-1: Instrument Calibration Log.

5.2 Sample Preparation

1. For solid oral dosage forms:
   • Randomly select 10 units.
   • Place one unit at a time on the colorimeter sample plate and measure surface color at three distinct points.
2. For liquids or semisolids:
   • Stir the sample gently to homogenize.
   • Transfer aliquot to a quartz or clear cuvette (1 cm pathlength).
3. Ensure consistent lighting (D65) and observation angle (10°) for all measurements.

5.3 Measurement Parameters

1. For colorimeter:
   • Record L* (lightness), a* (red/green), and b* (yellow/blue) values.
   • Calculate average ΔE* (total color difference) between test and reference samples.
2. For UV-visible spectrophotometer:
   • Record absorbance at formulation-specific λ max (e.g., 420 nm for yellow colorants).
   • Compare absorbance readings across batches and sample locations.

5.4 Acceptance Criteria

1. For colorimeter: ΔE* ≤ 2.0 indicates acceptable color uniformity.
2. For spectrophotometer: RSD ≤ 2% between readings.
3. Record findings in Annexure-2: Color Uniformity Report.

5.5 Method Validation

1. Validate per ICH Q2(R2):
   • Precision: RSD ≤ 2% across replicate measurements.
   • Linearity: Standard color solutions across concentration range (R² ≥ 0.998).
   • Accuracy: Measured value recovery between 98–102% of true value.
   • Robustness: Reproducibility under varying light sources or observers.
2. Summarize in Annexure-3: Validation Summary.

6. Abbreviations

• RSD: Relative Standard Deviation
• ΔE*: Total Color Difference
• QMS: Quality Management System
• SOP: Standard Operating Procedure
• CIE: Commission Internationale de l’Éclairage

7. Documents

1. Instrument Calibration Log – Annexure-1
2. Color Uniformity Report – Annexure-2
3. Validation Summary – Annexure-3

8. References

• ICH Q2(R2) – Validation of Analytical Procedures
• USP <1061> – Color and Appearance
• Ph. Eur. 2.2.2 – Degree of coloration of liquids

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Instrument Calibration Log

Date	Instrument ID	Standard Tile/Ref.	L*	a*	b*	Analyst
18/05/2025	CLM-112	White Tile	94.3	-0.1	1.2	Rajesh Kumar

Annexure-2: Color Uniformity Report

Batch No.	Formulation Type	ΔE*	Acceptance Criteria	Status
BT-112	Tablet	1.7	≤ 2.0	Complies

Annexure-3: Validation Summary

Parameter	Result	Criteria	Status
Precision	RSD = 1.6%	≤ 2%	Pass
Linearity	R² = 0.9987	≥ 0.998	Pass

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
04/05/2025	2.0	Expanded scope to include UV-Vis method and updated acceptance limits	Annual SOP Review