and formulations.

2. Scope

This SOP applies to the Analytical Method Development (AMD) team involved in using SEM for solid-state characterization of powders, granules, and other solid forms in pre-formulation and stability studies.

3. Responsibilities

• Analytical Scientist: Develops and interprets SEM data, ensures sample preparation is appropriate for analysis.
• Instrument Operator: Performs SEM imaging, maintains calibration, and ensures safe operation.
• QA Officer: Verifies analytical documentation and compliance with regulatory expectations.
• Head – AMD: Approves final SEM methodology and data interpretation for reporting.

4. Accountability

The Head of Analytical Method Development is accountable for ensuring scientifically valid and regulatory-compliant SEM methods are developed and maintained.

5. Procedure

5.1 Instrument Calibration and Preparation

1. Ensure the SEM is calibrated using a certified standard (e.g., gold nanoparticles or grid standards).
2. Verify magnification accuracy and beam alignment prior to analysis.
3. Record calibration details in Annexure-1: SEM Calibration Log.

5.2 Sample Preparation

1. Handle samples in a clean, static-free environment (e.g., laminar hood).
2. Place a small quantity of powdered sample onto a carbon tape attached to an SEM stub.
3. For non-conductive samples, apply a thin conductive coating (e.g., gold sputtering).
4. Ensure particles are spread as monolayer for optimal imaging.

5.3 Method Parameters and Imaging

1. Start SEM and set the following imaging parameters:
   • Acceleration Voltage: 5–20 kV (optimize based on sample type)
   • Working Distance: 8–12 mm
   • Magnification Range: 100x to 20,000x
   • Detector: Secondary Electron Detector (SE) for morphology
2. Focus beam and adjust brightness/contrast for each field of view.
3. Capture images at different magnifications for shape and surface feature assessment.
4. Document image file names, magnification, and sample details in Annexure-2: SEM Image Log.

5.4 Morphological Assessment

1. Evaluate the following parameters:
   • Particle shape: spherical, needle-like, rod, plate, irregular
   • Surface texture: smooth, porous, rough, crystalline
   • Size distribution visually (non-quantitative) or through software if integrated
2. Compare SEM images to reference polymorphic or crystal habit data if applicable.
3. Document conclusions in Annexure-3: Morphology Evaluation Report.

5.5 Method Validation

1. Validation may be qualitative or semi-quantitative depending on study purpose.
2. Parameters:
   • Specificity – Clear differentiation of particle types
   • Reproducibility – Imaging consistency across runs (same magnification and field)
   • Robustness – Sample mounting and coating variation effects
3. Summarize validation in Annexure-4: SEM Validation Summary.

6. Abbreviations

• SEM: Scanning Electron Microscopy
• SE: Secondary Electrons
• QA: Quality Assurance
• SOP: Standard Operating Procedure

7. Documents

1. SEM Calibration Log – Annexure-1
2. SEM Image Log – Annexure-2
3. Morphology Evaluation Report – Annexure-3
4. SEM Validation Summary – Annexure-4

8. References

• ICH Q6A – Specifications: Test Procedures and Acceptance Criteria
• USP <776> – SEM for Particle Morphology
• FDA Guidance on Particle Size Analysis and Visualization

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: SEM Calibration Log

Date	Standard Used	Magnification Verified	Analyst
18/05/2025	Gold Grid	Verified at 1000x and 10,000x	Rajesh Kumar

Annexure-2: SEM Image Log

Image ID	Sample ID	Magnification	Comments	Analyst
SEM-105	EXC-23	5000x	Porous spherical particles	Sunita Reddy

Annexure-3: Morphology Evaluation Report

Sample ID	Particle Shape	Surface Texture	Morphology Summary
API-SEM-107	Needle-like	Smooth	Uniform elongated crystals

Annexure-4: SEM Validation Summary

Parameter	Result	Criteria	Status
Reproducibility	Consistent morphology in triplicate images	Visual match	Pass
Robustness	Minor variation with coating time	No change in morphology	Pass

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
04/05/2025	2.0	Updated image documentation and added validation annexure	Annual SOP Review