conditions.

2. Scope

This SOP is applicable to the Analytical Method Development (AMD) and Quality Control (QC) departments for the analysis and validation of osmolality measurements in parenteral dosage forms, including solutions, emulsions, and suspensions.

3. Responsibilities

• Analytical Scientist: Performs osmolality testing using a calibrated osmometer and documents results.
• QC Analyst: Prepares test samples and reference standards for measurement.
• QA Executive: Reviews test records and ensures adherence to regulatory and compendial requirements.

4. Accountability

The Head of Analytical Method Development is accountable for ensuring the method is validated, suitable for intended use, and compliant with pharmacopeial standards.

5. Procedure

5.1 Principle

Osmolality is measured based on the depression of the freezing point of a solution relative to pure solvent, expressed in milliosmoles per kilogram of water (mOsm/kg H₂O).

5.2 Equipment and Materials

1. Freezing Point Depression Osmometer (e.g., Advanced Instruments or equivalent)
2. Calibrated osmolality reference standards (100, 290, and 1000 mOsm/kg)
3. Sterile syringes, vials, and sample tubes

5.3 Calibration

1. Calibrate osmometer using three-point standardization (100, 290, 1000 mOsm/kg) before use (Annexure-2).
2. Acceptable recovery: ±2% of nominal value.
3. Recalibrate daily or after 20 consecutive runs.

5.4 Sample Preparation

1. Use 100–250 µL of the injection sample directly or diluted as per formulation requirement.
2. Degas or equilibrate to room temperature (20–25°C) before analysis.
3. Handle under aseptic conditions to avoid contamination.

5.5 Test Execution

1. Clean the sample probe with WFI and wipe dry before and after each test.
2. Aspirate the sample into the sample holder using a micropipette.
3. Insert into the osmometer; initiate automatic freezing and readout.
4. Document osmolality value in mOsm/kg with sample ID, batch number, and operator initials.

5.6 Acceptance Criteria

• Isotonic range: 270–310 mOsm/kg H₂O (physiological tolerance)
• For hypertonic/hypotonic products, permissible range defined in product specification dossier
• Deviation from specification requires justification and impact assessment on safety/efficacy

5.7 Method Validation Parameters

1. Accuracy: Recovery within ±2% of standard values
2. Precision: RSD ≤1.5% over 6 replicate injections
3. Linearity: r² ≥ 0.999 between 100–1000 mOsm/kg
4. Robustness: Test reproducibility under temperature and time delays

6. Abbreviations

• QA: Quality Assurance
• WFI: Water for Injection
• RSD: Relative Standard Deviation
• mOsm/kg: Milliosmoles per Kilogram

7. Documents

1. Osmolality Test Log – Annexure-1
2. Calibration Certificate – Annexure-2
3. Validation Summary Report – Annexure-3

8. References

• USP <785>: Osmolality and Osmolarity
• Ph. Eur. 2.2.35: Osmolality
• 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	Anuradha Tiwari	Mahesh Pillai	Sunita Reddy
Designation	Senior Analyst	QA Reviewer	Head – AMD
Department	Analytical Method Development	QA	Analytical Method Development

11. Annexures

Annexure-1: Osmolality Test Log

Sample ID	Batch No.	Volume Tested (µL)	Osmolality (mOsm/kg)	Status
INJ-269-01	21052302	100	288	Pass

Annexure-2: Calibration Certificate

Standard Value (mOsm/kg)	Observed Value	Recovery (%)	Status
100	99.2	99.2%	Pass
290	292.5	100.9%	Pass
1000	1003	100.3%	Pass

Annexure-3: Validation Summary Report

The osmolality method for injectable formulations including sodium chloride injection and multivitamin preparations was validated. Accuracy (99–101%), precision (RSD = 1.2%), and robustness across multiple analysts were confirmed. Method approved for routine QC and stability programs.

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
21/05/2025	2.0	Updated calibration procedure and validation parameters	Annual Review	Sunita Reddy
20/03/2022	1.0	Initial SOP Release	New SOP	QA Head