Procedure for pH Determination in Semisolids
1) Purpose
The purpose of this SOP is to outline the procedure for determining the pH of semisolid pharmaceutical formulations to ensure their quality and consistency.
2) Scope
This SOP applies to all semisolid formulations (e.g., creams, ointments, gels) manufactured within the facility that require pH determination as part of quality control testing.
3) Responsibilities
Quality Control (QC) Department: Responsible for conducting pH determination and ensuring compliance with this SOP.
Production Department: Responsible for providing semisolid samples and supporting QC during testing.
4) Procedure
4.1 Equipment Preparation:
4.1.1 Verify and calibrate the pH meter and electrodes according to the manufacturer’s instructions.
4.1.2 Ensure adequate supply of calibration buffers (pH 4.0, pH 7.0, pH 10.0) and distilled water.
4.1.3 Perform pH meter suitability checks using standard solutions before testing.
4.2 Sample Preparation:
4.2.1 Obtain representative samples of semisolid formulations from different batches.
4.2.2 Mix samples thoroughly to ensure homogeneity before pH measurement.
4.2.3 Allow samples to equilibrate to room temperature if necessary.
4.3 pH Measurement:
4.3.1 Calibrate the pH meter using standard pH buffers (pH 4.0, pH 7.0, pH 10.0) before each measurement session.
4.3.2 Immerse the pH electrode into the sample without touching the container walls.
4.3.3 Record the pH reading once stabilized on the meter display.
4.3.4 Rinse and recalibrate the electrode between different samples to prevent cross-contamination.
4.4 Interpretation of Results:
4.4.1 Compare measured pH values against acceptance criteria specified in pharmacopeial standards or internal specifications.
4.4.2 Document pH measurement results accurately, including any deviations from expected values.
4.4.3 Investigate and resolve discrepancies or out-of-specification results promptly.
4.5 Acceptance Criteria:
4.5.1 Semisolid formulations are considered acceptable if their pH values fall within predefined limits.
4.5.2 Ensure all pH measurements adhere to validated procedures and method validation parameters.
4.6 Documentation:
4.6.1 Record all pH determination procedures, results, and observations in the pH Measurement Record.
4.6.2 Maintain detailed records of sample details, calibration logs, testing conditions, and any corrective actions taken.
4.6.3 Review and approve the documentation by QC Manager.
5) Abbreviations, if any
QC: Quality Control
6) Documents, if any
pH Measurement Record
pH Meter Calibration Certificates
Sampling Plan Document
7) Reference, if any
USP General Chapter <791> – pH
Pharmacopeial standards for pH Determination in Semisolids
8) SOP Version
Version 1.0
