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Standard Operating Procedure: Blister Packaging Seal Integrity Testing

10/17/2026

Blister packaging requires rigorous seal integrity testing to ensure the protection of solid dose pharmaceuticals against environmental degradation, including light, thermal exposure, oxygen, and moisture. The following vacuum-based immersion protocol outlines the standardized methodology for verifying the hermetic sealing effectiveness of blister cards in accordance with industrial quality standards.

Working Principle

The integrity test operates on the principle of differential pressure. By evacuating a sealed, liquid-filled chamber containing the blister samples, an internal-to-external pressure differential is generated. Seal failure is identified either by the emission of air bubbles during the active vacuum phase or the infiltration of the liquid medium into the blister pockets post-test.

Equipment Specifications

  • Hermetically sealed testing chamber capable of withstanding internal pressures exceeding 1 atm.
  • Calibrated vacuum gauge (minimum accuracy class: 2.5).
  • Vacuum pump interface equipped with an isolation valve.
  • Atmospheric venting manifold and liquid supply connection.
  • Internal submergence plate to ensure samples remain fully submerged during the test cycle.

Standard Operating Procedure (SOP)

  1. Sampling: Randomly extract 100 blister cards from the production batch. Divide the sample pool into 4 analytical cohorts of 25 cards each.
  2. Preparation: Place the sample cohort into the testing chamber and submerge them in a distinctively colored indicator liquid. Secure the submergence plate, ensuring the liquid level is maintained at least 25mm above the highest sample surface.
  3. Vacuum Application: Seal the chamber cover tightly and close the atmospheric vent valve. Activate the vacuum pump to evacuate the chamber to a vacuum degree of 0.08 MPa (80 kPa). Maintain this precise pressure for exactly 30 seconds.
  4. Restoration & Extraction: Open the vent valve to restore standard atmospheric pressure within the chamber. Extract the samples, rinse them thoroughly with clean water, and dry the exterior surfaces completely.
  5. Visual Evaluation: Inspect each blister pocket and the surrounding sealing layers. The presence of any colored indicator liquid within the blister cavity or seal matrix definitively confirms a breach in hermetic integrity.