Automatic Detection Of Improper Test Setup Of A Filter Integrity SystemSource: Sartorius Stedim Biotech
Filter integrity testing is a crucial requirement in biopharmaceutical production processes. Automatic test units perform indirect tests to verify the pore size to be as specified for a sterilizing-grade membrane filter. Different test methods are established for which a specific test pressure is applied to a wetted membrane. In most cases self-closing quick connectors (e.g. Stäubli couplings) are used for pneumatic connection of the test tubing from the integrity tester to the test housing. In case of an inadvertently disconnected filter housing, the normally-closed coupling will cause the test unit to only pressurize the internal test tubing and not the filter housing. In that situation, the integrity tester will not detect any significant diffusion rate or any relevant nonlinearity in flow, which is needed to detect the bubble point. However, as the only criteria for the test evaluation, a maximum diffusion rate and | or minimum bubble point is defined. Both criteria (max. diffusion rate is not exceeded and bubble point is greater than minimum BP) might be fulfilled when only the tubing is tested. In that situation an integrity test without any filter might be classified as "test passed," which indeed is a false positive test result.