The Water Pressure Integrity Test--a new integrity test for hydrophobic membrane filters.

Sterilizing grade hydrophobic filters are used for the sterile filtration of gases in pharmaceutical and biological applications. Until now the integrity of these membrane filters and their ability to retain bacteria, has been correlated to a solvent based nondestructive integrity test. Current methods use solvents to wet the membranes in order to perform bubble point and diffusion integrity tests. Solvent based integrity tests make it difficult to test in situ following sterilization because of the risk of downstream solvent contamination. A newly developed method, the Water Pressure Integrity Test (WPIT), allows for the integrity testing of hydrophobic filters eliminating the problems associated with traditional test methods employing solvents. A prime advantage of WPIT is that it may be performed in situ post sterilization without any downstream manipulations. The test has been directly correlated to the retention of bacterial challenges. Data will be provided to show the reliability and sensitivity of this easy to perform test.