Giglia Sal, Alembath Anand, Hersey Joseph
EMD Millipore Corporation, an Affiliate of Merck, Bedford, MA 01730, USA.
Membranes (Basel). 2023 Jan 10;13(1):88. doi: 10.3390/membranes13010088.
Bubble point tests are widely used for assessing the integrity of sterilizing-grade membrane cartridge filters. While many authors have considered the limitations of bubble point tests as applied to cartridge filters, the level of bacterial retention assurance provided by this test as conducted with automated integrity testers (AITs) has not, until now, been quantified. Contrary to the notion that filter leaks result in a depressed bubble point, it was shown that the bubble point as reported by AITs was insensitive to defect size up until the point where the AIT either determined a gross leak failure or was not able to return a valid result. For the three AITs used in this study, the minimum laser hole defect diameter in 10-inch (25.4 cm) sterilizing-grade cartridge filters that resulted in a failing bubble point test was between about 30 and 60 µm, depending on the filter type and test conditions. These defect sizes were associated with bacterial log reduction values in the 4.0 to 4.5 range. This study supports the generally recommended practice of pairing the bubble point test (which does confirm proper pore size rating) with a complementary gas-liquid diffusion test (better suited for detecting defects) to achieve a more comprehensive assessment of filter integrity.
泡点测试被广泛用于评估除菌级膜筒式过滤器的完整性。虽然许多作者已经考虑到泡点测试应用于筒式过滤器时的局限性，但直到现在，使用自动完整性测试仪（AIT）进行此项测试所提供的细菌截留保证水平尚未得到量化。与过滤器泄漏会导致泡点降低的观念相反，研究表明，在AIT判定出现严重泄漏故障或无法返回有效结果之前，AIT报告的泡点对缺陷大小不敏感。对于本研究中使用的三台AIT，在10英寸（25.4厘米）除菌级筒式过滤器中，导致泡点测试失败的最小激光孔缺陷直径约在30至60微米之间，具体取决于过滤器类型和测试条件。这些缺陷尺寸对应的细菌对数减少值在4.0至4.5范围内。本研究支持将泡点测试（确实能确认合适的孔径规格）与互补的气液扩散测试（更适合检测缺陷）相结合的普遍推荐做法，以实现对过滤器完整性更全面的评估。
