A new method for measuring porous microbial barriers: Part II A closer look at ASTM international standard test method

Balloting on a new test method for use in the ranking of porous packaging materials used in sterile packaging applications by their ability to provide bacterial holdout was completed in July 2007 by ASTM International Committee F02 Flexible Barrier Packaging. As a result of this balloting, there is a new test method available for evaluating the barrier capabilities of porous materials intended for use in the packaging of terminally sterilized products. This new test method, ASTM F2638-07 Standard Test Method for Using Aerosol Filtration for Measuring the Performance of Porous Packaging Materials as a Surrogate Microbial Barrier, utilizes an aerosol of 1.0μm diameter polystyrene spheres to measure the filtration efficiency of porous materials. Unlike its predecessor, ASTM F1608-00(2004), Standard Test Method for Microbial Ranking of Porous Packaging Materials (Exposure Chamber Method), which uses actual spores of a nominal 1.0 μm size for testing and can take several days to produce results, the apparatus defined in the new ASTM F2638-07 test method can provide almost instantaneous test results.