Development of a universal diluting fluid for membrane filtration sterility testing.

A universal diluting fluid (UDF) was developed for use in membrane filtration sterility testing. Diuting fluid is used to free the filter membrane of preservative residues which could inhibit microbial recovery. Current procedures employ one of several fluids described by the United States Pharmacopeia. UF was designed to utilize the neutralizing capabilities of a combination of inactivating agents while minimizing any inherent microbial toxicity. This formulation eliminates the need for multiple types of preservative-specific diluting fluids. Its neutralizing effectiveness was examined against several common preservative agents used in health care products. UDF provides significantly better microorganism recovery than dilution alone among a wide range of preservative classes.