AOAC Use Dilution Test for Liquid Disinfectants (Methods 964.02, 955.14 and 955.15)

Purpose of Test

The AOAC Use Dilution test method is a carrier-based method used to evaluate disinfection efficacy of water soluble powders and non-volatile liquid products for registration with regulatory agencies such as the U.S. EPA, Health Canada and in the case of high-level disinfectants, the U.S. FDA. This method is intended to simulate and evaluate products intended for mop or soak-based applications.

Summary of Test

In this method, a series of stainless steel cylinders (“carriers”) are inoculated with a representative test organism and the carriers are dried. The carriers containing the dried organism film are then sequentially immersed into 10 mL of disinfectant and are exposed to the disinfectant for a pre-determined exposure time. After exposure, the carriers are sequentially transferred to a liquid subculture medium specifically selected to neutralize the test substance active and to recover any surviving test organism. The carriers are incubated and visually examined for the presence or absence of growth. Based on the desired disinfection claim and the requirements of the regulatory agency, the product must demonstrate kill on a pre-determined number of carriers inoculated with test organisms applicable to the claim. Standard disinfection organisms include but are not limited to: Staphylococcus aureus, Salmonella enterica, and Pseudomonas aeruginosa. Additional pathogens of clinical, occupational or household relevance including fungi are often tested.