Methods to Evaluate Cleaners and Sanitizers

Abstract

Methods to evaluate germicides can be grouped into three categories: standard laboratory tests, in-use tests and simulated-use tests. Standard laboratory methods, such as the Available Chlorine Germicidal Equivalent test, are specifically defined for reproducibility in any laboratory by any operator, but the test results often lack relevance to actual product-use conditions. In-use test methods are relevant to product-use; however, in-use test procedures do not permit proper controls to be included in the organism recovery methods. Contact plates give an estimate of organism numbers which is only 25% of the theoretical number of organisms present. Organism recovery using a swab, cellulose sponge or tube sampler give estimates of organisms ranging from 91 to 111% of theoretical. The tube sampler is a 1-in. length of flexible tubing having a 1-in. interior diameter and a smooth end, which can make a water-tight seal on a flat surface. Simulated use testing yields data which are relevant to actual product-use. A cafeteria tray is soiled, inoculated and cleaned in a manner to simulate actual product-use. This test method permits the necessary controls to be used. Tray-test reproducibility is as good as that of the other recovery methods tested and organism recovery is quantitative. The tray test provides a means for determining biological cleaning where the effect of both cleaning and germicidal activity are measured together.