were chlorinated by soaking them in a 10 solution of clorox buffered to ph 7 at ambient temperature for 45 minutes rinsed with water and dried for 1 hour at 45 u00b0 c to remove any occluded free chlorine an iodometric thiosulfate titration was used to measure the weight percent of cl bound to each swatch of cotton unchlorinated cotton swatches and unchlorinated coated cotton swatches served as controls in the biocidal tests to be described below biocidal efficacy tests were performed on the cotton swatches each swatch was inoculated with a 25 microliter drop of staphylococcus aureus atcc 6538 containing 9 47 u00d7 10 6 colony forming units cfu a second identical swatch was placed on top of the inoculated swatch as in a sandwich and was held in place by a steel weight following a specific contact time 5 10 and 30 minutes the bacterial cells were washed off the cotton with distilled deionized water while vortexing quenched with dilute sodium thiosulfate 0 02 n and plated onto trypticase agar colony counts were performed after incubation at 37 u00b0 c for 24 and 48 hours the results are shown in table 4 as can be seen from the results in table 4 all of the chlorinated coatings provided complete inactivation of s.