Comparative Evaluation of Quantitative Test Methods for Gases on a Hard Surface
Abstract
In this study, two quantitative test methods were evaluated (the Three Step Method [TSM] and the Quantitative Disk Carrier Test [QCT]) for determining the efficacy of chlorine dioxide (CD) gas and vaporous hydrogen peroxide (VHP) against spores of Bacillus subtilis. The tests were performed at three efficacy levels (low, medium, and high). Steel carriers, inoculated with 7 logs of spores, were exposed to 250, 500, and 3000 parts per million volume (ppmv/h) concentration time (CT) of CD gas or 150, 450, and 900 ppmv/h CT of VHP. For the high-CD treatment, testing resulted in a narrow range of log reduction (LR;67) for both methods; however, for the medium- and low-CD treatments, the variable LR values ranged between 4 and 5 for QCT and 2 and 4.5 for TSM. The standard deviation (SD; 0.52.5 log) was high for the medium- and low-CD treatments. For VHP, a value of >6 LR was observed with QCT for each treatment level, and mean LR values of 2, 3.5, and 4.5 for the low, medium, and high treatment levels, respectively, were observed with TSM. TSM was more sensitive to the treatment level, and the high variability could have resulted from poor gas penetration.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 2017
- Accession Number
- AD1034269
Entities
People
- Smith S Lisa
- Vipin Rastogi
- Wallace Lalena
Organizations
- Edgewood Chemical Biological Center