Computerized model for accurate determination of ethylene oxide diffusion in sterilized medical supplies

A computerized numerical model is described which is shown to be more generally applicable than analytical methods in the determination of ethylene oxide diffusion in polymeric material. Diffusion coefficients of ethylene oxide in poly(vinyl chloride) were determined from the rates of desorption both for conventional aeration with warm air and for microwave-assisted desorption and found to be concentration dependent. The model takes account of device geometry and concentration dependence of diffusion coefficient and its predictions are in agreement with experimental results for desorption. The model is also used to simulate the whole sterilization process with a view to a planned diminution of EO residuals after sterilization.