Variables affecting simulated use determination of residual ethylene oxide in medical devices

In autumn 1993, AAMI/ST/WG 63, Sterilization Residuals Working Group undertook the task of studying factors involved in determining the amount of residual ethylene oxide in medical devices after sterilization and developing a protocol for controlling the relevant variables. The protocol was evaluated by conducting a round robin study consisting of 8 participating laboratories from around the country. Results of this round robin study demonstrated the range over which results may vary despite controls placed on the time and temperature at which determinations were conducted. The data from the study suggest that small, random variations in technique during short sample extraction times can lead to variability in the results. Variables such as initial water temperature, oven temperature, weighing of sample, and length of extraction should be carefully controlled. Inherent variations in the material composition of similar devices are possible contributing factors. The efforts of this working group and the subsequent evaluation and discussion of its findings are presented.