SPECIFICITY, ACCURACY, AND INTERPRETATION OF MEASUREMENTS OF ETHYLENE-OXIDE GAS CONCENTRATIONS DURING STERILIZATION USING A MICROWAVE SPECTROMETER

This article reports the update in the design of a microwave spectrome ter for measuring concentrations of ethylene oxide gas during steriliz ation. The specificity of the measurement (absorption line at 23.134 G Hz) using the spectrometer has been found to be virtually 100%. A grea t number of calibrations have been conducted in the range of concentra tions 100% to 40% of ethylene oxide gas at intervals of -10% in order to determine the accuracy of the spectrometer. It was found that the m aximum standard deviation from the regression curve was 1.2% full scal e (0%-100%). A mathematical model based on a diffusion equation has be en developed and was used to interpret the real time measurement data during sterilization. Numerical simulation using this model has demons trated that it is possible to predict the dynamic distributions of eth ylene oxide concentration within the load being sterilized. (C) 1997 A merican Institute of Physics.