Aeration of ethylene oxide-sterilized polymers.

The ethylene oxide (EO) content of 17 polymers sterilized with 100% EO under conditions normally used in practice was determined as a function of aeration time, and for some polymers also as a function of sample thickness. The determination of the amount of residual EO has been carried out by gas chromatography, applying Discontinuous Gas Extraction and Head Space analysis. Generally, aeration was confirmed to be a diffusion-controlled process. Diffusion coefficients of EO for the investigated materials were determined from the rates of desorption. For a number of materials the EO content appeared to be well above the levels for EO which currently are considered to be safe, even after aeration for 15 d. For a reliable determination of aeration times required for EO-sterilized medical devices, the type and in particular also the thickness of the material from which the device is made should be considered.