Interlaboratory Comparison of Analytical Methods for Residual Ethylene Oxide at Low Concentration Levels in Medical Device Materials

An interlaboratory comparison of two extraction methods and one thermal desorption test method for the quantification of ethylene oxide (EO) by gas chromatography in two common medical device materials, high density polyethylene (HDPE) and plasticized polyvinyl chloride (PVC), was conducted by 15 laboratories. The three procedures included extraction with water, extraction with acetone, and headspace gas analysis, respectively. Materials were processed through an industrial EO cycle and aerated for various periods to achieve target levels of a low (5 μg/g), medium (10 μg/g), and high (25 μg/g) residual determination following extraction or thermal desorption. The results of this study, using only the data from the laboratories that did not deviate from the procedure, showed that the average estimated total coefficient of variation ranged from 3.63 to 12.42% for the three different methods. Each of the methods is suitable for use as a reference test method for determining residual EO in polymeric materials in the concentration range 2.8–42.3 μg/g.