Report on investigation of ISO 10993-12 extraction conditions

The international standard ISO 10993-12 describes extraction conditions for generating extracts of medical devices to be used in testing of biological safety. Questions about the adequacy of the extraction conditions (and their variations) for hazard identification drove the development and execution of a round robin study. Four relevant device materials were each evaluated by four laboratories following an established protocol that specified multiple options of extraction solvent, temperature, duration, and ratio of solvent volume to quantity of test article. The resulting samples were analysed by three instrumental methods to identify and quantify extracted organic and elemental substances; however, quantification was not achieved due to lab resource constraints, and only numbers of compounds were reported. Results showed an increased number of volatile organic compounds extracted with organic solvents; however, no clear effect of varying the other extraction parameters could be discerned. Quantification of a small subset of analytes showed sensitivity that may be adequate for hazard identification. An unplanned post hoc comparison of results across labs showed differing numbers of compounds detected; however, fundamental differences in sample preparation and specific analysis methods as well as lack of quantification render the results poorly suited to either exonerate or indict the adequacy of chemical characterization as practiced by the participating laboratories.