Exhaustive soxhlet extraction for the complete removal of residual compounds to provide a nonleaching silicone elastomer

All commercially available silicone devices contain freely diffusible silic one oils, uncured oligomers, and other impurities (such as catalysts). Thes e residuals have been found in quantities as high as 20% by weight in comme rcially available silicone medical devices. The fate and effects of these r esiduals have been the topic of much debate recently, In this study, a meth od for complete removal of these residual compounds was investigated. The t otal amount of extractable residuals was determined through exhaustive Soxh let extraction of 5 silicone elastomers. LIM 6030 had 6.29%, LIM 6070 had 5 .74%, Q7-4750 had 3.02%, Q7-4780 had 3.22%, and SE1935 had 0.13% extractabl es by weight. The amount of silicon containing residuals leaching from both the extracted and nonextracted samples was also evaluated for 3 and 18 day s by inductively coiled plasma (ICP) analysis. A significant amount of leac hable compounds, reported as mu g Silmg solid sample, was found in all none xtracted elastomers with the exception of SE1935 compared to blanks. The am ount of leachable compounds found in the extracted elastomers was not found to be significantly higher than the amount found in the blanks. The residu al compounds in silicone elastomers may be completely removed by exhaustive Soxhlet extraction and the resulting polymer does not leach silicon-contai ning compounds in vitro. (C) 2000 John Wiley & Sons, Inc. J Biomed Mater Re s (Appl Biomater) 53: 445-448, 2000.