Analysis of low concentration additives; for example, antioxidants, in polymeric materials remains a difficult task. In the usual analytical methods, additives are extracted using large quantities of solvents first followed by concentrating the resulting solution for making possible the analysis. The supercritical fluid extraction (SFE) technique eliminates the use of large quantities of solvents and simplifies the analytical procedure. This work has been done with the goal of extracting the antioxidants Irganox 1010 and Irgafos 168 from a polypropylene matrix by using the SFE technique and by subsequent analysis using high-performance liquid chromatography (HPLC). The experimental parameters; that is, temperatures, pressure, and modifiers have been varied to find the best extraction conditions. The optimum temperature and pressure for extraction of above-mentioned polymer additives were found to be 120 degrees C and 384 bar, with methanol as the modifier. The quantitative extractions are significantly faster than those reported earlier in the literature. The results point out that the technique used in these experiments-SFE combined with HPLC-is a reliable and environmentally friendly alternative to the commonly used liquid extraction and analytical methods. (C) 2000 John Wiley & Sons, Inc.