Reverse-micelle formation: a strategy for enhancing CO2-supercritical fluid extraction of polar analytes

Reverse-micelle formation is revealed as a useful tool for improving the extraction of polar species by a non-polar extractant as supercritical (SC) CO2. As an example, the extraction of a medium polar analyte (cholesterol) by supercritical CO2 is dramatically improved in the presence of a non-ionic reverse micelle-former such as Triton X-100 (recoveries increased more than three times with respect to those obtained in the absence of the surfactant). Quantitation of the target analyte is performed by the Liebermann–Burchard photometric method, which provides a linear determination range between 40 and 500 μg/ml, with precision, expressed as relative standard deviation (R.S.D) of 2.62% for n=7.