Reverse micelle formation for acceleration of the supercritical fluid extraction of cholesterol from food samples

Reverse micelle formation is presented as a new strategy for improving the extraction of polar species with supercritical (SC) CO2. The addition of a reverse-micelle-forming reagent prior to SFE accelerates the quantitative extraction of the analyte. The effect was used to develop a method for the determination of cholesterol in solid foods. The proposed method involves the addition of a microemulsion of a nonionic surfactant (Triton X-100) to the sample and dynamic extraction with SC-CO2 at 383 bar and 40 degrees C for 20-40 min. The method was validated using a certified reference material (NIST-SRM 1845) and was subsequently used to analyze low-cholesterol (whole bread, oat biscuits, orange biscuits) and high-cholesterol foods (semiskimmed and whole milk) with excellent results (RSD <11% in all instances).