Extraction and purification of free cholesterol from some egg-containing food by on-line supercritical fluid extraction - solid-phase extraction

Two methods for the extraction and determination of free cholesterol in som e egg-containing food samples were compared: the classical Soxhlet method a nd a supercritical carbon dioxide extraction (at 338 bar and 40 degreesC) c oupled on-line with solid-phase extraction (SPE with a solid trap packed wi th an ODS stationary phase). Egg noodles, biscuits and sweet snacks were ho mogenised and added to the internal standard and anhydrous sodium sulphate. Part of each sample was extracted by on-line supercritical fluid extractio n - solid-phase extraction (SFE-SPE) and the remaining part was extracted b y the classical method using petroleum ether. A further purification after the Soxhlet ex-traction was performed by SPE. Free cholesterol was determin ed in both the off-line Soxhlet-SPE fraction and the on-line SFE-SPE extrac t with capillary gas chromatography after silylation. The two extraction me thods gave similar results. However, on-line SFE-SPE represents a Valid alt ernative to the Soxhlet method because it shows important advantages, such as a short analysis time and low solvent consumption.