Concentration of phytosterols for analysis by supercritical fluid extraction

Fractionation of sterols from plant lipid mixtures was accomplished using a multistep supercritical fluid extraction (SFE) procedure. Samples of seed oils, margarine, corn germ oil, and corn fiber oil were extracted to yield enriched phytosterol fractions. Supercritical fluid chromatography (SFC) was utilized to separate and determine the concentration of the plant sterols in the extracts from the various samples. The sterol concentration in the original samples varied from 2.2 mg/g in soybean oil to 13.2 mg/g in oil extracted from corn fiber. After the SFE-based fractionation of the samples, the sterol concentration was increased to 64.4 mg/g in the extract from soybean oil and 166.2 mg/g in the extract from corn fiber oil. Oil extracted from corn bran, which measured 8.6 mg/g in the original oil, increased to 322.2 mg/g using the fractionation process. The benign conditions utilized by SFE and SFC proved to be effective for the analyses of these compounds without inducing degradation of the analytes.