Simultaneous determination of trace sterols in complicated biological samples by gas chromatography-mass spectrometry coupled with extraction using β-sitosterol magnetic molecularly imprinted polymer beads

In this paper, an efficient and sensitive analytical method for the simultaneous determination of three trace sterols including ergosterol, stigmasterol and beta-sitosterol in complicated biological samples was developed by gas chromatography-mass spectrometry (GC-MS) coupled with extraction using novel beta-sitosterol magnetic molecularly imprinted polymer (mag-MIP) beads. Physical tests suggested that beta-sitosterol mag-MIP beads prepared by a rapid microwave synthesis method possessed the porous morphology, narrow size distribution, stable chemical and thermal property. Due to the greatly enlarging surface area and the strong recognition to the target molecules, beta-sitosterol mag-MIP beads have a higher enrichment factor for beta-sitosterol (similar to 20-fold) and the higher selectivity for beta-sitosterol and its analogs than that of beta-sitosterol magnetic nonimprinted polymer (mag-NIP) beads. Under the optimum analytical conditions, all the target compounds achieved good chromatographic separation and sensitive detection without matrix interference. It was interesting that three target sterols were actually found in mushroom samples, and stigmasterol and beta-sitosterol were actually found in serum and watermelon samples. The recoveries of spiked sample tests were in range of 71.6-88.2% with RSDs of 2.4-10.0% (n = 3). This method is reliable and applicable for the simultaneous determination of trace sterols in real biological samples based on the beta-sitosterol mag-MIP bead extraction. (C) 2011 Elsevier B.V. All rights reserved.