Mass spectrometric profiling of saturated fatty acid esters of steroids separated by high-temperature gas chromatography

An efficient analytical method for simultaneous determination of 12 SFEs in serum is described. The method involves solid-phase extraction to isolate of SFEs from interfering species, especially cholesteryl esters, conversion to trimethylsilyl (TMS) ether derivatives for the direct analysis by gas chromatography-mass spectrometry (GC-MS) using a high temperature MXT-1 (Silcosteel-treated stainless steel) capillary column. All SFEs as their TMS derivatives were well separated with excellent peak shapes within 12 min. Overall recoveries ranged from 88% to 119%, with a detection limits for SFEs ranged from 2 to 30 mu g L-1. The linearity as correlation coefficient was higher than 0.99 except for pregnenolone-3-arachidate (r(2) = -0.98) in the concentration range of 5-3000 mu g L-1. Ten serum samples obtained from volunteers were also analyzed and quantitatively determined of DHEA-3-palmitate and pregnenolone-3-stearate in 1.8-1195.8 mu g L-1 concentration. The devised high temperature GC-MS method could be useful for identification of SFEs in biological specimens including serum. (C) 2008 Elsevier B.V. All rights reserved.