Gas chromatographic-mass spectrometric determination of plasma saturated fatty acids using pentafluorophenyldimethylsilyl derivatization

An improved method for the detection of 11 saturated fatty acids (SFAs) inc luding C12:0-C26:0 (even numbers only), C17:0, C19:0 and C23:0 in human pla sma by gas chromatography-mass spectrometry (GC-MS) with a stable isotope i nternal standard as d(3)-stearic acid is described. This procedure was base d on acidic treatment, liquid-liquid extraction, and chemical derivatizatio n prior to instrumental analysis. Eleven pentafluoropbenyldimethylsilyl-SFA derivatives were well separated without any interfering peaks in plasma sa mples. The characteristic ions at M-15, constituting the base peaks in the electron impact mass spectra for 11 SFAs, permitted their sensitive detecti on by GC-MS in the selected ion monitoring (SIM) mode. The SIM responses we re linear with correlation coefficients varying from 0.993 to 0.999 in the concentration range of 0.05 similar to 50 mu g/ml for the 11 SFAs. The dete ction limits for SLM of the SFAs varied in the range of 0.05 similar to 10. 0 pg. When applied to the plasma samples of normal subjects and patients wi th X-linked adenoleukodystrophy, which is one of the hereditary peroxisomal disorders, the present method enabled us to determine the SFAs with good s ensitivity and good overall precision and accuracy within the concentration ranges of 0.14 similar to 82.35 mu mol/l. (C) 2000 Elsevier Science B.V. A ll rights reserved.