Simultaneous determination of four non-cholesterol sterols in like desmosterol human plasma using gas chromatography-mass spectrometry with selective ion monitoring / 中国药学杂志

ABSTRACT

OBJECTIVE: To establish a method for simultaneous determination of phytosterols and cholesterol precursors in human plasma by GC-MS to understand the metabolism of cholesterol in patients. METHODS: Sterols as TMS derivatives were separated and identified on HP-5MS column (30 m × 0.25 μm × 0.25 mm). The initial column temperature of 200°C. was held for 2 min, then increased at a rate of 15°C · min-1 to 280°C and maintained at this temperature for further 30 min. The internal standard was 5α-cholestane. The method was based on the alkaline hydrolysis of sterol esters, extraction of free sterols and derivatization. RESULTS: The calibration curves of the sterols were linear. Inter-day and intra-day RSDs were lower than 7.9% and 9.8%. The recoveries based on replicate analyses of plasma samples spiked with known amounts of sterol standards were between 89.5% - 106.3%. Plasma samples of 20 patients with hyperlipemia were determined by the method. The mean values of non-cholesterol sterols were desmosterol (0.39 ± 0.08) mg · L-1, lathosterol (3.41 ± 0.83) mg · L-1, campesterol (3.12 ± 0.53) mg · L-1, and sitosterol (4.22 ± 0.67) mg · L-1. CONCLUSION: An optimized analytical method for simultaneous analysis of cholesterol, desmosterol, lathosterol, campesterol and sitosterol in plasma has been developed using capillary gas chromatography coupled to mass spectrometry (GC-MS) with multiple selected ion monitoring (SIM). With good accuracy and precision, it is suitable for the analysis of the individual difference of cholesterol metabolism. Copyright 2012 by the Chinese Pharmaceutical Association.