Submitted on March 20, 2008
Revised on May 19, 2008
Accepted on May 21, 2008
Highly sensitive analysis of sterol profiles in human serum by LC-ESI-MS/MS
Akira Honda, Kouwa Yamashita, Hiroshi Miyazaki, Mutsumi Shirai, Tadashi Ikegami, Guorong Xu, Mitsuteru Numazawa, Takashi Hara, and Yasushi Matsuzaki
Tokyo Medical University, Kasumigaura Hospital, Ami, Ibaraki 300-0395
Corresponding Author: ymatsuzaki-gi{at}umin.ac.jp
We have developed a highly sensitive and specific method for the analysis of serum sterol profiles. Sterols in 1 
l of dried serum were derivatized into picolinyl esters (3
-picolinate) and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using the electrospray ionization (ESI) mode. In addition to cholesterol, 19 cholesterol precursors, cholestanol, campesterol, sitosterol and sitostanol were identified simultaneously. Quantitative analyses for the picolinyl esters of 11 available sterols were performed and detection limits were found to be less than 1 pg on-column. Reproducibilities and recoveries of 8 non-cholesterol sterols were validated according to one-way layout and polynomial equation, respectively. The variances between sample preparations and between measurements by this method were calculated to be 1.6 to 8.2% and 2.5 to 16.5%, respectively. The recovery experiments were performed using 1 l aliquots of normal human serum spiked with 1 to 6 ng of sterols, and recoveries of the sterols ranged from 88.1 to 102.5% with a mean recovery of 98.1%. The present method provides reliable and reproducible results for the identification and quantification of neutral sterols, especially in small volumes of blood samples, which is useful for serological diagnosis of inherited disorders in cholesterol metabolism and for non-invasive evaluation of cholesterol biosynthesis and absorption in humans.
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