title: Gas chromatographic-mass spectrometric analyses of cholesterol and its precursors in rat plasma as tert-butyldimethylsilyl derivatives.
abstract: BACKGROUND
  Cholesterol and its metabolic precursors occurring in metabolic pathways are important biochemical indicators in pathological conditions.
  
  
  METHODS
  A method for the simultaneous determination of cholesterol and its metabolic precursors, such as lanosterol and 7-dehydrocholesterol, in rat plasma is demonstrated. It involves their extraction after saponification, followed by conversion to tert-butyldimethylsilyl (TBDMS) derivatives for analysis by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode (GC-SIM-MS).
  
  
  RESULTS
  The characteristic fragment ions of [M-57], m/z 443, 483, and 441 permitted the accurate and selective detection of cholesterol and its precursors in rat plasma. The whole procedure of TBDMS derivatization, with subsequent GC-SIM-MS analysis, was linear (r>or=0.9994), reproducible (% relative standard deviation=2.2 to 7.5), and accurate (% relative error=-5.6 to 7.7), with detection limits of 0.02 to 0.07 ng/ml. Recoveries were measured to be ranged from 89.5 to 95.4%.
  
  
  CONCLUSIONS
  The present method was useful for the quantification of cholesterol and its precursors in rat plasma samples of 1 microl.
authors.affiliation: Institute for Neuroregeneration and Stem Cell Research, School of Medicine, Ajou University, Suwon 443-721, Republic of Korea.
authors.forename: Man-Jeong
authors.initials: MJ
authors.lastname: Paik
authors.forename: Jundong
authors.initials: J
authors.lastname: Yu
authors.forename: Man-Bae
authors.initials: MB
authors.lastname: Hu
authors.forename: Sung-Jean
authors.initials: SJ
authors.lastname: Kim
authors.forename: Kyoung-Rae
authors.initials: KR
authors.lastname: Kim
authors.forename: Young-Hwan
authors.initials: YH
authors.lastname: Ahn
authors.forename: Sangdun
authors.initials: S
authors.lastname: Choi
authors.forename: Gwang
authors.initials: G
authors.lastname: Lee
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000097:blood*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D008297:Male; D008745:Methylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D002784:Cholesterol