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[ 2 H/H] Isotope ratio analyses of [ 2 H 5 ]cholesterol using high‐temperature conversion elemental analyser isotope‐ratio mass spectrometry: determination of cholesterol absorption in normocholesterolemic volunteers
Author(s) -
Godin JeanPhilippe,
Richelle Myriam,
Metairon Sylviane,
Fay LaurentBernard
Publication year - 2004
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1336
Subject(s) - chemistry , analytical chemistry (journal) , analyser , mass spectrometry , chromatography , calibration curve , fractionation , isotope ratio mass spectrometry , detection limit
This paper validates the use of high‐temperature conversion elemental analyser isotope‐ratio mass spectrometry (TC‐EA/IRMS) for measuring the [ 2 H/H] enrichment of plasma [ 2 H 5 ]cholesterol. From a molecular point of view, the free cholesterol is initially separated from plasma by thin‐layer chromatography (TLC) and then injected onto the TC‐EA reactor which converts cholesterol molecules into CO and H 2 gases. The slope of the curve of the experimental mole percent excess (MPE (exp.) ) versus MPE (theor.) was very close to 1, demonstrating that no significant isotopic fractionation was observed during all processing of the samples (i.e., isolation of plasma free cholesterol by TLC and pyrolysis in the TC‐EA reactor). Excellent linearity (r 2 = 0.9994, n = 4) of δ (‰) of [ 2 H/H] isotopic measurements versus mole percent (MP) was assessed over the range 0 to 0.1 MP. The precision of the [ 2 H/H] measurement, evaluated with two calibration points processed with TLC, was δ 2 H V‐SMOW = −192.5 ± 3.4‰ and δ 2 H V‐SMOW = −136.9 ± 2.9‰. The standard deviations of the within‐assay and between‐assay repeatabilities of the analytical process, evaluated using the quality control (QC) of plasma samples, were 4.6 and 6.1‰, respectively. Plant sterols are known to reduce cholesterol absorption and therefore were used as a positive control in a clinical study performed with normocholesterolemic volunteers. This present method produces biological results consistent with those already reported in the literature. Copyright © 2004 John Wiley & Sons, Ltd.