title: Comparison of cholesterol oxidation product preparation methods for subsequent gas chromatographic analysis.
abstract: An evaluation was made of the stability of cholesterol hydroperoxides (CHPs) under the analytical conditions and preparation methods commonly used for determination and quantification of cholesterol oxidation products (COPs). CHPs were prepared by photoxidation and separated by silica thin-layer chromatography. CHPs were individually collected by normal-phase liquid chromatography and then subjected either to reduction or to cold saponification. The corresponding hydroxyl derivatives were generated by reduction, whereas cold saponification gave rise predominantly to 7-ketocholesterol. In another test, silylated and non-silylated CHPs were separately injected into a gas chromatograph at 310 degrees C, collected, and re-injected into a gas chromatography-mass spectrometry system. The silylated CHPs were more stable than the non-silylated ones, giving 7-ketocholesterol, 7alpha- and 7beta-hydroxycholesterol as main degradation products. Two unknown degradation peaks were detected in both silylated and nonsilylated CHPs, having 384 as main m/z fragment. The study of their mass spectra led to the conclusion that peaks A and B correspond to 6alpha- and 6beta-hydroxycholesterol, respectively.
authors.affiliation: University of Bologna, Department of Food Science, Via Fanin 40, 40127 Bologna, Italy. estrada@sun.economia.unibo.it
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Rodriguez-Estrada
authors.forename: Arianna
authors.initials: A
authors.lastname: Costa
authors.forename: Marco
authors.initials: M
authors.lastname: Pelillo
authors.forename: Maria Fiorenza
authors.initials: MF
authors.lastname: Caboni
authors.forename: Giovanni
authors.initials: G
authors.lastname: Lercker
mesh_terms: D002784:Cholesterol / Q000378:metabolism*; D002849:Chromatography, Gas; D002853:Chromatography, Liquid; D013058:Mass Spectrometry; D010084:Oxidation-Reduction
chemical_list: D002784:Cholesterol