title: Determination of free cholesterol oxide products in food samples by gas chromatography and accelerated solvent extraction: influence of electron-beam irradiation on cholesterol oxide formation.
abstract: BACKGROUND
  The aim of this study was to develop an efficient method for cholesterol oxide product (COP) determination in irradiated and non-irradiated ready-to-eat foods with high water content by gas chromatography-flame ionisation detector after accelerated solvent extraction (ASE), and derivatisation with a silylating reagent.
  
  
  RESULTS
  The ASE solvent was an 85:15 v/v petroleum ether/chloroform mixture at 40 °C and 1500 psi followed by solid phase extraction. The ASE method was compared with the established lixiviation method, proving an advantageous alternative which reduces analysis time by a factor of 15 and solvent volume by 50%, and minimises the use of chlorinated solvents. COP derivative structures were identified by gas chromatography coupled with mass spectrometry. Analytical characteristics were determined from standards and recoveries were 63-95%, establishing the validity of the method.
  
  
  CONCLUSIONS
  The results obtained and their analysis by chemometric techniques established COP formation in food samples after e-beam irradiation. Increase in COP concentration depended on both irradiation doses and food composition, mainly water and fat content, although linear correlations among variables were not found. © 2016 Society of Chemical Industry.
authors.affiliation: Department of Chemistry, Faculty of Science, Nariño University, Colombia.
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Lozada-Castro
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, 28040, Madrid, Spain.
authors.forename: María Jesús
authors.identifier: http://orcid.org/0000-0002-1995-028X
authors.initials: MJ
authors.lastname: Santos-Delgado
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, 28040, Madrid, Spain.
authors.forename: Luis María
authors.initials: LM
authors.lastname: Polo-Díez
mesh_terms: D000818:Animals; D002611:Cheese / Q000032:analysis / Q000528:radiation effects; D002784:Cholesterol / Q000032:analysis* / Q000096:biosynthesis / Q000378:metabolism / Q000528:radiation effects*; D002849:Chromatography, Gas / Q000379:methods; D004583:Electrons; D005223:Fats / Q000032:analysis; D005504:Food Analysis / Q000379:methods*; D005506:Food Contamination / Q000032:analysis*; D008460:Meat / Q000032:analysis / Q000528:radiation effects; D010087:Oxides / Q000032:analysis* / Q000378:metabolism / Q000528:radiation effects*; D000069466:Red Meat / Q000032:analysis / Q000528:radiation effects; D012474:Salmon / Q000033:anatomy & histology; D052616:Solid Phase Extraction / Q000379:methods; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000032:analysis
chemical_list: D005223:Fats; D010087:Oxides; D012997:Solvents; D014867:Water; D002784:Cholesterol
keywords: accelerated solvent extraction; cholesterol oxide products; derivatisation; e-beam irradiation; food samples of animal origin; gas chromatography