title: On-line liquid chromatography-gas chromatography: A novel approach for the analysis of phytosterol oxidation products in enriched foods.
abstract: A novel methodology for the automated qualitative and quantitative determination of phytosterol oxidation products in enriched foods via on-line liquid chromatography-gas chromatography (LC-GC) was established. The approach is based on the LC pre-separation of acetylated phytosterols and their corresponding oxides using silica as stationary phase and a mixture of n-hexane/methyl tert-butyl ether/isopropanol as eluent. Two LC-fractions containing (i) 5,6-epoxy- and 7-hydroxyphytosterols, and (ii) 7-ketophytosterols are transferred on-line to the GC for the analysis of their individual compositions on a medium polar trifluoropropylmethyl polysiloxane capillary column. Thus, conventionally employed laborious off-line purification and enrichment steps can be avoided. Validation data, including recovery, repeatability, and reproducibility of the method, were elaborated using an enriched margarine as example. The margarine was subjected to a heating procedure in order to exemplarily monitor the formation of phytosterol oxidation products. Quantification was performed using on-line LC-GC-FID, identification of the analytes was based on on-line LC-GC-MS. The developed approach offers a new possibility for the reliable and fast analysis of phytosterol oxidation products in enriched foods.
authors.affiliation: Lehrstuhl für Allgemeine Lebensmitteltechnologie, Technische Universität München, Maximus-von-Imhof-Forum 2, D-85350 Freising, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Scholz
authors.affiliation: Lehrstuhl für Allgemeine Lebensmitteltechnologie, Technische Universität München, Maximus-von-Imhof-Forum 2, D-85350 Freising, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wocheslander
authors.affiliation: Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit, Veterinärstrasse 2, D-85764 Oberschleissheim, Germany.
authors.forename: Vera
authors.initials: V
authors.lastname: Lander
authors.affiliation: Lehrstuhl für Allgemeine Lebensmitteltechnologie, Technische Universität München, Maximus-von-Imhof-Forum 2, D-85350 Freising, Germany. Electronic address: k.h.engel@wzw.tum.de.
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Engel
mesh_terms: D002849:Chromatography, Gas / Q000379:methods; D002853:Chromatography, Liquid / Q000379:methods; D005527:Food, Fortified / Q000032:analysis*; D006358:Hot Temperature; D008383:Margarine / Q000032:analysis; D010084:Oxidation-Reduction; D010840:Phytosterols / Q000737:chemistry*; D015203:Reproducibility of Results
chemical_list: D010840:Phytosterols; D008383:Margarine
keywords: Enriched foods; On-line LC–GC; Phytosterol oxidation products