title: Normal-phase liquid chromatography-atmospheric-pressure photoionization-mass spectrometry analysis of cholesterol and phytosterol oxidation products.
abstract: During thermal processing of sterols, complex mixtures of sterol oxidation products may be formed. Here, a new method for the separation and detection of such products is described. The method is based on normal-phase liquid chromatography (NPLC) for separation and atmospheric-pressure photoionization-mass spectrometry (APPI-MS) for detection. The method was optimized using commercial cholesterol oxidation products and tested on an experimentally derived mixture of phytosterol oxidation products. The investigated parameters include solvent and dopant selection, dopant concentration, polar modifiers, the type of stationary phase, and flow rate. Best chromatographic separation and highest sensitivity were achieved using a diol-bonded silica column, employing a solvent system consisting of hexane and isopropanol. The dopant of choice was chlorobenzene, added post-column to the solvent stream at 10% of the flow rate. The developed NPLC-APPI-MS method proved to be a valuable tool for the separation and detection of sterol oxidation products.
authors.affiliation: Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands. Electronic address: christian.grun@unilever.com.
authors.forename: Christian H
authors.initials: CH
authors.lastname: Grün
authors.affiliation: Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands.
authors.forename: Sophie
authors.initials: S
authors.lastname: Besseau
mesh_terms: D001274:Atmospheric Pressure; D002784:Cholesterol / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D010840:Phytosterols / Q000737:chemistry*; D012997:Solvents
chemical_list: D010840:Phytosterols; D012997:Solvents; D002784:Cholesterol
keywords: APPI–MS; Cholesterol; NPLC; Phytosterol; Sterol oxidation products