title: Determination of n-alkanes in C. annuum (bell pepper) fruit and seed using GC-MS: comparison of extraction methods and application to samples of different geographical origin.
abstract: An efficient extraction and analysis method was developed for the isolation and quantification of n-alkanes from bell peppers of different geographical locations. Five extraction techniques, i.e., accelerated solvent extraction (ASE), ball mill extraction, ultrasonication, rinsing, and shaking, were quantitatively compared using gas chromatography coupled to mass spectrometry (GC-MS). Rinsing of the surface wax layer of freeze-dried bell peppers with chloroform proved to be a relatively quick and easy method to efficiently extract the main n-alkanes C27, C29, C31, and C33. A combined cleanup and fractionation approach on Teflon-coated silica SPE columns resulted in clean chromatograms and gave reproducible results (recoveries 90-95 %). The GC-MS method was reproducible (R(2) = 0.994-0.997, peak area standard deviation = 2-5%) and sensitive (LODs, S/N = 3, 0.05-0.15 ng/μL). The total main n-alkane concentrations were in the range of 5-50 μg/g dry weight. Seed extractions resulted in much lower total amounts of extracted n-alkanes compared to flesh and surface extractions, demonstrating the need for further improvement of pre-concentration and cleanup. The method was applied to 131 pepper samples from four different countries, and by using the relative n-alkane concentration ratios, Dutch peppers could be discriminated from those of the other countries, with the exception of peppers from the same cultivar. Graphical Abstract Procedure for pepper origin determination.
authors.affiliation: Mass Spectrometry of Biomacromolecules, Swammerdam Institute of Life Sciences (SILS), University of Amsterdam, Sciencepark 904, 1090 GE, Amsterdam, The Netherlands, e.derijke@uva.nl.
authors.forename: E
authors.initials: E
authors.lastname: de Rijke
authors.forename: C
authors.initials: C
authors.lastname: Fellner
authors.forename: J
authors.initials: J
authors.lastname: Westerveld
authors.forename: M
authors.initials: M
authors.lastname: Lopatka
authors.forename: C
authors.initials: C
authors.lastname: Cerli
authors.forename: K
authors.initials: K
authors.lastname: Kalbitz
authors.forename: C G
authors.initials: CG
authors.lastname: de Koster
mesh_terms: D000473:Alkanes / Q000032:analysis*; D002212:Capsicum / Q000737:chemistry* / Q000196:embryology; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D005843:Geography; D012639:Seeds / Q000737:chemistry*
chemical_list: D000473:Alkanes