title: Equivalent chain lengths of all C4-C23 saturated monomethyl branched fatty acid methyl esters on methylsilicone OV-1 stationary phase.
abstract: Isomer mixtures of monomethyl branched saturated C7-C23 fatty acid methyl esters (FAME) were prepared by performing a methylene insertion reaction to the straight chain FAME and this study model was completed by using commercially available standards of C4-C7 FAME. The equivalent chain lengths (ECL) of all 220 C4-C23 monomethyl branched FAME on OV-1 stationary phase were measured, achieving an average repeatability of ±0.0004 ECL units. The monomethyl branched FAME was identified by GC on the basis of regularity of the fractional chain lengths (FCL) dependence on the number of carbon atoms (C(z)) of individual homologous series of methyl 2-, 3-, …, 21-FAME. The prediction of retention of the first homologues, having the new position of methyl group beginning at higher carbon atoms number, and analogously for the second, third, fourth, and other members of the homologous series, allowed the dependence FCL=f(C(z)) for the first and subsequent members of beginning homologous of monomethyl derivatives of FAME. The identification was confirmed by mass spectrometry. All of the methyl isomers of FAME, which could not be completely separated by gas chromatography due to having a methyl group in surroundings of the middle of the carbon chain, were resolved by mass spectrometry using deconvolution in a SIM-mode. Measured gas chromatographic and mass spectrometric data were applied for identification of the monomethyl branched saturated FAME in tongue coating.
authors.affiliation: Institute of Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina CH-2, Bratislava, Slovakia. kubinec@fns.uniba.sk
authors.forename: Róbert
authors.initials: R
authors.lastname: Kubinec
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Blaško
authors.forename: Renáta
authors.initials: R
authors.lastname: Górová
authors.forename: Gabriela
authors.initials: G
authors.lastname: Addová
authors.forename: Ivan
authors.initials: I
authors.lastname: Ostrovský
authors.forename: Anton
authors.initials: A
authors.lastname: Amann
authors.forename: Ladislav
authors.initials: L
authors.lastname: Soják
mesh_terms: D015415:Biomarkers / Q000032:analysis / Q000737:chemistry; D005227:Fatty Acids / Q000032:analysis / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D015394:Molecular Structure; D012828:Silicones / Q000737:chemistry; D014059:Tongue / Q000737:chemistry
chemical_list: D015415:Biomarkers; D005227:Fatty Acids; D012828:Silicones