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Equivalent chain lengths of all C4– C23 saturated monomethyl branched fatty acid methyl esters on methylsilicone OV-1 stationary phase
Ist Teil von
Journal of Chromatography A, 2011-04, Vol.1218 (13), p.1767-1774
Ort / Verlag
Amsterdam: Elsevier B.V
Erscheinungsjahr
2011
Link zum Volltext
Quelle
MEDLINE
Beschreibungen/Notizen
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.