Premium
Simultaneous determination by GC‐MS of epoxy and hydroxy FA as their methoxy derivatives
Author(s) -
Wilson R.,
Lyall K.
Publication year - 2002
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-002-0980-5
Subject(s) - epoxy , chemistry , saponification , tetramethylammonium hydroxide , derivatization , boron trifluoride , chromatography , fatty acid methyl ester , linoleic acid , methanol , organic chemistry , fatty acid , mass spectrometry , catalysis , biodiesel
We report on a capillary GC‐MS method for the quantitative analysis of hydroxy and epoxy FA. Catalytic hydrogenation of lipid extracts produces stable saturated lipids. Saponification followed by methylation with boron trifluoride in the presence of methanol converts FA to methyl esters and epoxy groups to methoxy‐hydroxy groups. These compounds are purified from nonoxidized methyl esters using solid phase extraction. Derivatization of the hydroxy group using tetramethylammonium hydroxide forms methoxy and vicinal dimethoxy FAME. When subjected to El‐MS, fragmentation gives two characteristic ion fragments for each epoxy and hydroxy positional isomer. Quantitative measurements were achieved using uniformly labeled hydroxy and epoxy 13 C FA as internal standards. Epoxy and hydroxy FA were identified in both plasma and adipose tissue of men, and the levels of hydroxy and epoxy in these tissues were related. The levels of hydroxy isomers were typical of oxidation of linoleic acid, whereas epoxy isomers were characteristic of oxidation of oleic acid.