Enantiomeric separation and analysis of unsaturated hydroperoxy fatty acids by chiral column chromatography-mass spectrometry

• Published in: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences Vol. 872; no. 1; pp. 90 - 98
• Main Authors: Garscha, Ulrike, Nilsson, Tomas, Oliw, Ernst H.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-09-2008; Elsevier Science
• Subjects: Analysis; Analytical, structural and metabolic biochemistry; Autoxidation; Biochemical Pharmacology; biokemisk farmakologi; Biological and medical sciences; Chromatography, High Pressure Liquid - methods; FARMACI; Fatty Acids, Unsaturated - analysis; Fatty Acids, Unsaturated - isolation & purification; Fundamental and applied biological sciences. Psychology; General pharmacology; Hydroperoxy eicosanoids; Hydroperoxy linoleic acids; Medical sciences; MS/MS fragmentation; Normal phase HPLC; Pharmacology. Drug treatments; PHARMACY; Photooxidation; Reprosil Chiral-NR; Spectrophotometry, Ultraviolet; Stereoisomerism; Tandem Mass Spectrometry; Autoxidation; Hydroperoxy linoleic acids; Reprosil Chiral-NR; Normal phase HPLC; Hydroperoxy eicosanoids; MS/MS fragmentation; Photooxidation; Enantioselectivity; Organic hydroperoxide; Polyunsaturated fatty acid; HPLC chromatography; Lipids; Chiral stationary phase; Linoleic acid; Normal phase chromatography; Optical resolution; Eicosanoid; Mass spectrometry MS/MS; Unsaturated fatty acid; Column chromatography; Mass spectrometry; Stationary phase
• ISSN: 1570-0232; 1873-376X; 1873-376X
• DOI: 10.1016/j.jchromb.2008.07.013

Hydroperoxides of 18:2n-6 and 20:4n-6 were obtained by autoxidation and photooxidation. The enantiomers were separated as free acids (Reprosil Chiral-NR column, eluted with hexane containing 1–1.2% alcoholic modifier) and analyzed by on line UV detection (234
nm) and liquid chromatography-MS/MS/MS of carboxylate anions (A
−
→
(A
−-18)
→
full scan) in an ion trap. The combination of UV and MS/MS/MS analysis facilitated identification of hydroperoxides even in complex mixtures of autoxidized or photooxidized fatty acids. The signal intensities increased about two orders of magnitude by raising the isolation width of A
− from 1.5
amu to 5 or 10
amu for
cis-trans conjugated hydroperoxy fatty acids, and one order of magnitude or more for non-conjugated hydroperoxy fatty acids. The
S enantiomer of 8-, 9-, 10-, and 13-hydroperoxyoctadecadienoic acids and the
S enantiomer of
cis-
trans conjugated hydroperoxyeicosatetraenoic acids eluted before the corresponding
R enantiomer with two exceptions (11-hydroperoxylinoleic acid and 8-hydroperoxyeicosa-5
Z,9
E,11
Z,14
Z-tetraenoic acid). The separation of enantiomers or regioisomers could be improved by the choice of either isopropanol or methanol as alcoholic modifier.