Monoepoxy octadecadienoates and monoepoxy octadecatrienoates 2: mass spectral characterization

摘要

Methyl esters of C18 Polyunsaturated fatty acids, including gamma-linolenic acid, u-Iinolenic acid and stearidonic acid, were epoxidised using m-chloroperbenzoic acid. Nine monoepoxides were obtained by normal-phase HPLC, identified using LC-MS and NMR, and characterized by NMR spectroscopy and mass spectrometry. This study is focused on structural characterization using LC-MS and LC/APCI/MS/MS. The elution profiles of these monoepoxides in RP-HPLC are determined as 12,13-> 9,10-> 6,7-epoxy, 9,10-> 15,16-> 12,13-epoxy and 15,16-> 12,13-> 9,10-epoxy derivatives of gamma-linolenic, alpha-linolenic and stearidonic acid methyl esters, respectively. The major diagnostic fragmentations in MS/MS identified are postulated to be induced by cleavages of the epoxide ring and alpha-bond cleavage to the epoxy group from [M+H](+) and/or [M+H-MeOH](+). (c) 2008 Elsevier Ireland Ltd. All rights reserved.