Liquid chromatography—mass spectrometry of hydroxy and non-hydroxy fatty acids as amide derivatives

Abstract

A useful method for analyzing fatty acids by liquid chromatography—mass spectrometry with an atmospheric-pressure chemical-ionization interface system has been developed. The sensitivity of six kinds of palmitamide derivatives monitored by a single ion of [M + H] + was, in decreasing order: N- n-propylamide > anilide > N,N-diethylamide, amide > N,N-diphenylamide > N-1-naphthylamide. Individual fatty acids were identified from a mixture of amide derivatives of authentic fatty acids from C 16:0 to C 30:0 on a mass chromatogram. This method was used to detect both hydroxy and non-hydroxy fatty acids. Many kinds of fatty acid, including hydroxy fatty acids of the rat brain, were detected in a single run.