Silver ion high-performance liquid chromatography and gas chromatography—mass spectrometry in the analysis of complex fatty acid mixtures: application to marine invertebrates

Abstract

High-performance liquid chromatography on a stable silver ion column permitted the isolation of clean fractions differing in degree of unsaturation, with zero to six double bonds, of the methyl ester derivatives of fatty acids from complex lipid samples. By a combination of gas chromatographic analysis of the methyl esters on capillary columns coated with polar phases, and gas chromatography-mass spectrometry of the picolinyl ester derivatives, separated on non-polar phases, most components can be identified. In order to demonstrate the methodology, fatty acids from the Black Sea invertebrates Mytilus galloprovincialis and Rapana thomasiana were separated into 41 and 46 defined components, respectively (58 different fatty acids in total), and full quantitative analyses were achieved of most constituents present at levels of about 0.1% of the total and above. The fatty acids found included mono- and multi-methyl branched isomers, mono- and polyunsaturated fatty acids of the ( n-1), ( n-3), ( n-4), ( n-5), ( n-6), ( n-7), ( n-8), ( n-9), ( n-11) and ( n-13) families, and dienoic acids with several methylene groups between the double bonds, ranging in chain length from C 13 to C 22.