Evaluation of porous graphitic carbon as stationary phase for the analysis of fatty acid methyl esters by liquid chromatography

Polyunsaturated fatty acids have been analysed as methyl esters by liquid chromatography on porous graphitic carbon and the results compared with those obtained on octadecyl bonded phases. Chromatographic behaviour on octadecyl bonded phases arises principally as a result of hydrophobic interactions with the bonded phase. Because the retention of analytes is greater on porous graphitic carbon than on octadecyl phases, organic mobile phases are required. When the number of double bonds is low (ca 1-3), the behaviour of porous graphitic carbon is similar to that of octadecyl bonded phases, but when this number increases stronger interactions with the flat surface of the graphite appear, resulting in new selectivity. These two 'reversed-phase' systems are considered complementary for separation of different fatty acid methyl esters, An additional advantage of porous graphitic carbon is that it enables isolation of hexadecatrienoic and hexadecadienoic acids, which are not available commercially.