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

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