Differences in Chromatographic Properties of Fused Silica Capillary Columns, Coated, Crosslinked, Bonded, or Crosslinked and Bonded with Polyethylene Glycols (Carbowax 20M) Using Complex Fatty Acid Methyl Ester Mixtures

Separations of fatty acid methyl esters were compared using four fused silica capillary columns which were either coated, crosslinked, bonded, or bonded and crosslinked with polyethylene glycols (Carbowax® 20M). Bonding and crosslinking did affect the polarity of the stationary phase, contrary to the claim of the manufacturer. The separation sequence of a number of polyunsaturated fatty acid methyl esters changed sufficiently to resolve some overlapping pairs and invert the relative emergence of other fatty acid methyl esters. It appears that the bonded or bonded and crosslinked polyethylene glycol phases, with their slightly increased polarity, gave superior separations in addition to greater stability compared to the coated Carbowax 20M column.