Application of selective ion monitoring to the analysis of molecular species of vegetable oil triacylglycerols separated by open‐tubular column GLC on a methylphenylsilicone phase at high temperature

Analyses of the molecular species of authentic triacylglycerols and of soybean triacylglycerols, which were separated on a fused silica open‐tubular column coated with a methylphenylsilicone gum stationary phase, were carried out by selective ion monitoring mass spectrometry. It was determined that peak assignments could be made by selecting certain characteristic ions with the same retention time on the SIM profile, that is, three ions of the type RCO+ corresponding to the fatty acyl residues (R1CO+, R2CO+ and R3CO+) and the corresponding three M‐acyl ions ([M‐OCOR1]+, [M‐OCOR2]+ and [M‐OCOR3]+ instead of the molecular ion. The yield of [RCO‐1]+ and [RCO‐2]+ and relating these to the unsaturated fatty acyl residues is inconvenient for an exact peak assignment. The SIM method was further applied to the peak assignment of the triacylglycerols from palm, cottonseed and safflower oils and certain new fatty acid combinations are proposed.