Application of selected ion monitoring to the analysis of triacylglycerols in olive oil by high temperature-gas chromatography/mass spectrometry.

The analysis of the triacylglycerol (TAG) composition of oils is a very challenging task, since the TAGs have very similar physico-chemical properties. In this work, a high temperature-gas chromatographic method coupled to electron ionization-mass spectrometry (HT-GC/EI-MS), in the Selected Ion Monitoring (SIM) mode, method was developed for the analysis of TAGs in the olive oil; this is a method suitable for routine analysis. This method was developed using commercially available standard TAGs. The TAGs studied were separated according to their equivalent carbon number and degree of unsaturation. The peak assignment was carried out by locating the characteristic fragment ions having the same retention time on the SIM profile such as RCO+74 and RCO+128 ions, due to the fatty acyl residues on sn-1, sn-2 and sn-3 positions of the TAG molecule and the M-OCOR ions corresponding to the acyl ions. The developed method was very useful to eliminate the interferences that appeared in the mass spectrum since electron ionization can prevent satisfactory interpretation of spectra.