Comprehensive two-dimensional liquid chromatography×gas chromatography: evaluation of the applicability for the analysis of edible oils and fats

Edible fats and oils are complex mixtures containing a wide range of (classes of) compounds. The most important group of compounds are the triglycerides (triacylglycerides, TAGs). Because of the large number of possible fatty acid combinations, an enormous number of TAGs is possible. In the present feasibility study, the applicability of different modes of comprehensive two-dimensional LC×GC for detailed oil and fat analysis is evaluated. Comprehensive LC×GC was found to be an extremely powerful analytical method for the analysis of complex TAG samples. Using the new comprehensive set-ups, TAGs can be separated according to two independent parameters: carbon number vs. number of double bonds, or fatty acid composition vs. number of double bonds. The information content of comprehensive separations by far exceeds that of the current generation of analytical methods. The quantitative results of the separations show a good agreement with data obtained from standard analytical methods. The comprehensive methods studied can also be used for fingerprinting of oil samples, as well as for the analysis of target compounds or compound groups. Highly detailed separations of olive oil samples were obtained. Zooming in on one region of the chromatogram allowed reliable analysis of wax esters without interferences of sterol esters.