Enantiomeric composition of selected chiral compounds present in complex mixtures is determined by using the online coupling of reversed-phase liquid chromatography (LC) to gas chromatography (GC) and mass spectrometry. Integration of sample preparation into GC analysis, in a completely automated way, is achieved by means of the effective clean-up resulting from both the LC fractionation step and the eluent elimination provided by the through oven transfer adsorption desorption system used for LC-GC interfacing. The possibilities of the technique are illustrated through some examples concerning the stereodifferentiation in essential oils of major and minor chiral compounds via LC-GC transfer of different volume fractions, ranging from 0.5 to 1.9 ml, which show the significance of the window size for the determination of enantiomeric profiles.
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