Polarity changes during capillary gas chromatographic and gas chromatographic mass spectrometric analysis using serially coupled columns of different natures and temperature programming - Application to the identification of constituents of essential oils

The polarity and characteristics of systems obtained by connecting two capillary gas chromatography columns of different polarities in series using temperature programming has been determined both in gas chromatography and gas chromatography-mass spectrometry analysis. The influence of the relative length of the two columns and of the column sequence (more polar in front, less polar at the end or the reverse) has been studied. In order to test this method on real world samples, the behavior of different configurations towards a synthetic mixture of nineteen constituents found in essential oils, thirteen of which are not separated on a single column, has been tested. On the best configurations (polar column in front followed by the non-polar one), all of the compounds of the test mixture gave well separated chromatographic peaks. The technique of using capillary gas chromatography columns of decreasing polarity, coupled in series, works efficiently using classical temperature programming from room temperature to the limits of the column used. Therefore, this method is ideally suited for the separation and identification of multicomponent complex mixtures in gas chromatography (or gas chromatography-mass spectrometry). (C) 1998 Elsevier Science B.V. All rights reserved.