Multidimensional gas chromatography–infrared spectrometry–mass spectrometry. Plenary lecture

Abstract

Multidimensional gas chromatography coupled with multispectral detection was investigated for the analysis of complex mixtures. As a test of this new methodology, the essential oil of cascarilla bark was analysed by capillary gas chromatography using a combination of mass spectral and both vapour phase and matrix isolation infrared spectral detection. The separation of components in this complex essential oil was carried out using a multidimensional capillary gas chromatography system with parallel cryogenic traps interposed between the first and second separation stages. By employing a multiport valve and multiple traps, it was possible to analyse multiple heartcuts from a single first-stage separation or, alternatively, to concentrate minor components by means of multiple-injection procedures. It was also possible to perform iterative heartcut analysis employing multiple analytical columns with different polarities by sample looping. The instrumentation developed provides flexibility in choice of trapping-time intervals in order to improve dynamic range, reduces experimental time relative to that required with a single cryogenic trap, and facilitates parallel enrichment of minor components in different chromatographic segments. This separation strategy combined with three different modes of spectrometric detection facilitates comprehensive analysis of a complex mixture. In this study, vapour phase and matrix isolation infrared spectral analyses were compared, the advantages of parallel analytical columns for complex mixture analysis were assessed, and a method to fingerprint essential oils by enrichment of minor components was investigated.