Multidimensional gas chromatographic techniques

Gomera, B., Gonzalez, M.J. (2003). Enantiomeric separation of chiral PCBs in eggs of predatory birds from Donana National Park (Spain) by using multidimensional gas chromatographic techniques. Organohalogen Compounds 62, 273-276. 

Marriott PJ and Kinghom RM (2001) Multidimensional and comprehensive multidimensional gas chromatography. In Handley AJ and Adlard ER (eds.) Gas Chromatographic Techniques and Applications. Sheffield Sheffield Academic Press. 

The separation of the isomers of some environmental pollutants (chlor-danes, toxaphenes etc.) is a challenging job, while the chiral resolution of these pollutants is extremely difficult. A multidimensional gas chromatographic (MDcGC) approach for such types of chiral resolution of environmental pollutants has been proposed as the best choice. The MDcGC technique involves the use of two chiral columns of different polarities in series, each with a separate temperature control. The remarkable advantage of this technique, in both a qualitative and a quantitative sense, is a consequence of the fact that a valveless pneumatic system, which involves a live T-piece, allows a preselected small fraction to be cut from the eluate of the first column and transferred quantitatively and reproducibly to the second column. This technique may be used for the complete separation of chiral pollutants, with increased sensitivity and selectivity. Examples of this technique for the chiral resolution of environmental pollutants can be found in several publications [93-96, 122, 123]. 

W. Beitsch, Multidimensional gas chromatography , in Multidimensional Chromatography. Techniques and applications, H. J. Cortes (Ed.), Chromatographic Science Series, Vol. 50, Marcel Dekker, New York, pp. 74-144 (1990). 

Multidimensional gas chromatography has also been used in the qualitative analysis of contaminated environmental extracts by using spectral detection techniques Such as infrared (IR) spectroscopy and mass spectrometry (MS) (20). These techniques produce the most reliable identification only when they are dealing with pure substances this means that the chromatographic process should avoid overlapping of the peaks. 

If simple sample pretreatment procedures are insufficient to simplify the complex matrix often observed in process mixtures, multidimensional chromatography may be required. Manual fraction collection from one separation mode and re-injection into a second mode are impractical, so automatic collection and reinjection techniques are preferred. For example, a programmed temperature vaporizer has been used to transfer fractions of sterols such as cholesterol and stigmasterol from a reversed phase HPLC system to a gas chromatographic system.11 Interfacing gel permeation HPLC and supercritical fluid chromatography is useful for nonvolatile or thermally unstable analytes and was demonstrated to be extremely useful for separation of compounds such as pentaerythritol tetrastearate and a C36 hydrocarbon standard.12... 

A certain amount of qualitative information can be obtained by means of so-called multidimensional chromatography (1). Tlris is a combination of different chromatographic techniques in which fractions from a primary separation step are transferred online to a secondary separation step. Multidimensional gas chromatography (GC), for example, involves coupling of GC columns of different selectivities so that the primary column isolates the fraction of interest, and the secondary column takes care of the final separation of that fraction. Using multidimensional liquid chromatography (LC), determination of androgen hormone residues in cattle liver has been possible (2). 

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