Comprehensive Two-dimensional Gas Chromatography / Time of flight-mass Spectrometry (GC×GC/TOF-MS) and Its Application in Analysis of Complex samples

Many analytical problems require more resolution than a single chromatographic technique can provide. In such cases the separation power can be enhanced by using more than one separation technique or mechanism. The sample is then dispersed in different time dimensions. The resolution obtained depends strongly on the difference between these dimensions. The highest resolution is gained when there is no correlation between the separations, the dimensions being orthogonal to each other. Comprehensive two-dimensional gas chromatography (GCxGC) provides a true orthogonal separation system in which a modulator serially couples two columns containing dissimilar stationary phases, it focuses and subsequently reinjects components eluting from the first into the Second column. The system generates a peak capacity that is approximately equal to the product of the peak capacities of the two individual separation systems. In this paper, technique and instrumental considerations of GCxGC are discussed. The designs of contemporary GCxGC systems are presented and compared. A number of typical applications on complex samples as traditional chinese medicines, cigarette smoking, petroleum and environmental samples are also cited. As a comparison, HPLCxHPLC is also presented.