Comprehensive two-dimensional gas chromatography: a hyphenated method with strong coupling between the two dimensions.

Comprehensive two-dimensional gas chromatography (GC x GC) provides a true orthogonal separation system. It is explained and demonstrated that it generates a peak capacity that is approximately equal to the product of the peak capacities of the two individual separation systems. The resulting peaks are ordered in a two-dimensional plane in bands of compounds with the same characteristics. Quantitation of the separated (groups of) components is fundamentally not different from one-dimensional gas chromatography, but the sensitivity is far better and true baseline is always available. The two co-ordinates of each peak in the plane make the identification more reliable. Instrumental considerations of GC x GC are discussed. The three designs of contemporary GC x GC systems are presented and compared. Although the technique is still very young, a number of applications on complex samples as petroleum and environmental samples have already been reported. Finally, the future perspectives of GC x GC are discussed.