Single column chromatographic procedures are widely applied in the analysis of complex matrices. Although such approaches often provide satisfactory results, the complexity of many samples exceeds the separative capacity of any monodimensional system.

A typical comprehensive analysis is achieved, generally, on two independent columns connected by means of a special transfer system located between them. The type of interface used is linked to the specific methodology (comprehensive GC, comprehensive LC, etc.). The function of the transfer system is to isolate and then �inject� continuous primary column fractions onto a fast second dimension. In order to achieve comprehensive analysis and to preserve the 1D resolution, the bands injected onto the secondary column must undergo elution before the following 2D analysis. During the development of each 2D separation, the interface is engaged in the following isolation process.

Various comprehensive chromatographic applications on different natural matrices will be presented. LC x LC applications will regard the development of a MD normal-phase (NP)- reversed-phase (RP)- HPLC system. Also in this case, the relative location of the components in the 2D plane is correlated to the chemical structure of the components, and allows positive identification. The contribution is focused on the most advanced multidimensional chromatographic techniques today employed. A series of applications on different samples will be described in order to demonstrate the effectiveness of these approaches.