Comprehensive Two-Dimensional Gas Chromatography for Detailed Characterisation of Petroleum Products

Comprehensive two-dimensional gas chromatography (GC×GC) is a major advance for the detailed characterisation of petroleum products. This technique is based on two orthogonal dimensions of separation achieved by two chromatographic capillary columns of different chemistries and selectivities. High-frequency sampling between the two columns is achieved by a modulator, ensuring that the whole sample is transferred and analysed continuously in both separations. Thus, the peak capacity and the resoluting power dramatically increase. Besides, highly structured 2D chromatograms are obtained upon the volatility and the polarity of the solute to provide more accurate molecular identification of hydrocarbons. In this paper fundamental and practical considerations for implementation of GC×GC are reviewed. Selected applications obtained using a prototype of a GC×GC chromatograph developed in-house highlight the potential of the technique for molecular characterisation of middle distillates, sulphur speciation in diesel and analysis of effluents from petrochemical processes.