Opportunities for ultra-high resolution analysis of essential oils using comprehensive two-dimensional gas chromatography: a review

In comprehensive 2D gas chromatography, the entire sample is simultaneously subjected to analysis on two capillary columns. By using a suitable modulation interface between the primary and secondary columns, hundreds of fast, second-dimension chromatograms are produced. The data from these chromatograms are treated such that a 3D surface plot or a 2D contour plot of the components' individual retention times, on each column, as well as peak responses, are represented. In a properly tuned comprehensive 2D chromatogram, the individual sample components are spread throughout a 2D separation space, providing a significant increase in the probability of resolving a greater number of sample components without increasing the analysis time. Comprehensive 2D-GC has proved useful for high-resolution conventional essential oil analysis as well as high-resolution enantioselective essential oil analysis. Combining comprehensive 2D-GC with either a quadrupole or time-of-flight mass spectrometer gives a powerful 3D analysis technique, which is extremely effective for complex sample analysis. The present status and opportunities arising from these ultra-high resolution approaches are discussed herein.