Comprehensive Two-Dimensional Gas Chromatography using an On-Column Thermal Modulator Interface

A thermal desorption modulator prepared on an open-tubular gas chromatographic column continuously generates fast chromatograms sampled from a flowing stream. The output from a slower chromatographic column is a suitable sample stream. Taking the output from one gas chromatographic column as input to a second column through a thermal modulator then generates a set of high-speed chromatograms. One such secondary chromatogram is generated at each point in the primary chromatogram. When plotted in an appropriate two-dimensional form, this set of high-speed chromatograms becomes a comprehensive two-dimensional gas chromatogram. A sample first separated by one column is separated a second time by an independent column. All substances in the sample mixture pass through both columns. Two retention time measures characterize each sample substance. Each substance forms a peak on the two-dimensional plane at a location determined by the interaction of the substance with the two different stationary phases.