Column selection approach to achieve a high peak capacity in comprehensive three-dimensional gas chromatography

The separation power of comprehensive three-dimensional gas chromatography (GC³) is substantially enhanced through proper selection of the phase volume ratio, β, of each column relative to each other on successive dimensions. Consideration and application of the ratio of phase volume ratios, β_r, or β ratio, between successive dimensions has been a relatively un-studied approach to maximize separating power in comprehensive multidimensional GC instrument design. Herein, proper selection of β_r in multidimensional GC is shown to control the elution temperature, T_e, of analytes throughout a 40 min primary (¹D) column separation, and thus better control width-at-base, W, on all three dimensions. Specifically, between the ¹D and secondary (²D) columns, a β_r of 0.45 was applied, and between the ²D and tertiary (³D) columns a β_r of 1.0 was applied. A total ideal peak capacity of 30,600, or a peak capacity production of ~770 peaks/min, was accomplished with the GC³ instrument with the reconfigured parameters. Additionally, due to the complex nature of this three-dimensional data, a novel approach to "slicing" the chromatographic run into user-defined time intervals is shown. This novel way to view the data still elicits a traditional GC×GC chromatograms, but with the focus on ²D × ³D separations. Moreover, due to proper β_r selection, every 2 s window (i.e. every ¹D modulation period) is shown to have a peak capacity of ~50-100 for each ²D × ³D separation. This high overall peak capacity (30,600) and peak capacity per ¹D modulation (~50-100), courtesy of proper column selection, is demonstrated to hold great promise to physically separate truly complex mixtures.