Comprehensive two-dimensional gas chromatography under high outlet pressure conditions: A new approach to correct the flow-mismatch issue in the two dimensions

• Restrictors are successfully prepared directly at the outlet of a GC × GC column set.
• At elevated outlet pressures the flow mismatch in GC × GC is reduced.
• Operation of GC × GC at elevated outlet pressures improves the overall peak capacity.
• GC × GC with restrictor is suitable for complex multidimensional separations.

The typical column sets employed in comprehensive two-dimensional gas chromatography (GC × GC) suffer from the impossibility to fully exploit the efficiency of both dimensions simultaneously. Adding a restrictor at the end of the second dimension is a possible approach to adjust the linear velocity profile. Under these high outlet pressure conditions the second dimension becomes much slower while the effect on the primary column is limited. The gap in terms of optimum inlet pressures is thus reduced. A program written in Microsoft Excel® was used to calculate the efficiencies of the two dimensions in GC × GC at different outlet pressures. A GC × GC set-up with a restrictor at the end of the second dimension column was successfully installed. Experiments proved that this is a possible way to have a better exploitation of the columns. The chromatograms obtained for a number of applications confirm that the separations achieved at elevated outlet pressure are more efficient than those obtained with the same column set under atmospheric outlet conditions. The price to pay is that the separations become considerably slower.