Comprehensive two-dimensional gas chromatography via differential flow modulation

A novel comprehensive two-dimensional gas chromatograph has been developed that utilizes differential flow modulation. This technique uses a 6-port valve to collect effluent from a primary column and periodically inject the effluent into a secondary column. The flow in the secondary column is kept 20 times larger than the flow in the primary column so the contents of the sample loop can be flushed into the secondary column in 5% of the collection time. Peaks widths at half-maximum of approximately 0.06 s are generated for a 1.0 Hz secondary injection frequency. Sensitivity is not compromised, as 80% of the sample passes through both columns and reaches the detector. This simple yet effective technique has been used to analyze mixtures of alkanes, alkenes, aldehydes, alcohols, aromatics, esters, and ketones with high speed and high resolution.