Selection or removal of compounds from complex samples by peak isolation using an enhanced GCxGC configuration

We developed a novel approach to isolate and recollect or remove nearly any compound from complex GCxGC chromatograms. This was achieved by modifying a thermal desorption-GCxGC-Q-TOF system with a Deans switch, a passive splitter, and careful optimization of flows and capillary dimensions. The setup was evaluated with 106 standard chemicals covering a wide range of volatility (boiling points: 56 – 343 ⁰C) and polarity (log P: -0.2 – 9.4). We found that the recovery from tube to tube can become highly efficient if a custom-made adapter is attached directly on the flame ionization detector port (average recovery rate of 76 ± 7%). Furthermore, we were able to isolate peaks separated by a minimum distance of 50 milliseconds from each other at the base throughout the whole chromatographic run. In addition, the setup was designed for easy adaptation by repurposing existing instrument control software to define the isolation windows for the compounds of interest (first and second column retention time windows). We expect this novel development to allow several new applications, e.g., the isolation and selective enrichment or removal of molecules in food and flavour analysis; the investigation of suspect chemicals (incl. unknowns) for effect directed analysis (e.g., bioassays), and the isolation of compounds in the high-ng range (upon multiple isolation iterations) to be subjected to further chemical analyses (e.g. chemical ionization tandem mass spectrometry).