Improving the productivity of a multidimensional chromatographic preparative system by collecting pure chemicals after each of three chromatographic dimensions

- The capability to collect volatiles in each dimension was demonstrated for a multidimensional preparative system.
- Two high-temperature valves were used in 1D and 2D between the Deans switch and FID to allow the collection of volatiles.
- The flow-resistance in the two positions of the valves were optimized to avoid retention time shifts after the valve operation.
- Highly pure sesquiterpene components were collected, namely patchouli alcohol after 1D, α-bulnesene after 2D and α-guaiene after 3D.

The enhanced sample collection capability of a heart-cutting three-dimensional GC-prep system is reported. In its original configuration, a highly pure component can be usually collected after the last (3D) column outlet by means of a dedicated preparative station. The latter is located after the last chromatographic column, and this poses the requirement for multiple heart cuts even for those components showing satisfactory degree of purity after the first (or second) separation dimension. The feasibility to collect pure components after each chromatographic dimension is here described, employing a three-dimension MDGC system equipped with high-temperature valves, located inside the first and second GC ovens, with the aim to improve the productivity of the collection procedure. In addition to a commercial preparative collector located at the 3D outlet, two laboratory-made collection systems were applied in the first and second dimension, reached by the effluent to be collected trough a high-temperature valve switching the heart-cut fraction between either the detector (FID), or the collector. Highly pure sesquiterpene components were collected, namely: patchouli alcohol after the first column [poly(5% diphenyl/95% dimethylsiloxane)], α-bulnesene after a second column coated with high molecular weight polyethylene glycol, and α-guaiene after an ionic-liquid based column (SLB-IL60), used as the third dimension. Purity levels ranging from 85 to 95% were achieved with an average collection recovery of 90% (n = 5). The following average amounts were collected per run: 160 μg for α-guaiene, 295 μg for α-bulnesene, and 496 μg for patchouli alcohol.