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

The enhanced sample collection capability of a heart-cutting three-dimensional GC-prep system isreported. 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 chro-matographic column, and this poses the requirement for multiple heart cuts even for those componentsshowing satisfactory degree of purity after the first (or second) separation dimension. The feasibility tocollect 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 GCovens, with the aim to improve the productivity of the collection procedure. In addition to a commercialpreparative collector located at the 3D outlet, two laboratory-made collection systems were applied inthe first and second dimension, reached by the effluent to be collected trough a high-temperature valveswitching the heart-cut fraction between either the detector (FID), or the collector. Highly pure sesquiter-pene components were collected, namely: patchouli alcohol after the first column [poly(5% diphenyl/95%dimethylsiloxane)], alfa-bulnesene after a second column coated with high molecular weight polyethyleneglycol, and alfa-guaiene after an ionic-liquid based column (SLB-IL60), used as the third dimension. Puritylevels ranging from 85 to 95% were achieved with an average collection recovery of 90% (n = 5). Thefollowing average amounts were collected per run: 160 ug for alfa-guaiene, 295 ug for alfa-bulnesene, and 496 ug for patchouli alcohol.