Luigi MondelloItaly

The collection of analytes from natural sources is the goal of each preparative system. Conventional GC analysis for preparative purpose presents different limitations when highly pure compounds have to be collected at milligrams level in a reasonable time. Although wide-bore columns (0.53 mm I.D.) are commonly used, providing an enhanced sample capacity, an excess of on-column sample amounts will result in skewed peaks and decreased resolution. On the other hand, the collection of pure components requires the injection of lower amounts in order to avoid co-elutions on the wide-bore column; as a consequence, the collection of highly pure components, at the milligram level, requires an increased total collection time. The higher is the injection volume, the lower is the total time required to collect a specific compound, thus the highest injection volume should be always used. Aiming to improve the productivity of the system a multidimensional prep-GC instrument is presented with the goal to reduce the total collection time and to improve the purity of the components collected.
To improve the capability of the system, an on-line 4D chromatographic system (prep LC-GC-GC-GC) instrument can be adopted enabling the injection of higher sample volumes from the separated HPLC components by exchanging the dirty sample matrix with a pure HPLC solvent containing the molecules of interest and acting as an additional automated sample preparation step.