Special Column Chromatography

Abstract

Conventional open-column chromatography is universally practised as a result of its simplicity of operation. If silica gel is the support, 30 mg sample loadings per g of 50–200 µm support are feasible (Verzele and Geeraert 1980) but this very high capacity is only possible when the substances to be separated differ greatly in their R_f values. Loadings of 10 mg sample per g of support are more common. Alternatively, in the filtration mode, silica gel chromatography can be performed under overloaded conditions, e.g. in the filtration of hydrocarbon terpenes and oxidized terpenes from essential oils (Verzele and Geeraert 1980), where 1 g of essential oil can be applied per 10 g of silica gel. Deactivation of the silica gel sorbent may be necessary to avoid decomposition of the sample on the column (e.g. Bruno et al. 1996).