New approaches in TLC-densitometry

The use of a TLC scanner can be regarded as a key step in high performance thin layer chromatography (HPTLC). Densitometric measurements transform the substance distribution on a TLC plate into digital computer data. Systems that allow quantitative measurements have been available for many years for either fluorescence or ultraviolet absorption measurements, while lately the reflection analysis mode for both types is the most common application. New scanning approaches are designed to aid the analyst who has common demands for TLC-densitometry without using special data, such as scanned images. Two examples that have been developed lately in the laboratories of the authors are described in this paper. These approaches were developed on the basis of current needs for analysts who employ TLC as a tool in research, as well as in routine analysis. One approach is aimed to support analysts in economically disadvantaged areas, where cost intensive apparatus is unsuitable but trace analysis by simple means is required. The other system, allows the spectral determination of chromatographic spots on TLC plates covering the ultraviolet and visible range, thus, revealing highly desired information for the analyst