HPLC chromatography system / UV / compact
The CAMAG Automated Multiple Development procedure allows thin-layer chromatography to be utilized for tasks that could not be performed by TLC in the past.
Only the AMD 2 procedure can be successfully employed for reproducible gradient elution with silica gel as the stationary phase. In column liquid chromatography, gradient elution is common on reversed phases only because a silica gel column would call for a time consuming reconditioning or be irreversibly degraded, which is not acceptable in a technique depending on multiple use of the stationary phase. In Thin-Layer chromatography this is not relevant.
The principle of the CAMAG AMD procudure
The HPTLC plate is developed repeatedly in the same direction.
Each successive run extends over a longer solvent migration distance than the one before.
Between runs, the solvent is completely removed from the developing chamber and the layer is dried under vacuum.
Each successive run uses a solvent of lower elution strength than that of the one used before. In this way, a stepwise elution gradient is formed.
The combination of focusing effect and gradient elution results in extremely narrow bands. Their typical peak width is about 1 mm. This means that, with the available separation distance of 80 mm, up to 40 components can be completely resolved, i.e. with base line separation.