Gradient elution in Thin-Layer Chromatography
AMD = Automated Multiple Development
Only the AMD 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 procedure
Key features of the AMD 2 at a glance: