Optimization of separation of (+)-catechin and (-)-epicatechin on cellulose TLC plates

The separation of (+)-catechin and (-)-epicatechin on cellulose TLC plates with 1-butanol-water-acetic acid, 4 + 2 + 1 (v/v), has been studied under different development conditions on prewashed and untreated TLC plates. Plates were developed in horizontal chambers (tank and sandwich configuration) and in twin trough (unsaturated and saturated) developing chambers. Tank configurations were used with and without preconditioning. Prewashing of the TLC plates, preconditioning, and the type of development chamber used had a large effect on the chromatographic results. Without prewashing of the TLC plate unsatisfactory or misleading results were obtained. Anisaldehyde-sulfuric acid dipping reagent proved to be more selective than vanillin-phosphoric acid as detection reagent for the detection of flavan-3-ols in oak bark extract; the latter was, however, more sensitive.