Chromatographic separation open column, thin layer chromatography

Over the last two decades, HPLC has to a large extent superseded the classical modes of open column, thin-layer or paper chromatography previously used for natural product separation and has become an integral part of natural product analysis and preparative isolation. This can be attributed to various factors, including (1) availability of numerous chromatographic modes, robust high-resolution chromatographic materials and... 

Adsorption chromatographic separation can be carried out either in closed columns or open films the latter usually consists of a rectangular film of adsorbent supported on a glass plate. Chromatography on open films is referred to as thin-layer chromatography when the adsorbent particles adhere to each other and to the plate, and as loose-layer chromatography when the adsorbent particles are nonadherent. The combination... 

At the end of the 1930s, adsorption chromatography in columns as introduced by Tswett had become a powerful separation technique for plant extracts and natural products. Simultaneously, the need for a more rapid alternative suitable for identification of separated substances led to the invention of an open chromatographic system. In 1938, Izmailov and Shraiber reported the separation of belladonna alkaloids on a thin adsorbent layer, coated onto microscopic slides. Development of circular chromatograms was achieved by placing small amounts of various solvents to the center of samples previously applied as spots onto the layer. This method was an extremely rapid microtechnique requiring only small amounts of stationary and mobile phases. 

---