Over-pressure TLC

Over-pressure TLC (OPTLC) was introduced by Tyihak et al. in 1979 (13) m an attempt to combine the advantages of conventional TLC and HPLC. This technique employs the use of a pressurized circular ultra microchamber (PUM chamber), which houses a TLC plate and inlets for the introduction of sample and solvent onto the sorbent. The thin sorbent layer is covered by a membrane kept under external pressure so that the vapor phase above the sorbent is nearly eliminated. A substantially shorter time is required for separation than in conventional TLC and classical column chromatography (CC) and greater resolution and separation efficiency is achieved. The rate at which solvent migrates IS as stable as HPLC and consequently the technique can be used to model CC... 

Thin-layer gel chromatography (TL GPC) is a technique utilizing the flat bed of gel supported by a plate of glass, metal or plastics. The experimental arrangement of TL GPC is similar to conventional thin-layer chromatography, but since the wet gel beds are most often used, gravitation is employed for the generation of flow instead of capillary elevation. Evidently, the procedures of over-pressurized TLC may also be applied. 

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