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In the 1960s, the development of an ultramicro (UM) layer liquid chromatographic (LLC) separation chamber brought about a special combination of the two basic liquid chromatographic (LC) techniques, column LC and LLC. In this simple chamber the adsorbent layer of the chromatoplate was covered by a glass plate and/or plastic film during the separation process such that the end of the cover plate was not immersed in the mobile phase (eluent). Elimination of the vapor phase above the adsorbent layer in LLC was first achieved by use of this UM chamber. Further possibilities of this type of closed-layer chamber—for example, the use of a pumping system to increase and optimize the flow velocity through an optional development distance and the use of a special chromatographic plate—were subsequently realized by the development of an experimental pressurized UM (PUM) chamber. In this unique solution an external pressure is applied to the surface of the adsorbent layer by means of a cushion, forcing the mobile phase to flow (by overpressure) through the adsorbent layer as in HPLC. The PUM chamber is the basic instrument in so-called overpressured-layer chromatography (OPLC). The first commercially available OPLC instrument (Chrompres 10) was a completely off-line system. The second generation instrument (Chrompres 25) was suitable for both off-line and on-line separations. However, these conventional OPLC instruments and methodological solutions were suitable in general for of the advantages of OPLC versions over TLC and HPTLC in analytical and preparative separations. A new automated microprocessor-controlled separation system, new technology in the field of LLC, ensures rapid, efficient, and reproducible off-line and on-line isocratic and stepwise gradient separations. These technological solutions have opened new horizons in the field of LLC and exploit more attractively the advantages of layer liquid systems. This chapter summarizes the latest results obtained with conventional and modern OPLC versions. (The positive results of the BioArena system are demonstrated in Chapter 7 in this book.) |
