Chapter 5. Flat bed techniques

Abstract

This chapter discusses thin layer chromatography (TLC) and paper chromatography (PC), which together is composed of “flat-bed” or “planar” chromatography, are the easiest of all chromatographic methods to perform, and they require only simple and inexpensive equipment. Many of the techniques and principles of TLC and PC are the same. They both provide qualitative analytical information, and, with optimization of techniques and materials, can give quantitative data as well. An initial zone of mixture is placed near one end of the stationary phase, a thin layer or paper sheet; the sample is dried; and the end of the stationary phase with the initial zone is placed into a mobile phase, usually a mixture of pure solvents, inside a closed chamber. The components of the mixture migrate at different rates during the movement of the mobile phase through the stationary phase, which is termed the development of the chromatogram. When the mobile phase has moved an appropriate distance, the stationary phase is removed, the mobile phase is rapidly dried, and the zones are detected by application of a suitable visualization reagent. Sample collection, preservation and purification are common problems in both TLC and PC. Detection is most simple when the compounds of interest are naturally colored or fluorescent or absorb ultraviolet (UV) light.