Progress in forced-flow planar chromatography.
This paper summarizes progress in forced-flow planar chromatography (FFPC) and demonstrates the importance of the different techniques like rotation planar chromatography (RPC), overpressured-layer chromatography (OPLC), and electroplanar chromatography (EPC). Special attention is paid to a novel analytical FFPC method in which continuous development and continuous evaporation of the mobile phase from the end of the chromatographic plate ensure forced-flow development. A simple, but powerful preparative forced-flow technique is also reported; in this technique hydrostatic pressure is used to increase mobile-phase velocity. Parallel- and serially coupled layers open up new vistas for the analysis of a large number of samples (up to 216) for high throughput screening and for the analysis of very complex matrices. The special features of fully off-line and fully on-line RPC, OPLC, and EPC are compared in a table. New detection methods--on-line coupling of OPLC with radiodetection and on-line OPLC-MS--are also discussed. The role of a new spraying device for post-chromatographic chemical detection and for biological detection is also discussed. Some applications, relating to different classes of substances, are given to demonstrate the versatility of the various FFPC techniques.