Planar chromatography analyte identification

In planar chromatography, reference compounds are chromatographed with the unloiown sample. Tentative identification is made by comparison of the migration distances and detection characteristics of the reference compounds with those of the unknown analytes. If the Rf of the unicnown analyte and the Rf of the reference compound do not match, the compounds are judged to be different. If they match, the compounds are presumed to be identical. However, as more than one compound can have the same Rf in a particular chromatographic system, the presumptive identification has to be confirmed by the use of specific spray reagents, antibody complexation, or isolation of the compound followed by chemical and/or instrumental analysis. Software is now available for compound identification by library searching of UV spectra based on corrected Rf values. ... 

The above overview on the present status of TLC as an analytical technique for pharmaceuticals and drugs stated that TLC covers a special range of analytical methods especially with newly introduced plates and identification techniques, as well as modem forced-flow methods. Planar chromatography does not compete with column liquid chromatography or gas chromatography. Instead, the three approaches are complementary and together provide for successful and rapid separation. In our opinion, TLC has and will probably always play a role in the analysis of pharmaceuticals and drugs. 

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