ABSTRACT
It is an astonishing sight when a 20 × 20 cm plate has tens or even hundreds of colorful spots. Its qualitative and quantitative evaluation may give useful information on the composition of the active ingredients in certain medications, on the pesticide contamination of soil sample, etc. As high-performance liquid chromatography (HPLC), capillary zone electrophoresis (CZE), and other
9.1 Introduction .......................................................................................................................... 147 9.2 Historical Overview .............................................................................................................. 148 9.3 Methodological Aspects ....................................................................................................... 149
9.3.1 Stationary Phases ...................................................................................................... 149 9.3.2 Chambers .................................................................................................................. 150 9.3.3 Stability Control ....................................................................................................... 151 9.3.4 Quantitative Evaluation ............................................................................................ 151
9.3.4.1 Computer Simulation of Continuous Development 2D-TLC .................... 152 9.3.5 Calculations .............................................................................................................. 152
9.3.5.1 Spot and Mobile-Phase Front Anomalies in Planar (Thin-Layer) Chromatography ........................................................................................ 155
9.3.6 Samples Subjected to 2D-TLC ................................................................................. 155 9.3.6.1 Natural Products, Plant Extracts ................................................................ 156 9.3.6.2 Lipids ......................................................................................................... 158 9.3.6.3 Steroids....................................................................................................... 158 9.3.6.4 DNA and DNA Damages ........................................................................... 159 9.3.6.5 Alkaloids .................................................................................................... 159 9.3.6.6 Antibiotics .................................................................................................. 159 9.3.6.7 Cations ....................................................................................................... 159 9.3.6.8 2D Elution-Displacement Chromatography .............................................. 159 9.3.6.9 Flip-Flop Chromatography ........................................................................ 159 9.3.6.10 Methyl β-Cyclodextrin in the Second Dimensional Development ............ 160
9.3.7 Argentation TLC....................................................................................................... 160 9.3.8 2D Elution-Displacement TLC ................................................................................ 160
9.3.8.1 2D Column Chromatography..................................................................... 160 9.3.8.2 Grafted Planar Chromatography ............................................................... 161 9.3.8.3 Section-Formed Development in the 2D-TLC ........................................... 161 9.3.8.4 2D Multiple Development .......................................................................... 162 9.3.8.5 Online Coupling of Liquid Chromatography with TLC ............................ 162 9.3.8.6 Ofine Coupling of TLC with Gas Chromatography ................................ 162
9.4 Discussion ............................................................................................................................. 162 Acknowledgments .......................................................................................................................... 162 References ...................................................................................................................................... 162
chromatographic procedures have progressed, so has planar chromatography. Sophisticated methods have been established for the development of the plates, for the quantitative evaluation of the separated spots, and also for the identication of the compounds by online UV-visible spectra, mass spectrometry (MS), and nuclear magnetic resonance spectroscopy, and the available information was further enhanced by 2D planar chromatography (2D-thin-layer chromatography [2D-TLC]).
