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Publisher Summary High performance thin layer chromatography (HPTLC) is faster and can be standardized much better in comparison to conventional TLC. This chapter discusses various spot application techniques and procedures for the direct photometric evaluation of HPTLC plates—reflectance, transmission, simultaneous reflectance and transmission, fluorescence quenching, and fluorescence. The efficiency of HPTLC is illustrated by practical examples and the most important requirements of a photometer employed for the quantitative evaluation of HPTLC plates are also discussed in the chapter. The HPTLC prefabricated plates exhibit a better chromatographic resolution, which is because of the carefully selected silica gel. Provided the diameter of the spots applied does not exceed 1.5 mm, the optimum of the chromatographic resolution is reached at a 3–5 cm migration of the solvent. The chapter also discusses the requirements of the instrument for the photometric evaluation of HPTLC chromatograms. Optimum signal depends on the photometric method, the amplification reserve of the photometer, and the electronic noise of the photometer. Optimum reproducibility depends on the photometric method, the precision of the mechanical system used for scanning, the electronic noise of the photometer, and spotting. |
