Separation of a Mixture of Pesticides by 2D‐TLC on Two‐Adsorbent‐Layer Multi‐K SC5 Plate

Abstract

A mixture of new pesticides admitted for marketing in Poland has been separated by use of two‐dimensional thin‐layer chromatography (2D‐TLC). The largest differences are obtained by combination of a normal‐phase (NP) system and a reversed‐phase (RP) system on a dual‐adsorbent layer containing a narrow zone of silica and adjacent to a wide zone of octadecyl silica (or vice versa). The greatest spread of points was obtained for the combination of nonaqueous NP phases with ethyl acetate–diisopropyl ether (2.5:97.5, v/v) on silica and RP phases, comprising a polar solvent (methanol or acetonitrile) in water on octadecyl silica adsorbent, which is wettable with water (RP‐18W). The correlations of R F values in NP/RP systems were utilized in the practical separation of a mixture of pesticides using 2D‐TLC on Multi‐K SC5 plate. The plates were scanned and videoscanned, showing the real pictures of TLC chromatograms.