Correlation of Retention Parameters of Pesti- cides in Normal and RP Systems and their Utilization for the Separation of a Mixture of Ten Urea Herbicides and Fungicides by Two-Dimensional TLC on Cyanopropyl-Bonded Polar Stationary Phase and Two-Adsorbent-Layer Multi-K Plate

Abstract

Ten urea herbicides and fungicides have been separated by use of two-dimensional thin-layer chromatography. The largest differences are obtained by combination of normal-phase (NP) system and reversed-phase (RP) system on cyanopropyl-bonded polar adsorbents and on two – adsorbent layer containing a narrow zone of octadecyl silica and adjacent a wide zone of silica (or vice versa). The greatest spread of points was obtained for combination of nonaqueous NP phases with ethyl acetate on silica and RP phases comprising a polar solvent (methanol) in water on octadecyl silica adsorbent wettable with water (RP-18W). A good spread of points was also obtained for pairs of normal-phase systems with heptane-ethyl acetate mobile phases and reversed-phase systems with water-dioxane mobile phases, both on thin layers of cyanopropyl-bonded polar adsorbents. The correlations of R F values in NP/RP systems were utilized in practical separation of a mixture of ten urea pesticides using 2D-TLC on these adsorbents. The plates were scanned and videoscanned showing the real pictures of TLC chromatograms.