Chromatographia 58 (11-12), 781-788 (2003). 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 systems with ethyl acetate on silica and RP systems 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 cyanopropyl-bonded polar adsorbents. The correlations of Rf 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.

J. Planar Chromatogr. 22, 235-240 (2009). HPTLC of pesticides (clofentezine, neburon, chlorfenvinphos, lenacyl, trifluralin, thiram, procymidone, flufenoxuron, tralkoxydim, propaquizafop, dinoseb) and water samples (sample preparation by solid phase extraction) on silica gel with ethyl acetate - n-heptane 1:4 and 3:7 in a horizontal chamber. Quantitative determination by diode array densitometry in the range of 200 to 600 nm. The limit of detection was between 40 and 650 ng/spot and the limit of quantification was between 120 and 1920 ng/spot.

J. Agric. Food Chem. 35, 100-1 05 (1987). Analytical and preparative TLC separation of fenvalerate and metabolites on silica 60 F 254 in one- and two-dimensional modes with 7 different solvent systems, e.g. hexane - toluene - acetic acid 3:15:2 and toluene - ether 10:1.

Chinese Anal. Chem. (Fenxi Huaxue) 20, 800-802 (1992). TLC of 2,2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane isomers on silica with 10% ether in pentane. Quantification by densitometry at 245 nm.

Asian Journal of Chemistry 23(5), 2011-2013 (2011). Methods are reported for determination of organophosphorus pesticides using TLC-cholinesterase inhibition as well as GC-FID. The powdered rice sample was initially extracted with ethyl acetate. The extract was cleaned up by GPC, eluted with cyclohexane - ethyl acetate 1:1, evaporated, and taken up in acetone. This extract was analysed by TLC on silica gel with ethyl acetate to a developing distance of 10-12 cm. After development the plate was air dried, exposed to bromine vapors, sprayed with enzyme solution and incubated at 37 °C for 30 min and sprayed with the reagent. White spots appeared against bluish-red background. The sample was also analysed by GC and the GC method was very sensitive. However, the TLC method is recommended for preliminary screening of samples.

Acta Alimentaria 16, 29-43 (1967). Twenty-one identified strains of fusarium sp. were examined for their ability to produce F-2 and T-2 toxin on sterilized, moistened rice and corn grains. The F-2 and T-2 toxin production was estimated by TLC and confirmed by GLC. TLC of F-2 toxin on silica with toluene - ethyl acetate - chloroform 95:55:50 and chloroform - acetone 97:3; after development plates heated for 5 min. at 120 °C, detection of zearalenone by UV 366 and 254 nm. Detection of F-2 toxin by spraying with 1 % 4-methoxy - benzene - diazonium- fluoroborate and heating for 10 min at 110 °C. Sensitivity: 0.03 mg/spot. TLC of T-2 toxin on silica with toluene - ethyl acetate - 90 % formic acid 6:3:1; spraying with 20 % sulfuric acid in 96 % ethanol and heating for 10 min at 110 °C, detection by UV at 366 nm. Sensitivity: 0.05 mg/spot.

J.Chinese Herb Med. (Zhongcaoyao) 21, 107-108 (1990). TLC of organophosphorus pesticides on silica with ethyl acetate - hexane 3:2. Detection by EL method. Quantification by densitometry at 272 nm. Detection limits 8 ng.

J. Chromatogr. 704, 540-543 (1995). TLC of dichlorvos and dimethoate on silica gel with n-hexane - acetone - methanol 16:6:1 or with benzene - ethyl acetate - methanol 9:1:1. Selective and sensitive detection by spraying with 2% sodium hydroxide solution followed by 0.5% orcinol solution. Heating at 100°C for 10 min. Detection limit under UV 365 nm of 1 µg and 15 µg per spot for dichlorvos and dimethoate, respectively.