REVERSED-PHASE THIN-LAYER CHROMATOGRAPHY OF VARIOUS PESTICIDES IN THEPRESENCE OF WATER-SOLUBLE BETA-CYCLODEXTRIN POLYMER

The modification of the hydrophobicity of 28 commercial pesticides wit h a water-soluble beta-cyclodextrin polymer (SCDP) in the presence of aqueous Nacl has been studied by reversed-phase thin-layer chromatogra phy. The pesticides formed inclusion complexes with SCDP and these com plexes are less lipophilic than the parent pesticides. The sodium chlo ride exerted a typical salting-out effect, the retention of each pesti cide increased with increasing concentration of the salt in the eluent . This effect can be tentatively explained by the suppression of the d issociation of the polar groups in the solute molecules resulting in i ncreased apparent lipophilicity. The correlation between lipophilicity and salting-out effect was found to be significant, that is the salti ng-out effect increases with increasing polarity (lower lipophilicity) of the pesticides, whereas the lipophilicity has negligible influence on the inclusion-forming capacity of non-homologous series of pestici des.