ИСТИНА

In recent years, molecularly imprinted polymers (MIPs) have been used increasingly extensively for the selective separation of organic compounds by solid-phase extraction. MIPs are largely synthesized by the noncovalent imprinting method. The synthesis scheme includes several stages, such as the formation of an intermolecular prepolymerization complex between functional monomer (FM) and template (T) molecules, the polymerization of this complex in the presence of large amounts of a cross-linking agent providing the production of a polymer with a rigid structure, polymer grinding and sieving to obtain particles with the desired size, and multiple washing by organic solvents to remove the template from the polymer. In this work, by the noncovalent imprinting technique, we synthesized new MIPs with molecular imprints of 2,4-dichlorophenoxyacetic acid (2,4-D), 3,6-dichloro-2-methoxybenzoic acid (3,6-DMB, dicamba) and (RS)-1-p-chlorophenyl-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)pentan-3-ol (RS). The synthesis was performed by the technique of bulk radical polymerization. Acrylamide was used as a functional monomer, and ethylene glycol dimethacrylate as a cross-linking agent. Polymerization was initiated by 2,2'-azobisisobutyronitrile. The goal of this work was to study the factors varied at the stage of MIP synthesis (the FM : T ratio in the prepolymerization mixture, the nature of template and solvent molecules) and influencing the specific surface area of polymers and their sorption properties. The sorption isotherms were plotted and the values of imprinting factors (IF) were calculated for the chlorine-containing pesticides in order to compare their binding properties. It was found that specific surface area and sorption characteristics of the polymers with molecular imprints of chlorine-containing pesticides depended on the nature of template molecules, functional monomer : template ratio in the polymerization mixture, and nature and content of solvents varied at the synthesis stage. The difference in the sorption behavior of molecularly imprinted and reference polymers was observed over a wide range of chlorine-containing pesticide concentrations. The selectivity of the adsorbent with 2,4-D imprints was estimated for the example of structurally related compounds (3,4-dichlorophenoxyacetic acid, 2,4-dichlorophenol, 2-, 3- and 4-chlorophenols). The synthesized polymers were used for solid-phase extraction of 2,4-D, dicamba and 2,4-dichlorophenol.