Polímeros de impresión molecular para la determinación de pesticidas

Resumen

Different analytical methodologies based on molecularly imprinting technology have been developed in order to quantify the amount of triazines and benzimidazole compounds present in complex samples. In this sense, two propazine imprinted polymers (M IPs) have been synthesized by precipitation polymerization by either the non-covalent or the semi-covalent imprinting approaches. These imprinted polymers were synthesized using propazine as template molecule, methacrylic acid as functional monomer, ethyleneglycol dimethacrylate as cross-linker, azo-bis-isobutyronitrile as azo-initiator and toluene as porogen. In the case of the semi-covalent imprinted polymer, however, an initial synthetic step had to be carried out prior to polymerization in o rder to prepare propazine methacrylate. It has been demonstrated that both MIPs are able of selectively rebinding both propazine and other triazinic herbicides such as atrazine, simazine, deethylatrazine, and deisopropylatrazine. Propazine-MIPs have been successfully applied to the determination of triazine herbicides (atrazine, simazine, propazine, deethylatrazine, deisopropylatrazine) in soil and vegetable (pea, corn and potato) samples. In order to completely remove non-specific bound interf erents, however, an initial clean-up step of the most complex sample extracts (corn and potatoes) had to be performed prior to MISPE on the non-covalent imprinted polymer. A direct sample clean-up treatment of all the samples could be carried out by the semi-covalent imprinted polymer. Any of the developed methodologies were able of quantitatively recover triazines from spiked samples at concentration levels below the legislated maximum residue limits (MRLs). Two thiabendazole imprinted polymer s have been synthesized by the precipitation polymerization protocol using methacrylic acid as functional monomer and either ethyleneglycol dimethacrylate (EDMA) or divinylbenzene (DVB) as cross-linkers. It has been demonstrated that both polymers ar e able of selectively rebinding thiabendazole and other benzimidazole compounds commonly used as fungicides or anthelmintics in water samples. As the DVB-based imprinted polymer presented a much higher breakthrough volume compared to that of EDMA-MIP , this polymer was selected as selective sorbent for the multiresidual determination of benzimidazole compounds in water samples. Two enrichment procedures of the water samples have been developed, the first one consisting on an off-line MISPE of th