Molecularly imprinted solid-phase extraction method for the high-performance liquid chromatographic analysis of...

A method for molecularly imprinted solid-phase extraction (MISPE) of the fungicide pyrimethanil from wine samples has been investigated. The molecular imprinted polymer was obtained by iniferter-mediated grafting on porous chloromethylated polystyrene beads, using methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. The imprinted beads were evaluated for use as a solid-phase extraction sorbent, in order to develop the extraction protocol in aqueous standards and red wine samples. The optimised extraction protocol resulted in a reliable MISPE method suitable for HPLC analysis (stationary phase: Cromolith Performance C18 column, 100 mm x 4.6 mm; mobile phase: acetonitrile-water (3:2, v/v), flow-rate: 1.00 ml/min; detection 270 nm). It was selective for pyrimethanil and the related pyrimidinic fungicides cyprodinil and mepanipyrim, while the non-pyrimidinic fungicides benalaxyl, chlozolinate, furalaxyl, iprodione, metalaxyl, nuarimol, procymidone and vinclozolin were not extracted. Recoveries performed on a wine matrix spiked with pyrimethanil at three different concentration levels were reproducible and were in good agreement with the recoveries performed on buffer, coming out between 80 and 90% (85+/-7.0% at 0.50 microg/ml, 79+/-1.6% at 2.0 microg/ml and 87+/-5.6% at 20 microg/ml). Preconcentration and quantitative extraction of pyrimethanil from wine samples was shown to be feasible down to 0.1 microg/ml.