Binding behaviour of pyrimethanil-imprinted polymers prepared in the presence of polar co-monomers

Here, we report the evaluation of the molecular recognition properties of a small library of pyrimethanil-imprinted pellicular beads prepared in the presence of several co-monomers of decreasing hydrophobicity, namely N-methacrylamidopiperidine, methylmethacrylate, N-methacrylamidopyrrolidine, N-vinylpyrrolidone, 2-hydroxyethylmethacrylate, acrylonitrile, N-methacrylamidomorpholine, and N,N-dimethylacrylamide. The effect of the presence of these co-monomers on the molecular recognition properties of the beads were studied by eluting the pyrimethanil/Sudan Orange G pair, in the presence of acetonitrile/water mobile phases of increasing polarity. The pyrimethanil was used to probe the specific interactions due to the presence of binding sites. The Sudan Orange G (that is greatly different from the template but with comparable hydrophobicity and molecular mass) was instead used to probe the non-specific interactions due to the bulk of the polymer. The experimental results show that the polymers prepared in the presence of polar co-monomers are characterised by a marked increase of the analytes retention if compared with the imprinted polymer prepared without these co-monomers. The increase of retention is more pronounced for pyrimethanil compared to Sudan Orange G with polymers prepared in the presence of the more hydrophilic co-monomers N-vinylpyrrolidone, acrylonitrile and N-methacrylamidomorpholine, while N,N-dimethylacrylamide is the only co-monomer that does not significantly influence the retention of analytes. Increasing the amount of water in the mobile phase progressively diminishes this effect.