Selective recognition and large enrichment of dimethoate from tea leaves by molecularly imprinted polymers

Molecularly imprinted polymers (MIPs), using dimethoate as the template molecule, were prepared for selective recognition and large enrichment of dimethoate from tea leaves. Six functional monomers were examined, which showed that MIP prepared by methyl methacrylate (MMA) had the largest imprinting factor of 7.9 for dimethoate. Molecular dynamics (MD) simulations were carried out for the six different molecular systems to investigate the recognition mechanism by predicting the interaction energies, the closest approach distances and the active site groups. The dynamic adsorption property of dimethoate on MMA-based-MIP is demonstrated to accord with the Langmuir isotherm. MIP has a marked selectivity for dimethoate compared to other structurally related organophosphorous pesticides. Molecularly imprinted solid phase extraction (MISPE) has a large selective enrichment factor of approximately 100 for dimethoate from tea leaves. It is a useful tool in the trace detection of environmental engineering. (C) 2007 Elsevier B.V. All rights reserved.