Effect of template size on the selectivity of molecularly imprinted polymers for phenylurea herbicides

Four different methacrylic acid-based, molecularly imprinted, polymers, using fenuron or isoproturon as template and acetonitrile or toluene as porogen, were prepared in order to evaluate the template size effect on the selectivity and the porogen effect on the affinity of recognition in molecular imprinting solid-phase extraction. The results of different tests applied to both polymers have shown that fenuron-polymers were highly selective whereas isoproturon-polymers were able to recognise several structurally related compounds (metoxuron, fenuron, metobromuron, chlortoluron, linuron and chlorbromuron). On the other hand, the polymers prepared using toluene as porogen showed a higher affinity for the tested compounds than those prepared in acetonitrile. Accordingly, the isoproturon-imprinted polymer prepared in toluene has been evaluated as a new sorbent in solid-phase extraction procedures for the trace-enrichment and clean-up of phenyureas in ground water and soil samples.