Binding properties of 2,4,5-trichlorophenoxyacetic acid-imprinted polymers prepared with different molar ratios between template and functional monomer.

Several molecularly-imprinted polymers binding the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) were prepared with a molar ratio between the functional monomer and the template molecule in the pre-polymerisation mixture set between 1+2 and 20+1. The functional monomer used was 4-vinylpyridine (4-VP), the cross-linker was ethylene dimethacrylate, and the porogenic solvent was a mixture of methanol-water 3+1 (v/v). The polymers obtained were grinded, sieved and packed in 100 mm x3.9 mm HPLC columns. The effects of the mobile phase composition were evaluated by eluting the columns with acetonitrile-water mixtures. The results obtained indicate that column capacity, selectivity factor and the imprinting effect are controlled by ion-pair and hydrophobic interactions between the analyte and the stationary phase. In the full range of ratios considered, column capacity, selectivity factor and imprinting effect are inversely proportional to the molar ratio between the template molecule and the functional monomer.