Preconcentration of 2,4-dichlorophenoxyacetic acid on molecularly imprinted polymers and its subsequent determination by high performance liquid chromatography

The potency of molecularly imprinted polymers ( MIP ) for 2,4-dichlorophenoxyacetic acid ( 2,4-D ) in the dynamic sorption preconcentration (solid phase extraction) of 2,4-D and three other structurally related species (2,4-dichlorophenol, 2-chlorophenol, and dikamba) from aqueous solutions is assessed. The optimal conditions for preconcentration are found: 0.01 M HCl, 25–100 mL of solution, flow rate of solution 0.7 mL/min, column (15 × 2.7 mL), and sorbent weight 0.04 g. The analytes are desorbed with 1 mL of methanol and detected in the eluate by reversed-phase HPLC with spectrophotometric detection at 225 nm. The detection limit for 2,4-D makes 0.4 μg/mL without preconcentration and 0.01 μg/mL with preconcentration from a volume of 100 mL. The procedure is applied to the analysis of model mixtures based on fresh river water.