Molecularly imprinted polymer based monolith pipette tip for solid-phase extraction of 2,4-dichlorophenoxyacetic acid in aqueous sample

This paper presents a simple approach for fabrication of pipette tip solid-phase extraction (PT-SPE) device, which possesses monolith structure with low back pressure and has high selectivity to 2,4-dichlorophenoxyacetic acid (2,4-D). Pipette tips were packed with molecularly imprinted polymers (MIPs) as selective adsorbent and high-density polyethylene (HDPE) as a co-sintering agent, and then heated to form the monolith extraction device. The key factors including the particle size and amount of packing material, the type and volume of elution solvent, which influence PT-SPE device performance were optimized. Packing material of 40 mg/0.20 mL in the ratio of 4/6 (MIPs/HDPE) and treatment temperature of 150°C were selected. By the determination with high-performance liquid chromatography (HPLC-SPD), the extraction device was found to have a good extraction recovery for 2,4-D lake water sample at the low concentration (0.006 mg/L) with enrichment factor about 50. The proposed method provided simple way for the fabrication of PT-SPE monolith device with reduced back pressure and wall effect, which are very important for the improving extraction efficiency. And the device will have promising application for the extraction of variety of analytes in complex samples.