Evaluation of polydopamine supported nano-polytetrafluoroethylene as a novel material for solid phase extraction

Abstract

A novel material for solid phase extraction (SPE) was prepared by the deposition of polydopamine onto nano-polytetrafluoroethylene (PTFE) using a simple self-assembly approach. The coated nano-PTFE was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The adsorption mechanism of the prepared material, as a SPE adsorbent, was investigated through static and dynamic adsorption experiments. Four alkaloids and two amino acids were used as model analytes. Several operation parameters including adsorption time and solution pH were optimized in the static adsorption mode. The coated nano-PTFE displayed a strong adsorption capability for four alkaloids, and isocorydione could be selectively adsorbed under the optimized pH. Hydrophobic and hydrogen-bonding interactions are the two main driving forces for the adsorption of the analytes. When the two coexist, the hydrogen-bonding interactions are more important than the hydrophobic effects. The prepared material exhibited almost opposite adsorption behavior compared with C18 silica without end-capping treatment. Therefore, polydopamine coated nano-PTFE can be used as packing material for a reverse phase HPLC column, instead of C18 with a tedious treatment of end-capping.