Preparation of a mixed-mode of hydrophobic/cation-exchange polymer monolith and its application to analysis of six antidepressants in human plasma

摘要

A hydrophobic/cation-exchange polymer monolith was prepared via one-step thermally initiated polymerization of 2-acrylamido-2-methyl-1-propyl-sulfonic acid (AMPS), divinylbenzene (DVB) and ethylene glycol dimethacrylate (EDMA) in a capillary. The use of DVB and EDMA as binary crosslinking monomers help to increase the specific surface area and enhance hydrophobicity of the target monolith. The as-obtained monolith was characterized by diffuse reflectance infrared spectroscopy, scanning electron microscopy, nitrogen adsorption-desorption and mercury intrusion porosimetry. The results show that the monolith has favorable permeability and well mechanical strength. Furthermore, its specific surface area is up to 353 m~2 g~(-1). The as-prepared monolith was used as a sorbent for polymer monolith microextraction (PMME), which was coupled to high performance liquid chromatographic-electrospray ionization-mass spectrometric (HPLC-ESI-MS) analysis in offline mode for the determination of antidepressants in biological samples. The results show that the monolith with hydrophobic and strong cation-exchange functional groups exhibits high extraction efficiency towards the antidepressants. The limits of detections (S/N = 3) for the antidepressants in plasma samples were in the range of 0.06-0.39 ng mL~(-1) and the recoveries were from 73.2% to 110.8% (depending on the analytes), with relative standard deviations (RSDs) less than 9.8%.