A covalent organic framework-based magnetic sorbent for solid phase extraction of polycyclic aromatic hydrocarbons, and its hyphenation to HPLC for quantitation

A novel covalent organic framework based magnetic adsorbent was developed for magnetic solid phase extraction (MSPE) of polycyclic aromatic hydrocarbons (PAHs). Covalent organic framework-LZU1 (= Lan Zhou University-1) was covalently immobilized onto polyethyleneimine-functionalized magnetic nanoparticles (COF-LZU1@PEI@Fe3O4), and the resulting material was characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. The effects of the pH value of sample solution, percentage of acetonitrile, extraction time and sampling volume on MSPE of six PAHs were investigated. The COF-LZU1@PEI@Fe3O4 displays high extraction efficiency for the PAHs such as pyrene, benzo[a]pyrene, fluoranthene, benz[a]anthracene, benzo[a]fluorathene and dibenz[a, h]anthracene. Following desorption with acetonitrile, the PAHs were quantified by HPLC. The MSPE-HPLC method shows low limit of detection (0.2-20 pg mL(-1)), wide linear range and good reproducibility (relative standard deviations < 4.4% for intra-day and inter-day precision). The method was successfully applied to determine PAHs in environmental samples. Good recoveries were obtained, ranging from 90.9 to 107.8% for water samples and 85.1 to 105.0% for soil samples.