Solid phase microextraction of polycyclic aromatic hydrocarbons from water samples by a fiber coated with covalent...

A covalent organic framework modified graphitic carbon nitride (g-C₃N₄@TpBD) was synthesized by modifying the graphitic carbon nitride (g-C₃N₄) with a covalent organic framework (COF-TpBD). The synthesis conditions including the mass ratio between g-C₃N₄ and benzidine (BD), solvent type, reaction temperature and reaction time were optimized. Under the optimal synthetic conditions, a novel spiny dendritic g-C₃N₄@TpBD adsorbent was obtained. The g-C₃N₄@TpBD was then coated on stainless-steel wire by sol-gel technique and the coated fiber was used for the solid phase microextraction of polycyclic aromatic hydrocarbons prior to gas chromatography-mass spectrometric detection. The established method was successfully applied to determine eight PAHs in six environmental water samples. Under the optimal extraction conditions, a wide linear quantification range for the analytes was obtained from 0.07 to 60.0 ng mL^-1 with the coefficients of determination varying from 0.9979 to 0.9998, and the limits of detection (S/N = 3) ranged from 0.02 to 0.05 ng mL^-1. The relative recoveries of the analytes for the six environmental water samples at the spiked concentrations of 0.2, 0.5, 3.0 and 30.0 ng mL^-1 were between 83.6% and 118% with the relative standard deviations ranging from 2.4% to 11.3%.