A porous composite monolith sorbent of polyaniline, multiwall carbon nanotubes and chitosan cryogel for aromatic compounds extraction

Abstract

A porous composite monolith sorbent of polyaniline, multiwall carbon nanotubes and chitosan cryogel was fabricated and used to extract and enrich aromatic compounds. The fabricated sorbent was characterized and the solid phase extraction condition was optimized. The sorbent was used to extract six aromatic hydrocarbons in tea and coffee under the optimal condition. The method exhibited good linearity in a range from 0.005 to 50 μg L−1 for benzo(a)pyrene and benzo(a)anthracene, 0.025 to 50 μg L−1 for phenanthrene and benzo(b)fluoranthene and 0.05 to 50 μg L−1 for pyrene and dibenzo(a, h)anthracene. The adsorption capacities of the PANI/MWCNTs/Chi sorbent for phenanthrene, pyrene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(a)pyrene and dibenzo(a, h)anthracene were 85, 68, 116, 91, 98 and 61 µg g−1, respectively. The limit of detections and limit of quantifications were between 0.005 and 0.05 and 0.02 and 0.20 μg L−1, respectively. Since the high porosity of the chitosan cryogel prevented the clogging that commonly occurs in conventional particle-packed cartridges, sample loading could be performed at 6.0 mL min−1, which helped reduce sample preparation and analysis time. Good extraction recoveries were achieved between 85.6 and 99.5% with relative standard deviations lower than 7%. Integrating polyaniline and multiwall carbon nanotubes improved the adsorption efficiency of the sorbent and its good stability enabled effective extractions for 12 extraction cycles.