Preparation of metal wire supported solid-phase microextraction fiber coated with multi-walled carbon nanotubes

Multi-walled carbon nanotubes-coated solid-phase microextraction fiber was prepared by a novel protocol involving mussel-adhesive-protein-inspired polydopamine film. The polydopamine was used as binding agent to immobilize amine-functionalized multi-walled carbon nanotubes onto the surface of the stainless steel wire via Michael addition or Schiff base reaction. Surface properties of the fiber were characterized by field emission scanning electron microscope and X-ray photoelectron spectroscope. Six phenols in aqueous solution were used as model compounds to investigate the extraction performance of the fiber and satisfactory results were obtained. Limit of detection was 0.10 μg/L for 2-methylphenol (2-MP) and 4-methylphenol (4-MP), and 0.02 μg/L for 2-ethylphenol (2-EP), 4-ethylphenol (4-EP), 2-tert-butylphenol (2-t-BuP), and 4-tert-butylphenol (4-t-BuP), which were much lower than commercial fiber and fibers made in laboratory. RSDs for one unique fiber are in the range of 1.92-7.00%. Fiber-to-fiber (n=3) reproducibility ranges from 4.44 to 8.41%. It also showed very high stability and durability to acid, alkali, organic solvent, and high temperature. Real water sample from Yellow river was applied to test the reliability of the established solid-phase microextraction (SPME)-GC method and recoveries with addition level at 5 and 100 μg/L were in the range from 81.5 to 110.0%.