Gold nanoparticle modified NiTi composite nanosheet coating for efficient and selective solid phase microextraction of polycyclic aromatic hydrocarbons

A novel, uniform nanosheet coating was hydrothermally grown in situ on pretreated NiTi alloy wire in an aqueous NaOH solution. The nanosheets were covalently linked to the NiTi substrate and crosslinked. They were radially oriented around the NiTi wire and composed of more titanium oxide than nickel oxide (TiO2/NiO). The TiO2/NiO composite nanosheet (TiO2/NiOCNSs) coating exhibited a porous structure, providing a desirable nanostructured support for subsequent uniform electrodeposition of AuNPs, which greatly improved the available surface area. The extraction performance of the AuNPs modified TiO2/NiOCNSs coated NiTi fiber was evaluated using aromatic compounds as model analytes and was coupled to HPLC with UV detection. The results obtained indicated that the novel fiber exhibited excellent extraction efficiency and good selectivity for polycyclic aromatic hydrocarbons (PAHs). The main experimental factors for PAHs extraction were optimized. Under the optimized conditions, good linearity was obtained in the range of 0.05-350 mu g L-1 with correlation coefficients greater than 0.998. The limits of detection for the developed method ranged from 0.012 mu g L-1 to 0.053 mu g L-1. The single fiber repeatability and fiber-to-fiber reproducibility were less than 6.05% and 7.19%, respectively. The developed method was successfully applied to the selective concentration and sensitive determination of trace PAHs in different environmental water samples. Relative recoveries varied from 86.3% to 104% at spiking levels of 7 mu g L-1 and 30 mu g L-1 with relative standard deviations in the range of 4.4-7.5%. Furthermore, the novel fiber could be fabricated in a highly reproducible manner, and had a high stability and long life span.