Selective and efficient solid-phase microextraction of polycyclic aromatic hydrocarbons in water by robust two-dimensional zinc oxide nanosheets grown on a superelastic nickel-titanium alloy fiber prior to determination by HPLC-UV.

Oriented zinc oxide nanosheets (ZnONSs) were directly grown on pretreated nickel-titanium alloy (NiTi) fiber substrates without a traditional seeding layer of ZnO by electrochemical deposition for the first time. The fiber coatings were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. Direct growth of ZnONSs on the NiTi fiber substrate was dependent on the type of zinc salt. The adsorption performance of the ZnONSs coatings was evaluated using representative aromatic compounds as model analytes together with high performance liquid chromatography with ultraviolet detection. The as-prepared fiber shows higher extraction capability for the selected polycyclic aromatic hydrocarbons (PAHs) than for ultraviolet filters in water samples, and better extraction selectivity for PAHs. For this purpose, the important experimental parameters were optimized for the extraction of PAHs. Under the optimized conditions, the calibration curves are linear in the range of 0.03-200 μg L-1 with correlation coefficients greater than 0.999. Limits of detection ranged from 0.011 μg L-1 to 0.082 μg L-1. Intra-day and inter-day relative standard deviations (RSDs) of the developed method with a single fiber ranged from 2.69% to 4.18% and from 4.44% to 5.40%, respectively. RSDs for the fiber-to-fiber reproducibility varied between 5.57% and 7.66%. The developed method was successfully applied for selective preconcentration and determination of trace PAHs in five real water samples. Relative recoveries varied from 84.5% to 104% with RSDs between 1.65% and 8.30%. Furthermore, the as-prepared fiber is highly stable.