RESUMO
Hydrothermal oxidation was used to prepare a nickel-titanium alloy ( NiTi ) solid-phase microextraction fiber. The experimental results demonstrated that a nanoporous NiTi oxide composite coating was in situ grown on the surface of NiTi substrate by direct oxidation in aqueous H2 O2 solution at 80℃. The resulting composite oxide coating included more nickel and less titanium. The prepared NiTi fiber with Ni-rich oxide coating was used to extract typical aromatic compounds coupled with HPLC-UV and exhibited good extraction selectivity for polycyclic aromatic hydrocarbons ( PAHs). The key factors affecting extraction efficiency of PAHs were examined. Under the optimized conditions, the calibration curves were linear in the range from 0. 05 to 500 ng / mL with correlation coefficients ≥0. 999, and the limits of detection were 0. 026-0. 056 ng / mL. Furthermore, the relative standard deviations ( RSDs) for intra-day and inter-day repeatability of the single fiber varied from 4. 8% to 6. 2% and from 5. 4% to 6. 5% for five replicates of PAHs at the spiking level of 50 ng / mL, respectively. The RSDs for the fiber-to-fiber reproducibility of five fibers prepared in different batches ranged from 6. 4% to 8. 4% . This method was suitable for selective enrichment and detection of target PAHs in environmental water samples with relative recoveries of 87. 4% -108. 2% and RSDs <8. 1% . Moreover, this novel NiTi fiber was mechanically strong and chemically stable, and its preparation was precisely controllable.