A new strategy for enhanced fabrication of flake-like zinc–aluminum layered double hydroxide on nickel–titanium alloy fiber for highly efficient solid-phase microextraction of ultraviolet filters

Abstract

A new flake-like zinc–aluminum layered double hydroxide (ZnAl-LDH) coating was firmly fabricated on a superelastic nickel–titanium alloy (NiTi) wire. Herein, the NiTi wire was hydrothermally treated for the in-situ growth of nickel and titanium oxide nanoflakes (NiTiONFs) and used as a fiber support for subsequent growth of ZnAl-LDH nanoflakes. The resulting coating was able to selectively extract the studied ultraviolet filters (UVFs) more effectively and quickly in comparison with the commercial polyacrylate and polydimethylsiloxane fibers. This fiber shows long recycling lifetime due to the ZnAl-LDH coating embedded into the active NiTiONFs support with high mechanical stability. For this purpose, main experimental parameters including temperature, stirring rate, extraction and desorption time, and ionic strength were investigated and optimized in detail. Under the optimized conditions, good linearity was obtained for the developed SPME–HPLC–UV method with the NiTi@NiTiONFs@ZnAl-LDH fiber. Limits of detection were between 0.009 μg L−1 and 0.052 μg L−1 for five UVFs. Intra-day and inter-day relative standard deviations (RSDs) for single fiber repeatability were less than 6.4% and 6.6% for five replicate extractions of UVFs at the spiking level of 50 μg L−1. RSDs for fiber-to-fiber reproducibility varied from 6.3% to 6.9%. The developed method was successfully used for the determination of UVFs in snow water, river water and wastewater samples. The relative recoveries of 80.1%–109% were achieved. Thus the developed method could be potentially applied to selective enrichment and determination of UVFs in different environmental water samples.