Abstract:

A novel silica-based solid-phase microextraction (SPME) fiber was successfully fabricated by the immobilization of silica nanoflakes (SiO₂NFs) onto the hydrothermally treated nickel-titanium alloy (NiTi) wire using sol-gel method, followed by self-assembled surface modification of phenyltrichlorosilane. The extraction performance of the fabricated fiber was evaluated using typical aromatic compounds in direct-immersion mode of SPME. The fiber exhibited the high extraction capability and good extraction selectivity for polycyclic aromatic hydrocarbons (PAHs) in water samples. The influences of stirring rate, extraction temperature, extraction time and ionic strength on the extraction efficiencies were optimized coupled to HPLC with UV detection. Under the optimized conditions, the five PAHs presented good linearity in the certain mass concentration ranges with correlation coefficients (r) greater than 0.999, and LODs ranged from 0.013 to 0.108 μg/L. The intra-day and inter-day RSDs were from 4.1% to 5.9% and 4.8% to 6.8% for the PAHs at the spiked level of 50 μg/L with the single fiber, respectively. The recoveries of the five PAHs in real water samples spiked at 10 μg/L and 30 μg/L ranged from 90.8% to 105.7% and 93.6% to 103.1%, respectively. Moreover, the phenyl-modified SiO₂NFs coated NiTi fiber has high stability and good preparation reproducibility. The developed method is suitable for the concentration and determination of the target PAHs in environmental water samples.

Key words: nickel-titanium alloy (NiTi) wire, polycyclic aromatic hydrocarbons (PAHs), silica nanoflakes (SiO₂NFs), solid-phase microextraction (SPME)