Modified ionic liquid-coated nanometer TiO2 as a new solid phase extraction sorbent for preconcentration of trace nickel

•1-Hexadecyl-3-methylimidazolium bromide was coated on TiO2 nanoparticles at pH 10.•TAN was immobilized on IL-coated nanometer TiO2 and used as an efficient sorbent.•TAN–IL-nanometer TiO2 has an extremely high adsorption capacity for Ni(II) ions.•The sorbent was applied to the preconcentration of Ni from food and water samples.

In this work, a high-capacity solid-phase extraction sorbent was developed for preconcentration of trace amounts of nickel ions prior to their determination by flame atomic absorption spectrometry (FAAS). The sorbent was prepared by immobilization of 1-(2-thiazolylazo)-2-naphthol (TAN) on nanometer-sized TiO2 coated with the ionic liquid, 1-hexadecyl-3-methylimidazolium bromide (C16mimBr). The chemical conditions for preparation of sorbent including pH and amounts of TAN and C16mimBr were optimized. Experimental conditions for preconcentration of Ni, elution conditions and the effect of interfering ions on the recovery of the analyte were also investigated. Under the optimum conditions, the calibration graph was linear in the range of 2.0–400 μg L−1 with a detection limit of 0.8 μg L−1. The adsorption capacity of the sorbent for Ni(II) was found to be 630 mg g−1. The preconcentration method coupled with FAAS was successfully applied to the determination of Ni(II) in various water and food samples.

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