Development and evaluation of selective coating for stir bar sorptive extraction of silver using sol–gel technique in combination with double-imprinting concept

Abstract

The flexibility and simplicity of stir bar sorption extraction (SBSE) have been combined with the selectivity of ion imprinted polymers (IIP) and a selective and fast extraction and preconcentration method for Ag(I) has been developed. The stir bar was coated with silver imprinted polymer using sol–gel technique in combination with double-imprinting concept. The retained silver was eluted with 250 µL thiourea solution (0.5 mol L⁻¹) at a pH of 3.0–4.0 and was determined by flow injection-flame atomic absorption spectrometry. The factors affecting the separation and preconcentration of Ag(I) were optimized. Under the optimized conditions, the method exhibited a linear dynamic range of 0.5–50 µg L⁻¹ with a detection limit of 0.04 µg L⁻¹ and an enhancement factor of 196. A relative standard deviation of 3.2 % (n = 6) was obtained at the level of 20 µg L⁻¹. The proposed method was successfully applied to the determination of silver in hair, nail and different water samples. The accuracy of the proposed procedure was verified by recovery experiments, independent analysis by electrothermal atomic absorption spectrometry (ET–AAS) and application of the method to the determination of silver in a certified reference material.