Optimized preconcentration method using magnetic dispersive solid-phase microextraction with GO–γFe2O3 nanoparticles for the determination of Se in fish samples by FIA-HG-AAS

Abstract

This work describes the development of an analytical method for the preconcentration of Se in digested fish samples using magnetic nanoparticles of graphene oxide GO–γFe₂O₃ with detection by hydride generation atomic absorption spectrometry and flow injection analysis (FIA-HG-AAS). The magnetic nanoparticles (MNPs) were synthesized and their structural properties were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The domain of the factors pH, MNP mass, and adsorption time was optimized using a central composite design, as well as the carrier gas flow, the concentrations of hydrochloric acid (HCl) and sodium borohydride (NaBH₄) for the hydride generation system. The optimized experimental conditions were obtained to be pH 2, 60 mg of MNPs, and 30 min for the adsorption process, and 4.5% (v/v) HCl, 0.19% (m/v) NaBH₄, and 273.5 mL min⁻¹ carrier gas flow for hydride generation. Under the optimized conditions, the enrichment factor (EF), the limits of detection (LOD), and quantification (LOQ) were 70, 30 ng g⁻¹, and 90 ng g⁻¹, respectively. The short-term precision of the method, defined by the relative standard deviation (RSD) (n = 10), was 7.54%. The accuracy of the method was assessed through recovery tests, as well as the analysis of certified reference materials (CRMs). The recovery values ranged from 103.8 to 117.3%, while the Se concentration determined in the CRMs were in agreement with the certified values obtained through a t-test at a 95% confidence level.