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

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.