Desenvolvimento de um método analítico para determinação de Se em peixes por FIA-HG-AAS após pré-concentração utilizando microextração dispersiva em fase sólida com nanopartículas de GO/γ-Fe2O3

Abstract

An analytical method for preconcentration of Se in fish samples using magnetic nanoparticles of graphene oxide (GO)/γ-Fe2O3 with detection by atomic absorption spectrometry and hydride generation by flow injection (FIA-HG-AAS) was developed. The morphology and surface properties of the adsorbent were characterized by infrared vibration spectroscopy with Fourier Transform (FT-IR), scanning electron microscopy (SEM) and diffraction (XRD). Parameters involved in microwave-assisted digestion were optimized, such as HNO3 concentration and sample mass used. The domain of the factors pH, MNPs mass and adsorption time were optimized through a central composite, as well as the flow of carrier gas, the concentration of HCl and NaBH4 for the hydride generation system. The optimized conditions were pH 2, 60 mg of MNPs e 30 min for the adsorption process taking into account matrix effects and 4.5 (v/v) % de HCl, 0.19 (m/v) % de NaBH4 e 273.5 mL min-1 flow of carrier gas for hydride generation. Under optimized conditions, the enrichment factor (EF), the limits of detection (LD) and quantification (LQ) were 70; 0.03 μg g-1; 0.09 μg g-1, respectively. The intermediate precision of the method, defined by the relative standard deviation (RSD) (n=10) was 7.54% for Se. The accuracy of the method was assessed through addition and recovery tests, as well as the analysis of a certified reference material (CRM). The recovery values ranged from 103.8 to 117.3% and the Se concentration determined in the CRM was in accordance with the certified value through a 95% confidence level t-test.