Aplicação eletroanalítica de um eletrodo de pasta de carbono modificado com nanopartículas de magnetita e líquido iônico para a determinação de estrona em alimentos

A carbon paste electrode (CPE) modified with magnetite nanoparticles (Fe3O4NPs) and the ionic liquid(IL)1-butyl-3-methylimidazolium hexafluorophosphate (BMI.PF6) is proposed as a novel detector for determination ofestrone in foods. Estroneis anatural estrogenwhich can be found as residue in meats, since it is one of the metabolites of estradiol, a hormone illegally applied in animal husbandry and, consequently,presentin human foods [1,2]. Therefore, it is necessary to develop new and efficient electrochemical devicesallowing an adequate control of estrone.The CPE/Fe3O4 NPs-BMI.PF6was prepared from conditions optimized using thefactorial design 32 .For this purpose, 133.0mg of graphite powder, 7.0mg of Fe3O4NPs, 45.0mg of mineral oil and 15.0mg ofILBMI.PF6 were used to prepare the modified electrode. The electrochemical behavior of estroneat the proposed modified electrode in 0.2 mol L-1B-R buffer solution (pH 12.0) was studied by cyclic voltammetry. A single oxidation peak at +0.365V was observed, characterizing an irreversible process.The anodic current increased by a factor of five times compared with the unmodified CPE, justifying its use as detector for estrone. The calibration curve for the estrogenwas obtained by square wave voltammetry(SWV). The variables frequency, pulse height and scan increment were evaluated by Box-Behnken design. Under optimized conditions (f = 30 Hz; a = 90 mV and ΔEs = 2.8 mV), the calibration curveexhibited twolinear ranges: the first between 4.0 and 9.0 μmol L-1and the second between 9.0 and 100.0 μmol L-1. The analytical studies were carried out using the second linear range(Δi/μA = 0.046 + 1.097[Estrone]/μmol L−1, R = 0.998), since it is larger. The limits of detection and quantification were 3.08 and 9.34 μmol L-1,respectively. The proposed modified electrode was successfully applied to the determination of estrone in complex matricesas pork meat samples. The results were comparable to those obtained using the UV-vis technique. The statistic treatments demonstrated the precision and accuracy of data delivered by thenovel modified electrode.