Eletrodo modificado com nanopartículas ferrimagnéticas e quitosana para detecção de etil paration em amostras de alimentos

Nanomaterials show a high surface area and mayexhibit excellent electrocatalytic activity. Thus, when appliedin electrode modification, allow obtaining of electrochemical devices capable of measurements with a high sensitivity, precision and accuracy [1,2]. Iron oxide nanoparticles (nano-Fe3O4), due totheir peculiar properties,as low toxicity and superparamagnetism has become one of the most used materials in the development of new electrochemical devices. The objective of this work was to modify, characterize and apply electrodes modified with nano-Fe3O4 for the determination of the ethyl parathion (EP). The EP is a nitro compound used as a pesticide to eliminate insects and prevent pests in food culture. It is considered an endocrine disruptor, because even in small concentrations, it can cause numerous changes in the human organism[3]. The nano-Fe3O4with an average diameter of 50 nmwere purchased from Sigma-Aldrich and dispersed in a chitosan solution(0.25%w/v).The detector was prepared by dripping 5.0μL of the nano-Fe3O4 dispersion onto the glassy carbon substrate, followed by vacuum drying.Preliminary studies using cyclic voltammetry showed that EP exhibits an oxidation peak at +0.05V and two reduction signals at 0.0and −0.59V.For analytical determination the signal in −0.57 V was used and othersexperimental parameters were optimized (concentration of the nano-Fe3O4, pH,supporting electroly teand electroanalytical technique). The increase in cathodic current of reduction signal, compared to bare electrode, justifies the use of nano-Fe3O4/GCE. For calibration curve, was used square wave voltammetry employing the following conditions: f=40 Hz; a=40 mV and ΔEs=4 mV.The square-wave voltammograms showed a well-definedreduction peak at −0.59 V.The calibration curve for EP presenteda good linearity in the concentration range of 0.34 to 3.1 μmol L−1 (R=0.997). The limits of detection and quantification obtained were 0.13μmol L−1and 0.39 μmol L−1, respectively.Finally, the proposed detector was applied for quantification of EP in samples of tomato, lettuce, carrot, orange and rice.The data obtained using the proposed detector were compared to those obtained by UV-vis spectroscopy and the results were satisfactory and concordant.