Nanomodified Screen-Printed Electrode for direct determination of Aflatoxin B1 in malted barley samples

Abstract

The present work describes a facile synthesis of a nanocomposite based on gold nanoparticles (NPAu) and graphene quantum dots (GQD) and its use as an electrode modifier for a non-biological alternative of Aflatoxin B1 (AFB1) voltammetric determination. TEM and SEM techniques showed a uniform and well-distributed dispersion of gold nanoparticles (19 ± 6 nm of average size) and GQD, which was used as a reducing and stabilizing particle formation. Modified screen-printed electrode (NPAuGQD-SPE) was characterized by electrochemical experiments, as linear voltammetry and electrochemical impedance spectroscopy. A significative electrocatalytic effect was observed towards AFB1 oxidation using the proposed device, shifting the peak potential to less positive values and improving the voltammetric response. EIS experiments showed lower RCT values for the modified electrodes, calculated as 117 Ω, 14.9 kΩ, and 40.3 kΩ for NPAuGQD-SPE, GQD-SPE, and SPE, respectively. Under optimized conditions, an analytical curve with linear region of 1.0–50.0 nmol L−1 was obtained, reaching detection and quantification limits of 0.47 and 1.5 nmol L−1, respectively. Samples of malted barley were fortified based on the maximum residue limit (MRL) allowed by Brazilian legislation, and recoveries in the range of 76–103% were obtained, indicating that there is no significant matrix effect, considering the low concentration values used and simple sample treatment.