Sensor Modified with Gold Nanoparticles Stabilized in Dialdehyde Starch/DMSO Matrix for Methyldopa Detection

Abstract

AbstractIn this study, gold nanoparticles (AuNP) were synthesized using a novel stabilizer based on dialdehyde starch polymer (DAS) and dimethyl sulfoxide (DMSO) and the nanomaterial was applied to develop a sensor for methyldopa detection. The nanoparticles were characterized by transmission electron microscopy and the proposed sensor was electrochemically characterized by electrochemical impedance spectroscopy, chronocoulometry and square‐wave voltammetry. Under optimized conditions (0.1 mol L−1 McIlvaine buffer solution at pH 3.5 and 50 μL AuNP/DAS‐DMSO), using square‐wave voltammetry, the calibration curve presented a linear range of 0.99 to 19.60 μmol L−1, with a detection limit of 0.50 μmol L−1. The sensor showed good accuracy, with coefficients of variation of 7.8 % (inter‐day; n=6) and 5.9 % (intra‐day; n=3), and recovery values in the range of 95.3 to 105.2 %. The methyldopa content in a pharmaceutical sample was determined and the results show good correlation with the label value and the method recommended by the Pharmacopoeia, representing a fast and accurate alternative for detecting methyldopa in pharmaceutical products.