▎ 摘　　要

In present work a simple methodology for electroanalytical sensing of diethylstilbestrol (DES) using graphene quantum dots (GQD) surface modified screen-printed electrodes (SPE) is reported. GQD was synthesized by simple bottom-up method based on citric acid pyrolysis at 200 degrees C and electrodeposited directly at electrode surface under cyclic voltammetric conditions. The obtained GQD presented an average diameter of 7 nm and was characterized by techniques such as transmission and scanning electron microscopy, and electrochemical impedance spectroscopy. The proposed sensor exhibits a linear response from 0.05 to 7.5 mu mol L-1, with limit of detection and quantification of 8.8 nmol L-1 and 29.0 nmol L-1, respectively. The repeatability study presented RSD=3.6 % for 6 consecutive measurements using the same electrode surface and the reproducibility study showed RSD=6.6 % for measurements with 6 different electrode surfaces. The proposed sensor was successfully applied for DES determination in synthetic urine and tap water spiked samples and good recoveries were obtained without any sample pre-treatment, showing its promising analytical performance.