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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 °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 μmol 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.

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