Electrochemical Determination of 17‐<i>α</i>‐Ethinylestradiol on a Graphene Quantum Dots and Carbon‐Black‐Modified Glassy Carbon Electrode

A simple and inexpensive electrochemical sensor based on a glassy carbon electrode (GCE) modified with graphene quantum dots and carbon black nanoparticles (dihydrogen phosphate polyelectrolyte) is applied to determination of the emerging contaminant the estrogen 17‐ α ‐ethinylestradiol (EE2). The combination of this nanocomposite with the GCE has not yet been explored as an electrochemical sensor. Combined, these materials create a synergy that enhances the overall performance of the oxidative detection system, resulting in a more efficient and accurate detection. The analytical curve presents a linear dynamic range from 0.998 to 10.0 µmol L −1 , with a detection limit of 0.998 µmol L −1 . Addition and recovery studies are carried out on a lake water sample, showing a recovery of 92.3%. The accuracy of the developed method is also evaluated by determining EE2 in pharmaceutical formulation samples. The obtained results are in statistical agreement with those obtained using high‐performance liquid chromatography–diode array detector at a confidence level of 95%. Therefore, the electrochemical sensor developed presents a fast construction procedure and the electroanalytical method for EE2 determination proves to be precise and accurate, with low consumption of reagents and a low relative cost.