A simple and cost-effective voltammetric method for the determination of the synthetic hormone 17α-ethinylestradiol in contraceptive pills using a bare glassy carbon electrode

A simple, cost-effective and environmentally friendly voltammetric method was developed for the rapid and reliable determination of the synthetic estrogen 17α-ethinylestradiol (EE2) in contraceptive pills using an unmodified glassy carbon electrode (GCE). The electrochemical behavior of EE2 was investigated using cyclic voltammetry and linear sweep voltammetry in Britton-Robinson (BR) buffer over a wide pH range. A pH-dependent, irreversible and diffusion-controlled oxidation mechanism involving a two-proton and two-electron process was confirmed. Differential pulse voltammetry (DPV) and square-wave voltammetry (SWV) were optimized for EE2 quantification through systematic evaluation of key instrumental parameters such as modulation amplitude, modulation time and frequency. Under optimized DPV conditions, the method achieved high sensitivity (0.08 μA/μM) with a low limit of detection (60 nM), a wide linear concentration range (0.2–80 μM) and good repeatability (with a relative standard deviation of 5.7%). The method was successfully validated and applied to the analysis of three commercial brands of contraceptive pills, yielding recovery values ranging from 95.0% to 101.0% using the optimized DPV technique. Compared with other electroanalytical methods, the proposed protocol, deliberately employing a bare GCE, demonstrates competitive analytical performance without the need for surface modification, highlighting its suitability for simple routine pharmaceutical quality control and its potential in environmental monitoring applications. • A simple voltammetric method for EE2 determination was developed using a bare GCE. • The oxidation mechanism of EE2 was confirmed as irreversible and pH-dependent. • Optimized DPV provided a low LOD (60 nM) and a wide linear range (0.2–80 μM). • The method was validated and successfully applied to real contraceptive samples. • No electrode modification or pretreatment was required, ensuring practical simplicity.