Carbon paste electrode modified with ferrimagnetic nanoparticles for voltammetric detection of the hormone estriol

A very simple, novel and environmentally-friendly electrochemical detector for estriol, based on a carbon paste electrode modified with ferrimagnetic nanoparticles, is proposed herein. The ferrimagnetic nanoparticles increase the surface area of the electrode and act as a catalyst for the electrochemical reaction of estriol. Estriol is an estrogen naturally produced by women during pregnancy. Its imbalance may engender disruption of the endocrine system, thereby impairing human growth and reproduction. Estriol is also considered to be an emergent pollutant. The proposed modified carbon paste electrode was used for the determination of estriol by anodic square-wave voltammetry. In 0.1 mol L− 1 B-R buffer (pH 6.0), estriol presented a well-defined single oxidation peak at + 0.68 V, indicating that under these conditions the electrochemical process is irreversible. The overall reaction rate is controlled by an adsorption step. Two protons and two electrons are involved in the estriol oxidation. The calibration curve for estriol showed good linearity in the concentration range of 0.86 to 32.0 ppm (R2 = 0.997). The detection and quantification limits achieved were 0.79 and 2.41 ppm, respectively. The proposed modified electrode was successfully applied to the analysis of pharmaceutical and simulated urine samples; the results being comparable to those obtained using the UV-vis technique.