Electrochemical Investigation of Ethinylestradiol Using a Novel Lawsone – Based Electrode

A new, simple voltametric method of ethinylestradiol (EE) determination is presented. Ethinylestradiol is an estrogenic compound widely used for women hormonal therapy. EE is characterized by an extremely high physiological activity, and, primarily because of this property, is an object of numerous studies considering its influence on people and environment. In order to obtain high repeatability of measurements and low detection limits, the working electrode made of glassy carbon was modified with the modification layer consisted of 2-hydroxy-1,4-naphthoquinone and mesoporous carbon (LAW-MC/GC). The electrochemical behaviour of EE on the LAW-MC/GC electrode was investigated using cyclic voltammetry. By using the differential pulse voltammetry, the linear response for analyte was obtained in the concentration range from 0.02 mg ml −1 to 1.5 mg ml −1 , with a detection limit of 0.009 mg ml −1 for preconcentration time of 60 s. Repeatability of the method was measured and determined as RSD % for EE concentration of 0.05 mg ml −1 as 3.6%. The proposed method was successfully applied and validated by studying the recovery of ethinylestradiol in commercially available combined oral contraceptive pills, human fluids samples and certified reference materials.