Electrochemical Impedance Spectroscopic Investigation in Detecting 2,4-dinitrophenylhydrazine Using Catalytic Effect of Copper at Glassy Electrode

This paper reports on the use of electrochemical impedance spectroscopy (EIS) allied to copper (II) for the determination of 2,4-dinitrophenylhydrazine (DNPH) at glassy carbon electrode (GCE). The experiment measurements were carried out in methanol at a potential of 0.3 V versus Ag/AgCl. The Nyquist plots were modeled with a Randle equivalent circuit, by identifying the charge transfer resistance as the relevant concentration dependent parameter. These measurements show that the impedance spectra of DNPH increased by the formation of non-electroactive compound produced from specific interaction between DNPH and Cu (II), which will block the electron-transfer process of the redox probe. Therefore, the proposed methodology offers a detection limit of 4.0×10−8 mol L−1. The proposed methodology was satisfactorily applied to determine DNPH in industrial water samples.