Simultaneous Electrochemical Sensing of Methyldopa and Hydrochlorothiazide using a Novel ZnO/Al2O3 Nanocomposite Modified Screen Printed Electrode

In this study, ZnO/Al2O3 nanocomposite modified graphite screen printed electrode (ZnO/Al2O3/SPE) was fabricated for the simultaneous determination of methyldopa and hydrochlorothiazide. The modified electrode was also employed to study the electrochemical oxidation of methyldopa and hydrochlorothiazide, using cyclic voltammetry (CV), chronoamperometry and differential pulse voltammetry (DPV) as diagnostic techniques. This modified electrode shows excellent electrocatalytic activity towards the oxidation of methyldopa with a potential shift about 240 mV to a less positive potential. Differential pulse voltammetry exhibits linear dynamic ranges from 1.0×10−6 to 1.0×10−4 M and 1.0×10−7 to 1.0×10−4 M for methyldopa and hydrochlorothiazide respectively. Under optimized experimental conditions, the detection limits of methyldopa and hydrochlorothiazide were calculated as 0.5 μM and 0.08 μM respectively, at this simple construction sensor. Finally, the fabricated sensor was satisfactorily used for the simultaneous determination of methyldopa and hydrochlorothiazide in methyldopa tablets, hydrochlorothiazide tablets and urine samples.