Efficient Detection of Droxidopa in the Presence of Carbidopa Using a Modified Screen-Printed Graphite Electrode

The determination of pharmaceutical compounds in various samples is considered an effective way to evaluate their effectiveness. Nanomaterials-based electrochemical sensors have proven to offer the desired affordability, portability and high-performance for this purpose. In this work, an electrochemical sensor is described to detect droxidopa in the presence of carbidopa using a screen-printed graphite electrode (SPGE) modified with graphitic carbon nitride (g-C3N4). Admirable electrocatalytic behavior was found for g-C3N4/SPGE towards the droxidopa oxidation, with minimized oxidation overpotential and boosted voltammetric response peak current. Under the optimal circumstances, the peak currents of droxidopa oxidation were proportional to its concentrations (0.15-325.0 mu M), with the limit of detection of 0.04 mu M. Also, this sensor was applied to detect droxidopa in the presence of carbidopa. The g-C3N4/SPGE successfully resolved the oxidation signals of droxidopa and carbidopa, and the peak separation was calculated to be 310 mV. The g-C3N4/SPGE presented good stability, and repeatability. Finally, the developed g-C3N4/SPGE sensor displayed a satisfactory recovery of the spiked droxidopa and carbidopa in real-sample matrices (tap water and urine).