Simultaneous Determination of Benserazide and Levodopa in Pharmaceutical Tablet, Human Serum and Urine Sample by Differential Pulse Voltammetry Using Modified Glassy Carbon Electrode

A simple and highly sensitive method was investigated for the simultaneous determination of benserazide (BZ) and levodopa (LD) using Poly(4-(2-pyridylazo)-resorcinol) (PAR) modified glassy carbon electrodes. Both benserazide and levodopa were accumulated at the surface of the modified glassy carbon electrode (under open circuit condition for 30 s). In differential pulse voltammetry technique both BZ and LD were given sensitive oxidation peaks at 180 mV and 270 mV, respectively. Under the optimized experimental conditions (such as supporting electrolyte pH, accumulation time and scanning rate) BZ and LD were shown linear response over the range of 0.01-0.20 mM (r(2) = 0.991) and 0.025-0.4 mM (r(2) = 0.993), respectively. The lower detection limits were found to be 0.002 mM for BZ and 0.006 mM for LD. The commonly encountered excipients used in the pharmaceutical formulation showed no interference with the selective determination of BZ and LD. The investigated method showed good stability, reproducibility (1.3% (BZ) and 2.3% (LD)), repeatability (1.9%) and high recovery in pharmaceutical preparation (1.7% (BZ) and 2.7% (LD)), human serum (1.7% (BZ) and 1.9% (LD)) and urine samples (1.7% (BZ) and 1.8% (LD)).