REVIEWS IN ANALYTICAL CHEMISTRY, cilt.28, sa.2, ss.137-149, 2009 (SCI-Expanded)
The overlapping voltammetric signals of levodopa and benserazide in their binary mixture were processed by continuous wavelet transform and the transformed signals were used for the simultaneous determinations of these compounds in commercial pharmaceutical formulation. The Osteryoung Square Wave Voltammograms of levodopa and benserazide in Britton Robinson (BR, pH = 3) buffer were plotted in the potential range of -196 and 1200 mV using glassy carbon electrode versus Ag/AgCl reference electrode. To find an optimal signal processing method, various continuous wavelet family with different the scale parameter (a) was tested and Haar continuous wavelet transform method (a = 4) was found to be the optimal wavelet transform for the signal processing and determination. Calibration functions in the linear dynamic range of 4.0-18.0 mu g mL(-1) for levodopa and 2.0-10.0 mu g mL(-1) for benserazide were obtained by measuring the transformed voltammetric amplitude at 460 mV and 320 mV for levodopa and benserazide, respectively. The proposed analytical signal processing method was validated by analyzing the independent set of the synthetic binary mixtures containing levodopa and benserazide. The mean recoveries and relative standard deviations were found to be 98.9 % and 2.31 % for levodopa 101.6 % and 1.76 % for benserazide. This proposed method was applied to the real samples consisting of levodopa and benserazide in the commercial pharmaceutical as capsules. The experimental results obtained from the Haar continuous wavelet transform method were compared with those obtained by the literature method. A good agreement was observed for the obtained results.