Simultaneous differential pulse voltammetric determination of L-dopa and carbidopa in pharmaceuticals using a carbon paste electrode modified with lead dioxide immobilized in a polyester resin

Abstract

Um eletrodo de pasta de carbono modificado com dióxido de chumbo imobilizado em uma resina de poliéster foi desenvolvido para a determinação voltamétrica de pulso diferencial simultânea de L-dopa e carbidopa em formulações farmacêuticas. As curvas analíticas foram lineares em uma faixa de concentração de 2,6 × 10 -4 a 1,2 × 10 -3 mol L -1 e de 3,2 × 10 -5 a 1,5 × 10 -4 mol L -1 para L-dopa e carbidopa, respectivamente. Os limites de detecção foram 2,5 × 10 -5 mol L -1 e 3,7 × 10 -6 mol L -1 para L-dopa e carbidopa, respectivamente e as recuperações de L-dopa e carbidopa em duas amostras variaram de 98,1 a 103%. Os desvios padrão relativos foram menores que 2,5% para soluções 1,2 × 10 -4 e 1,2 × 10 -3 mol L -1 dessas catecolaminas e os resultados obtidos para L-dopa e carbidopa em formulações farmacêuticas usando o procedimento voltamétrico proposto estão em boa concordância com os valores rotulados ou com aqueles teores determinados empregando-se um procedimento enzimático a um nível de confiança de 95%.A carbon paste electrode modified with lead dioxide immobilized in a polyester resin has been developed for simultaneous differential pulse voltammetric determination of L-dopa and carbidopa in pharmaceutical formulations. The analytical curves were linear in the concentration ranges from 2.6 × 10 -4 to 1.2 × 10 -3 mol L -1 and from 3.2 × 10 -5 to 1.5 × 10 -4 mol L -1 for L-dopa and carbidopa, respectively. The detection limits were 2.5 × 10 -5 mol L -1 and 3.7 × 10 -6 mol L -1 for L-dopa and carbidopa, respectively and recoveries of L-dopa and carbidopa from two samples ranged from 98.1 to 103% of the added amount. The relative standard deviations were lower than 2.5% for 1.2 × 10 -4 and 1.2 × 10 -3 mol L -1 of these catecholamines solutions and the results obtained for L-dopa and carbidopa in pharmaceutical formulations using the proposed voltammetric procedure are in close agreement with the labeled values and/or those obtained using an enzymatic method at the 95% confidence level.Keywords: L-dopa, carbidopa, differential pulse voltammetry (DPV), carbon paste electrode modified with lead dioxide 3 On the other hand, catecholamines are present in relatively large amounts in pharmaceutical formulations and much effort has been devoted to the development of simple, rapid, accurate and precise analytical methods. Of those, the most employed methods include spectrophotometry, [4][5][6] high performance liquid chromatography (HPLC) with electrochemical detection [7][8][9][10][11][12][13][14][15] and capillary zone electrophoresis (CZE) with electrochemical detection. [16][17][18][19][20] To the best of our knowledge, there is only one differential pulse voltammetry (DPV) procedure in the literature using a glassy carbon electrode for the determination of L-dopa and a glassy carbon electrode coated with Nafion film for the determination of carbidopa. 21DPV has been demonstrated to be a useful technique for the determination of many molecules of biological importance. 22 The high selectivity, sensitivity, accuracy, pr...

Electrochemical determination of L-dopa at cobalt hexacyanoferrate/large-mesopore carbon composite modified electrode

“…Chemically modified electrodes play an important role in reducing the high overvoltage required for the analyte determination. Some literatures have been reported for the electrochemical determination of L-dopa on chemically modified electrodes [15][16][17][18][19][20][21].…”

Cyclodextrin Host‐Guest Recognition Approach for Simultaneous Quantification and Voltammetric Studies of Levodopa and Carbidopa in Pharmaceutical Products

“…Electrochemical techniques are in general simple, sensitive, accurate and inexpensive analytical tools which have been widely applied to the analysis of pharmaceutical samples [30,31]. Due to serious overlapping of L-dopa and C-dopa signals, only few voltammetric studies utilizing special procedures have been reported for simultaneous determination of these pharmaceuticals [32,33]. Catecholamines can be oxidized on classical elec-trodes such as C, Pt and Au.…”

“…On the other hand, C-dopa was determined between 850 mV and 1100 mV in the presence of L-dopa, by coating the electrode with a Nafion film. Melo et al [33] used a carbon paste electrode modified with lead dioxide immobilized in a polyester resin for simultaneous DPV determination of L-dopa and C-dopa in pharmaceutical formulations. They suggested that the first anodic peak (at 677 mV vs. Ag/AgCl) can be used for the determination of both compounds (Ldopa and C-dopa) and the second one at a potential of 1050 mV for the determination of C-dopa.…”

Electrochemical Determination of L‐Dopa in Mucuna pruriens Seeds, Leaves and Commercial Siddha Product Using Gold Modified Pencil Graphite Electrode

“…Several articles about electrochemical detection of l-dopa on different electrodes have been published. Nafioncoated carbon fiber ultra microelectrodes array [13], carbon paste electrode modified with lead dioxide immobilized in a polyester resin [14], trinuclear ruthenium ammine complex (Ru-red) supported on Y-type zeolites [15], single wall carbon nanotubes [16], electropolymerized 3,3',3'',3'''-tetraaminophthalocyanato-nickel(II) [17], oxovanadium-salen thin film [18], polycarbazole [19]and a disposable electrochemical sensors [20], were used for the detection of l-dopa.…”