Simultaneous determination of captopril and thioguanine in pharmaceutical compounds and blood using cathodic adsorptive stripping voltammetry

Abstract

Apresentamos um procedimento altamente seletivo e sensível para a determinação simultânea de captopril e de tioguanina baseado em processo de redissolução catódica adsortiva dos complexos de Cu(I)-captopril e de Cu(I)-tioguanina em um eletrodo gotejante de mercúrio. Captopril e tioguanina foram pré-concentrados na superfície da gota do eletrodo de mercúrio usando Cu(II) como sensor e tempo de acumulação igual a 90 s. Em seguida, os complexos pré-concentrados foram analisados por voltametria adsortiva de pulso diferencial catódica. O efeito de vários parâmetros na sensibilidade, tais como, pH, concentração de cobre, potencial de acumulação, tempo de acumulação e velocidade de varredura, na sensibilidade do método foram estudados. As condições ótimas para a determinação simultânea de captopril e de tioguanina foram: pH = 3,5, concentração de cobre(II) = 45,0 ng mL -1 , potencial de acumulação = -0,10 V e velocidade de varredura = 60 mV s -1 . Nas condições ótimas e tempo de acumulação igual a 90 s, os picos de corrente medidos em torno de -0,15 V e -0,40 V (vs. Ag/AgCl) foram proporcionais às concentrações de tioguanina e de captopril nas faixas de 0,15-180 e 0,5-100 nmol L -1 . Os limites de detecção para tioguanina e captopril foram 0,08 e 0,3 nmol L -1 , respectivamente. Os desvios padrões relativos para cinco replicatas de 20,0 nmol L -1 de captopril e de tioguanina foram 2,5% e 2,1%. O método para a determinação de captopril e de tioguanina foi testado em amostras de misturas sintéticas, farmacêuticas e em soro humano, apresentando resultados satisfatórios.A reliable, highly selective and sensitive procedure is presented for simultaneous determination of captopril and thioguanine based on cathodic adsorptive stripping of Cu(I)-captopril and Cu(I)-thioguanine complexes on a hanging mercury drop electrode. Captopril and thioguanine were preconcentrated onto the surface of hanging mercury drop electrode using Cu(II) as a suitable probe, with accumulation time of 90 s. Then the preconcentrated complexes were analyzed by cathodic stripping differential pulse voltammetry. The effect of various parameters such as pH, concentration of copper, accumulation potential, accumulation time and scan rate on the sensitivity were studied. The optimum conditions for simultaneous determination of captopril and thioguanine include pH=3.5, 45.0 ng mL -1 copper(II) concentration, accumulation potential of -0.10 V and scan rate of 60 mV s -1 . Under the optimum conditions and for an accumulation time of 90 s, the measured peak currents at about -0.15 V and -0.40 V (vs. Ag/AgCl) are proportional to the concentrations of thioguanine and captopril over the ranges of 0.15-180 and 0.5-100 nmol L -1 , respectively. The limits of detection are 0.08 and 0.3 nmol L -1 for thioguanine and captopril, respectively. The relative standard deviations for five replicate analyses of 20.0 nmol L -1 captopril and thioguanine are 2.5% and 2.1%, respectively. The method was applied to the determination of captopril and thioguanine in synthetic mixed sa...

Indirect spectrophotometric method for determination of captopril using Cr(VI) and diphenylcarbazide

“…It is a well known drug applied in the treatment of hypertension, coronary heart disease and congestive heart failure following myocardial infarction as well as in diabetic nephropathy. 1,2 Many analytical methods have been developed for CP determination, such as visual titrimetry, 3 electrometric methods, [4][5][6][7][8] capillary electrophoresis, 9 capillary isotachophoresis, 10 flow injection analysis, 11 and chromatographic methods. [12][13][14][15][16][17] The most widely used technique for captopril determination is high-performance liquid-chromatography.…”

Simple Real-time Voltammetric Method for Captopril Determination in Pharmaceutical Formulation

“…The simple activation procedure used to make the modified electrode is an obvious advantage of the sensor. Acidic conditions were best suited for CAP determination with a detection limit of 2.34·10 -5 M. No gas purging for dissolved oxygen removal from the sample solution [8] and/or preconcentration time as in stripping methods [33,34] are needed. The method is also faster than chromatographic ones.…”

Voltammetric/amperometric screening of compounds of pharmacological interest

“…Explicit application for determination of drugs in human urine (El-Maali 2000, Garcia-Fernandez et al 2000, Fernandez Torres et al 2002, Shih et al 2002, Hilali et al 2003, Morais et al 2003, Reddy and Sreedhar 2003, Razak 2004, Ensafi and Hajian 2008a,b, Daneshgar et al 2009a,b, Muralidharan et al 2009, Tyszczuk and Korolczuk 2009a,b, Behpour et al 2010, Ensafi et al 2011, Zayed 2011, Gopu et al 2012, Khaskheli et al 2012, Gupta et al 2013a,b, Lakshmi and Vedhi 2013, Švorc et al 2013) and human serum , Sreedhar et al 2001, Altinoz and Nemutlu 2002, El-Hefnawy et al 2003, Coruh and Ozkan 2006, Wang et al 2006, Altun et al 2007, Beltagi et al 2007aEl-Desoky 2009, Alarfaj 2013, Arvand and Gholizadeh 2013 are numerous. In contrast, few reports are addressed to determinations in cerebrospinal fluid (Jimenez Palacios et al 2003), bovine muscle and serum (Ammida et al 2004, Barbosa et al 2006, and milk (Billova et al 2003).…”