Ferrocenedicarboxylic acid modified carbon paste electrode: a sensor for electrocatalytic determination of hydrochlorothiazide

Abstract

A oxidação eletrolítica de hidroclorotiazida foi estudada usando-se eletrodo de pasta de carbono modificado com ácido ferrocenodicarboxílico. Voltametria cíclica e cronoamperometria foram usadas para investigar a possibilidade de aplicação do ácido ferrocenodicarboxílico como mediador na oxidação eletrocatalítica de hidroclorotiazida em solução aquosa. A oxidação de hidroclorotiazida ocorre em um potencial, aproximadamente, 300 mV menos positivo do que com o eletrodo de pasta de carbono não modificado, em pH 9,0. A constante de velocidade da reação catalítica, k h , foi calculada (3,38 × 10 2 cm 3 mol -1 s -1) usando-se cronoamperometria. Em condições ótimas, a corrente de pico da oxidação eletrocatalítica da hidroclorotiazida mostrou dois intervalos dinâmicos lineares com limite de detecção de 0,037 μmol L -1 de hidroclorotiazida. Os intervalos de calibração lineares ocorreram entre 0,08-5,8 μmol L -1 e 5,8-500,0 μmol L -1 de hidroclorotiazida, usando-se voltametria de onda quadrada. Finalmente, o método proposto foi também examinado quanto à seletividade, simplicidade e precisão na determinação de hidroclorotiazida em amostras reais como droga e urina.The electrocatalytic oxidation of hydrochlorothiazide has been studied by ferrocenedicarboxylic acid modified carbon paste electrode. Cyclic voltammetry and chronoamperometry were used to investigate the suitability of ferrocenedicarboxylic acid as a mediator for the electrocatalytic oxidation of hydrochlorothiazide in aqueous solution. The oxidation of hydrochlorothiazide occurs at a potential about 300 mV less positive than with the unmodified carbon paste electrode at pH 9.0. The catalytic reaction rate constant, k h was calculated (3.38 × 10 2 cm 3 mol -1 s -1 ) using chronoamperometry. Under the optimized conditions, the electrocatalytic oxidation peak current of hydrochlorothiazide showed two linear dynamic ranges with a detection limit of 0.037 μmol L -1 hydrochlorothiazide. The linear calibration ranges were between 0.08-5.8 μmol L -1 and 5.8-500.0 μmol L -1 hydrochlorothiazide using square wave voltammetric method. Finally, the proposed method was also examined as a selective, simple and precise electrochemical sensor for the determination of hydrochlorothiazide in real samples such as drug and urine.Keywords: ferrocenedicarboxylic acid, hydrochlorothiazide, electrocatalysis, square wave voltammetry IntroductionHydrochlorothiazide (HCTZ) (6-chloro-7-sulfamoyl-3,4-dihydro-1,2,4-benzothiadiazine1,1-dioxide) has gained attention because it is a benzothiazide diuretic that acts directly on the kidney by increasing the excretion of sodium chloride and water and, to a lesser extent, that of potassium ions. HCTZ is an antihypertensive substance and improves the action of other hypotensive substances, allowing a decrease in the dose of those below the level where these substances present secondary effects. Novello and Sprague observed the diuretic effect of thiazides with chlorothiazide in 1957.1 HCTZ is well absorbed, is shortly bound to plasma proteins, and ma...

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Electrocatalytic determination of cysteamine using multiwall carbon nanotube paste electrode in the presence of 3,4-dihydroxycinnamic acid as a homogeneous mediator

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