Journal of the Brazilian Chemical Society
On-line version ISSN 1678-4790
KARIMI-MALEH, H.; ENSAFI, Ali A. and ENSAFI, Hamid R.. Ferrocenedicarboxylic acid modified carbon paste electrode: a sensor for electrocatalytic determination of hydrochlorothiazide. J. Braz. Chem. Soc. [online]. 2009, vol.20, n.5, pp. 880-887. ISSN 1678-4790. http://dx.doi.org/10.1590/S0103-50532009000500012.
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, kh was calculated (3.38 × 102 cm3 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 electrochemicalsensor for the determination of hydrochlorothiazide in real samples such as drug and urine.
Keywords : ferrocenedicarboxylic acid; hydrochlorothiazide; electrocatalysis; square wave voltammetry.