Analytical Sciences
Online ISSN : 1348-2246
Print ISSN : 0910-6340
ISSN-L : 0910-6340
Original Papers
Determination of Losartan and Triamterene in Pharmaceutical Compounds and Urine Using Cathodic Adsorptive Stripping Voltammetry
Ali Asghar ENSAFIReza HAJIAN
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2008 Volume 24 Issue 11 Pages 1449-1454

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Abstract

A square-wave voltammetric procedure for the electroanalytical determination of losartan and triamterene in Britton-Robinson buffer (pH 3.0, 0.1 mol L-1) as a supporting electrolyte containing 30 ng mL-1 of copper ions was developed. Opposite to the case of triamterene, losartan can not be reduced at a mercury electrode alone, but a new peak appears at -0.25 V in the presence of copper due to the formation of a complex between copper(II) and losartan. An accumulation potential of -0.30 V during 80 s for the prior adsorption of losartan-copper(II) and triamterene on the electrode surface was used. The response of the system was found to be linear in the range of 30.0 - 270.0 nmol L-1 for losartan and two linear dynamic ranges containing 0.5 - 200.0 and 200.0 - 400.0 nmol L-1 of triamterene. The limits of detections were 9.7 and 0.3 nmol L-1 for losartan and triamterene, respectively. The relative standard deviations for five replicate analyses of 100.0 and 10.0 nmol L-1 losartan and triamterene were 5.5%. Applicability to assay the drugs in urine and pharmaceutical formulations was illustrated with satisfactory results. The direct-current polarography of triamterene indicates that the reduction of a related drug is strongly dependent on the pH of the solution. A linear segment was found with slope value of -63.6 mV pH-1 in the pH range of 2.0 - 6.0. The stoichiometry and complex formation constant (β) for losartan-Cu(II), number of transfer electrons (n), transfer coefficients (α) and number of proton transfers were also estimated.

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© 2008 by The Japan Society for Analytical Chemistry
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