Square wave voltammetry in the determination of Ni2+ and Al3+ in biological sample.

Anal Sci. 2008;24(11):1443-7.
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Square wave voltammetry in the determination of Ni2+ and Al3+ in biological sample.

Paulino AT, Vargas AM, Santos LB, Nozaki J, Muniz EC, Tambourgi EB.

Universidade Estadual de Campinas, Departamento de Sistemas Químicos, Faculdade de Engenharia Química, Campinas-São Paulo, Brazil. atpaulino10@gmail.comIn this contribution, the amounts of Ni (nickel) and Al (aluminum) in tilapias (Oreochromis niloticus) were determined using square wave voltammetry (SWV) with glassy carbon working microelectrode with a mercury thin film, platinum counter electrode, and Ag/AgCl reference electrode. Ni was studied through the formation of the dimethylglyoxime-Ni (Ni-DMG) complex, while Al was studied through the formation of the Alizarin R-Al complex. The detection limit found for Ni-DMG and Alizarin R-Al complexes were 1.70 x 10(-7) and 1.0 x 10(-8) mol L(-1), respectively. The voltammetric anodic curves for the Alizarin R-Al complex were recorded over the potential range from -0.8 to -0.05 V while the voltammetric cathodic curve for the Ni-DMG complex was recorded over the potential range from -0.7 to -1.2 V. These methods detected low concentrations of Ni and Al in biological samples efficiently.

Publication Types:
Research Support, Non-U.S. Gov't

PMID: 18997373 [PubMed - indexed for MEDLINE]

Determination of losartan and triamterene in pharmaceutical compounds and urine using cathodic adsorptive stripping voltammetry.

Anal Sci. 2008;24(11):1449-54.
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Determination of losartan and triamterene in pharmaceutical compounds and urine using cathodic adsorptive stripping voltammetry.

Ensafi AA, Hajian R.

Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran. Ensafi@cc.iut.ac.irA 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 (beta) for losartan-Cu(II), number of transfer electrons (n), transfer coefficients (alpha) and number of proton transfers were also estimated.

Publication Types:
Research Support, Non-U.S. Gov't

PMID: 18997374 [PubMed - indexed for MEDLINE]