Analytical Sciences

Electroanalysis and Simultaneous Determination of 6-Thioguanine in the Presence of Uric Acid and Folic Acid Using a Modified Carbon Nanotube Paste Electrode

Hadi BEITOLLAHI,* Jahan-Bakhsh RAOOF,** and Rahman HOSSEINZADEH***

*Environment Department, Research Institute of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman, Iran
**Electroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran
***Department of Organic Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran

The present work describes the preparation and characterization of a carbon nanotube paste electrode modified with 2,7-bis(ferrocenyl ethyl)fluoren-9-one (2,7-BF). This electrode showed an efficient catalytic activity for the electro-oxidation of 6-thioguanine (6-TG), which leads to lowering 6-TG overpotential by more than 610 mV. Also, the values of catalytic rate constant (k = 2.7 × 10³ mol⁻¹ L s⁻¹), and diffusion coefficient (D = 2.7 × 10⁻⁵ cm² s) were calculated. In 0.1 M phosphate buffer solution of pH 7.0, the oxidation current increased linearly with two concentration intervals of 6-TG, one is 0.06 to 10.0 μmol L⁻¹ and the other is 10.0 to 160.0 μmol L⁻¹. The detection limit (3σ) obtained by differential pulse voltammetry (DPV) was 22.0 nmol L⁻¹. DPV was used for simultaneous determination of 6-TG, uric acid (UA) and folic acid (FA) at the modified electrode, and for quantification of 6-TG, UA and FA in some real samples by the standard addition method.

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