Trace determination of zirconium using anodic adsorptive voltammetry at a carbon paste electrode modified with multi-walled carbon nanotubes

A carbon paste electrode modified with multi-walled carbon nanotubes (MWCNT) was prepared and the determination of ultra trace amount of zirconium based on the anodic adsorptive voltammetry of the zirconium-calcium-alizarin red S mix-polynuclear complex is described in this paper for the first time. The results showed that the sensitivity and the selectivity of the method are excellent. The second derivative linear scan voltammograms of the complex were recorded by polarographic analyzer from 200 to 1200 mV (vs. SCE) and it was found that the complex can be adsorbed on the surface of the electrode, yielding a peak at about 840 mV, corresponding to the oxidation of ARS in the complex. The peak current increases linearly with Zr (IV) concentration in the range of 6.0×10⁻¹²-6.0×10⁻¹¹ mol·L⁻¹ (accumulation time 120 s), 6.0×10⁻¹¹-2.0×10⁻⁹ mol·L⁻¹ (accumulation time 90 s) and 2.0×10⁻⁹-1.0×10⁻⁷ mol·L⁻¹ (accumulation time 60 s) and the detection limit (S/N = 3) is 2.0×10⁻¹² mol·L⁻¹ (accumulation time 180 s). The procedure has been successfully applied to the determination of zirconium in the ore samples. Supported by the Project of Science and Technology Fund of Hengyang City (Grant No. 2007KJ001), the Project of Scientific Research of Hengyang Normal University (Grant No. 07A19), the Key Project of Chinese Ministry of Education (Grant No. 206104) and the Multidiscipline Scientific Research Foundation of Xiangtan University (Grant No. 05IND08)