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High sensitive determination of trace amount of cobalt by catalytic adsorptive stripping voltammetry
S. Bahrami S. Abbasi Y. A. Ghorbani A. A. Miran-Beigi 《Russian Journal of Electrochemistry》2009,45(2):208-214
A very sensitive and selective catalytic adsorptive cathodic stripping procedure for trace measurements of cobalt is presented.
The method is based on adsorptive accumulation of cobalt-CCA (calcon carboxylic acid) complex onto a hanging mercury drop
electrode followed by reduction of the adsorbed species by voltammetric scan using differential pulse modulation. The reduction
current is enhanced catalytically by nitrite. The effect of various parameters such as pH, concentration of CCA, concentration
of nitrite, accumulation potential and accumulation time on the selectivity and sensitivity were studied. The optimum condition
for the analysis of cobalt, include pH 5.2 (Acetate buffer), 2.1 μM clacon carboxylic acid, 0.032 M sodium nitrite and an
accumulation potential of 0.05 V (versus Ag/AgCl). Under these optimum conditions and for an accumulation time of 60 s, the
measured peak current at −0.480 V is proportional to the concentration of cobalt over the entire concentration range tested
0.003–2.0 ng ml−1 with a detection limit of 1 pg ml−1 for an accumulation time of 60 s and 2.0–10.0 ng ml−1 for an accumulation time of 40 s. The relative standard deviations for ten replicate measurement of 0.5 ng ml−1 of cobalt were 3.1%. The main advantage of this new system is the microtrace Co(II) determination by ASV. The method was
applied to determination of cobalt in a water sample and some analytical grade salts with satisfactory results.
Published in Elektrokhimiya in Russian, 2009, Vol. 45, No. 2, pp. 221–228.
The article is published in the original. 相似文献
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Some aspects of the polarographic reduction of sodium 1-(2-hydroxy-1-naphthylazo)-2-naphthol-4-sulphonate (trivial name: calcon or Eriochrome Blue Black R), as observed when using differential pulse polarography (d.p.p.) and alternating current polarography (a.c.p.), are described, as well as the polarographic behaviour of this compound in the presence of some metal ions. The peak that appears in the d.p.-polarogram due to the reduction of the cobalt (II) complex is the basis of a method for the determination of very small trace amounts of cobalt(II). The proposed procedure is rather selective (Ni(II) interferes, Mn(II) does not) and has a limit of detection of 7 g 1–1 (minimum amount which can be determined 0.6 g Co(II)). 相似文献
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