Determination of Mn(II) and Co(II) with Arsenazo III

A. B. Zyryanov and A. A. Baykov^*

Belozersky Institute of Physico-Chemical Biology and School of Chemistry, Lomonosov Moscow State University, Moscow, 119992 Russia; fax: (095) 939-3181; E-mail: baykov@genebee.msu.su

^* To whom correspondence should be addressed.

Received April 4, 2001; Revision received April 26, 2001

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Complex formation between Arsenazo III and Mn²⁺ and Co²⁺ at equilibrium has been investigated at pH 7.2, and the stoichiometry and stability of the complexes have been determined. The data indicate that Arsenazo III is suitable for determination of Mn²⁺ and Co²⁺ on the micromolar scale. The dissociation constants of the phosphate complexes of Mn²⁺ and Co²⁺ at pH 7.2 were estimated with Arsenazo III as 3.6 and 10 mM, respectively.

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KEY WORDS: Arsenazo III, manganese (II), cobalt (II), phosphate, complex formation, spectrophotometry

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