Analytical Sciences

Abstract − Analytical Sciences, 14(6), 1077 (1998).

Iodometric Amplification Method for the Determinations ofMicrogram Amounts of Manganese(II), Manganese(VII), Chromium(III) andChromium(VI) in Aqueous Solution
Minghao ZHANG* * ,Guoping ZHAN*and Zhanguang CHEN**
*Department of Chemistry, Central South University of Technology,Changsha 410012, P. R. China
**Department of Chemistry and Chemical Engineering, HunanUniversity, Changsha, P. R. China
A simple, rapid and sensitive iodometric amplificationmethod has been developed for the determination of microgram amounts ofMnII, MnVII, CrIII and CrVI.The method is based on the prereductions of MnVII andCrVI with Na2SO3, the oxidations of bothMnII and CrIII in the absence ofNa4P2O7 and the oxidation of onlyMnII in its presence with excess periodate in acetate buffer(pH=3.0), removal of the unreacted periodate by masking with molybdate andthe subsequent titration of liberated iodine after adding iodide. Theindividual amounts of MnII, MnVII, CrIIIand CrVI in different test solutions were successfullydetermined by this method, which offers 20-fold and 12-fold amplificationfor Mn and Cr, respectively. (Keywords: Iodometric amplification, microtitration,chromium(III), chromium(VI), manganese(II), manganese(VII))