Iodometric Amplification Method for the Determinations of Microgram Amounts of Manganese(II), Manganese(VII), Chromium(III) and Chromium(VI) in Aqueous Solution

Abstract

A simple, rapid and sensitive iodometric amplification method has been developed for the determination of microgram amounts of Mn^II, Mn^VII, Cr^III and Cr^VI. The method is based on the prereductions of Mn^VII and Cr^VI with Na₂SO₃, the oxidations of both Mn^II and Cr^III in the absence of Na₄P₂O₇ and the oxidation of only Mn^II in its presence with excess periodate in acetate buffer (pH=3.0), removal of the unreacted periodate by masking with molybdate and the subsequent titration of liberated iodine after adding iodide. The individual amounts of Mn^II, Mn^VII, Cr^III and Cr^VI in different test solutions were successfully determined by this method, which offers 20-fold and 12-fold amplification for Mn and Cr, respectively.