Simultaneous Spectrophotometric Determination of Germanium(IV) and Silicon(IV) in Their Mixtures Using the Difference in Reaction Rates of Formation of Molybdenumas Blues

Abstract

A kinetic method has been presented for simultaneous spectrophotometric determination of germanium(N) and silicon(W) in their mixtures. This method was bqsed on- the difference in ieaction rates of formation of molybdenum blues which were produced by reducing the heteropoly acids of the two elements; it wasfound that the initial rate of gerrpanomglybdenun Slute formation was much lowerthan that of silicomolybdenum blue formation under certain conditions. Analysis of mixtures of germanium(N) and silicon(W) was accomplished by using the following equations:[Ge]e (ptg/ml) = -2.31 ve+7.20 ASiP u9/m, =1, 47, Ve-o, 58 Awhere vc is the initial rate of molybdenum blue formation expressed in absorbance unit and A is the final absorbance of reacting solution at 700 nm. Results of analysis of mixtures containing O.50 v2.50 ptg/ml of germanium(va) and O.040.vO.200 ug/ml of silicon(W) are given inTable, 1. Silver, iron(III), vanadium(V), copper(II), phosphorus(V)and arsenic(V)ions interfered with rather seriously. lt was also found that O.12-vO.80 u/ml of silicon(V) could be determined in the presence of O.Ol ug/ml of germanium(W) by measuring only the initial rate of silic, omolybdenum blue formation (Table 2).