Estudo polarográfico sobre a determinação de Fe(III) utilizando-se a técnica da polarografia de pulso diferencial

Abstract

Recebido em 20/10/00; aceito em 4/3/01 POLAROGRAPHIC STUDY ABOUT THE DETERMINATION OF Fe(III) USING THE TECHNIQUE OF DIFFERENCIAL PULSE POLAROGRAPHY. A differential pulse polarographic study with the objective to determine iron (III) in presense of copper (II) in a supporting electrolyte based on citrate-EDTA was made. The best experimental conditions found were a supporting electrolyte of citrate 0.25 mol L-1 , EDTA 0.050 mol L-1 and KNO 3 0.50 mol L-1 , pH 5.00. In this media iron (III) showed a polarographic peak in-0.08 V and the copper (II) in-0.34 V, both vs. Ag/AgCl (saturated KCl). Thus, a analytical method was developed and applied to determine iron (III) in brass alloy, a matrix were copper is in large excess over iron. The results obtained showed no interference of copper in the iron determination. The value of 0.21% of iron in the sample alloy composition was obtained and the method was validated by atomic absortion and recovery test, and the results exhibited a good agreement with the proposed method.