Direct complexometric determination of aluminium and moderate to low amounts of titanium and iron using tartaric acid as a de-masking agent

Abstract

A critical study has been made on the masking of titanium and de-masking of the TiO-EDTA (ethylenediaminetetraacetic acid) complex with tartaric acid. It reveals that tartaric acid de-masks TiO-EDTA selectively and quantitatively with the release of EDTA at pH 5.3 from a solution at 60–70 °C containing TiO-EDTA, Al-EDTA and Fe-EDTA complexes. The release of EDTA from Al-EDTA is, however, effected by the usual practice of de-masking with sodium fluoride or ammonium fluoride. Based on these observations, procedures are given for the direct complexometric determination of aluminium, titanium and iron present in the same analyte by stepwise indirect titration with EDTA, which does not involve prior separation of the metals. The method is, therefore, very simple, rapid and accurate and has been applied successfully to determine aluminium and moderate to low amounts of titanium and iron present in common aluminosilicate materials. Results for the determinations compare favourably with both the certified values and values obtained by other standard methods.