Chemical analysis of rutile - a pyrocatechol violet spectrophotometric procedure for the direct microdetermination of zirconium

The ZrO₂ content of rutile is determined spectrophotometrically by a direct pyrocatechol violet procedure. The sample is decomposed by potassium pyrosulfate fusion in a transparent quartz crucible, and a sulfuric acid solution of the melt is used for the determination at a pH of 5.1. Of the elements commonly present in rutile, only titanium and niobium occur in concentrations large enough to interfere. Titanium and niobium interference is overcome by adding the titanium and niobium contents of the sample to the standard zirconium solutions used for the standard zirconium curve. The absorbance is measured at 570 nm. Beer's law is obeyed within the range of 0.05-1.50 ppm ZrO₂. In the presence of 50 ppm TiO₂, the range is 0.15-1.50 ppm ZrO₂ . The tolerances of 47 elements were determined. The sensitivity is 0.0058 ug Zr/cm² . The variables in the method were studied, and typical results are given for commercial rutile concentrates.