Determination of vanadium in petroleum products by a catalytic method

Abstract

The oxidation of chlorpromazine by potassium bromate is a slow process, and vanadium(V) has a catalytic effect on the reaction rate. The reaction is followed spectrophotometrically by measuring the increase in absorbance at 525 nm. The slope of the absorbance versus time graph is used as a measure of the reaction rate. Under the optimum experimental conditions (2 M H₃PO₄, 8 × 10^–5M chloropromazine and 3 × 10^–4M potassium bromate) vanadium(V) is determined between 10 and 400 ng ml^–1. The precision and accuracy of the method and the influence of 46 foreign ions were studied. The procedure was applied to the determination of vanadium in petroleum products with excellent results.