HIGHLY SENSITIVE SPECTROPHOTOMETRIC KINETIC DETERMINATION OF VANADIUM BY CATALYTIC EFFECT ON THE GALLOCYANINE-BROMATE REACTION

A simple kinetic spectrophotometric method was developed for the determination of traces of vanadium present in petroleum, food and steel. The method is based on the catalytic effect of vanadium on the oxidation of gallocyanine by bromate at a pH of 4.0. The decrease in absorbance of gallocyanine at 620 nm at a fixed time of 4.5 min from initiation of the reaction is proportional to the concentration of V(V) for the range of 0.010-500 ng.ml(-1). The limit of detection is 0.0005 ng.ml(-1). The relative standard deviation for ten replicate measurements of 1.00 ng.ml(-1) of vanadium is 1.7%. The interferences of ions could be eliminated by a simple procedure.