Spectrophotometric method for the determination of vanadium and its application to vanadium steels containing chromium, molybdenum, manganese, copper and nickel

Abstract

Prochlorperazine bismethanesulphonate is proposed as a selective and sensitive reagent for the spectrophotometric determination of vanadium. The reagent forms a red species with vanadium(V) instantaneously in 3.5–6 M orthophosphoric acid medium. A 15-fold molar excess of the reagent is necessary for the full development of the colour intensity. The red species exhibits an absorption maximum at 529 nm with a molar absorptivity of 1.24 × 10⁴ l mol^–1 cm^–1. Beer's law is obeyed over the range 0.1–6.2 p.p.m. of vanadium(V) with an optimum concentration range of 0.3–5.8 p.p.m. The effects of acidity, time, temperature, order of addition of reactants, reagent concentration and interferences from various ions are reported. The method has been used succesfully for the determination of vanadium in vanadium steels containing chromium, molybdenum, manganese, copper and nickel.