Selective and sensitive spectrophotometric determination of total vanadium with hydrogen peroxide and 4-(2-pyridylazo)-resorcinol

A selective and sensitive method for the spectrophotometric determination of the total amount of vanadium based on the reaction with 4-(2-pyridylazo)-resorcinol, PAR, and hydrogen peroxide is proposed. The formed complex shows maximum absorbance at 542 nm with molar absorptivity=1.85 x 10(4) l mol(-1) cm(-1) in the range from 0.01 to 0.5 mol l(-1) of sulfuric acid and obeys the Beer's law up to 3.0 mu g ml(-1) of vanadium. The limit of detection of the method is 0.0028 mu g ml(-1) (3 sigma). The analytical method can be directly applied for the determination of vanadium in steels providing good results. Prior separation of some interfering elements is not necessary. The characteristics of the method, i.e. simplicity, selectivity, sensitivity and rapid calibration, make it specially suitable for routine analysis. (C) 1999 Elsevier Science B.V. All rights reserved.