Spectrophotometric determination of ternary vanadium(V) complex with 2,4-dihydroxyactetophenonebenzoylhydrazone and pyridine

After the reduction of vanadium(V) with dithionite in the presence of diluted CH3COOH one obtains vanadium(III), which forms a light brown 1:2:1 ternary complex with 2,4-dihydroxyacetophenonebenzoylhydrazone (DHABH) and pyridine (Py). After the extraction to benzene it exhibits maximum absorption at 363 nm. The molar absorptivity and relative standard deviation of the method (for pure vanadium solutions) are 2.83 x 10(4) L mol(-1)cm(-1) and 0.19% for vanadium concentration 1.0 mug mL(-1), respectively. Beer's law holds over the vanadium concentration range: 0-1.5 mug mL(-1). No interferences were observed for a large number of cations, anions and complexing agents. The method is simple, fast, sensitive and highly selective, and has been applied to the determination of vanadium in a variety of synthetic and technical samples with the satisfactory accuracy.