Synthesis and Application of 3-Hydroxy-2-[3-(4-Methoxyphenyl)-1-Phenyl-4-Pyrazolyl]-4-Oxo-4h-1-Benzopyran for Extractive Spectrophotometric Determination of Vanadium (V)

Rajesh Agnihotri; Nivedita Agnihotri; Vikas Kumar; Raj Kamal

Abstract

Synthesis and Application of 3-Hydroxy-2-[3-(4-Methoxyphenyl)-1-Phenyl-4-Pyrazolyl]-4-Oxo-4h-1-Benzopyran for Extractive Spectrophotometric Determination of Vanadium (V)

3-Hydroxy-2-[3-(4-methoxyphenyl)-1-phenyl-4-pyrazolyl]-4-oxo-4H-1-benzopyran (HPMEPB) has been found to form a green 1:3 (M:L) complex with vanadium(V) in weakly acidic medium at 0.02-0.12 M CH₃COOH. The complex was extracted into carbon tetrachloride and showed absorption maximum at 408-417 nm, molar absorptivity, Sandell’s sensitivity and detection limit of the method were calculated to be 2.70 × 10⁴ l mol^-1 cm^-1, 0.0018 μg V cm-2 and 7.913 × 10^-5 gl^-1, respectively at 415 nm. Linear regression equation was Y=0.527 X+0.004, with correlation coefficient, r=0.9951. Beer’s law was obeyed over the vanadium concentration range of 0-2.2 μg ml^-1. Effect of large number of cations, anions and complexing agents was studied. Out of these, ascorbic acid, oxalate and hydrogen peroxide interfered seriously. The present method is simple, rapid, sensitive and has been satisfactorily applied to the determination of vanadium in various synthetic and technical samples.