Spectrophotometric and potentiometric studies of oxovanadium(IV) chelates with Eriochrome black T and Solochrome black 6 BN

Abstract

Vanadium(IV) forms colored chelates with Erio T and Solo 6 BN ( λ max 570 and 580 nm, respectively) at pH 3.8. The composition MR 2 of the chelates investigated was established by continuous variation, mole ratio, slope ratio and straight-line methods spectrophotometrically. For photometric determination of V(IV) with these reagents Sandell's sensitivity, Beer's law range, Ringbom optimum range were also determined. Bjerrum and Calvin potentiometric titration technique was employed to determine the stepwise formation constants of each system. For V(IV)-Erio T system values of log K 1 = 14.4, log K 2 = 10.9 and for V(IV)-Solo 6 BN system log K 1 = 16.1, log K 2 = 11.8 were obtained.