Novel voltammetric methods for vanadium determination by exploitation of catalytic adsorptive vanadium-chloranilic acid-bromate system

A new differential pulse polarographic (DPP) and catalytic adsorptive stripping voltammetric (CAdSV) methods for the determination of vanadium(V) have been developed. The CAdSV method is based on the adsorptive accumulation of the vanadium-chloroanilic acid (CAA) complex on the surface of a HMDE and the utilization of the catalytic reaction with BrO3-. The optimal CAdSV vanadium(V) response was obtained in (0.04 / 0.2) M acetic buffer at pH 4.5-4.8 in the presence of (2.0 / 4.0) x 10-5 M CAA and (5.0 / 10.0) x 10-3 M KBrO3 with an accumulation potential of (-0.10 / -0.15) V and accumulation time of (80 / 120) s. The sensitivity of the CAdSV was 42.7 nA nM-1 and the linearity range amounted from 2 x 10-10 up to 5 x 10-8 M for 100 s of accumulation. The R.S.D. was 4.5% at the 1.0 x 10-9 V(V) level. The detection limits were found to be 2.8 x 10-9 M for DP polarography and 9 x 10-12 M for CAdSV with 100 s of accumulation. Possible interferences by Sb(III), Pb(II), Cu(II), Cd(II), Fe(III), Bi(III), Sn(II), Sn(IV), U(VI), Mo(VI) and surface active substances were evaluated. The results of the determination of V(V) in certified reference material water sample showed good reproducibility (R.S.D. = 3.4%) and reliability of the elaborated CAdSV method