Determination of vanadium in vanadium-titanium magnetite by polarography

In HAc-NaAc buffer solution at pH 4.5,phenanthroline showed a sensitive polarographic peak at-0.82V(vs.SCE).After adding vanadium,the polarographic peak was reduced.Meanwhile,the reduction of peak current had linearity to the addition amount of vanadium in the range of 0.05-5.0 μg/mL.Based on this,a new determination method of vanadium by polarography was established.The reagents and instrumental conditions were optimized.The interference of coexisting elements was investigated.Under the optimal conditions,the detection limit of vanadium was 0.004 2 μg/mL.During the determination of 0.8 μg/mL vanadium(V),the coexisting elements in vanadium-titanium magnetite had no interference expect for Fe,Ti and Mn.Fe and Ti could be separated by precipitation method through controlling pH of the solution.The interference of Mn and residual Fe and Ti in solution could be eliminated by adding F-.The proposed method has been applied to the determination of vanadium in vanadium-titanium magnetite certified reference materials.The results were consistent with the certified values,and the relative standard deviations(RSD) were less than 1.1 %.