极谱法测定钒钛磁铁矿中钒

Determination of vanadium in vanadium-titanium magnetite by polarography

在pH 4.5的HAc-NaAc缓冲溶液中,邻菲罗啉在-0.82V（v.sSCE）处出现一灵敏极谱峰。加入钒,邻菲罗啉极谱峰减小,且减小的峰电流与钒的加入量在0.05~5.0μg/mL范围内呈线性关系,由此建立了极谱法测定钒的新方法。优化了试剂及仪器条件,考察了共存元素的干扰。在优化条件下,钒的检出限为0.004 2μg/mL。测定0.8μg/mLV（,除Fe,Ti,Mn外,钒钛磁铁矿中其它元素没有干扰。Fe,Ti可以通过控制溶液的pH值用沉淀方法分离,Mn和溶液中残留Fe,Ti可加入F-络合消除其对钒测定的干扰。方法用于钒钛磁铁矿标准样品中钒的测定,测定值与认定值相符,测定结果的相对标准偏差小于1.1%。

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 %.