改进的磷钨酸光度法测定水溶液中的钒(Ⅳ)和总钒

Improvenment determination of the oxidovanadium( Ⅳ ) and total vanadium in the solution by modified phosphorus-tungsten-vanadium avid spectrophotometry

应用改进的磷钨酸光度法测定了样品中总钒和钒(Ⅳ)。在10%HCl介质中,一定体积的待测溶液中添加10%(V:V)H_3PO_4和20%(V:V)的Na_2WO_4·2H_2O(50 g/L)溶液,于30℃下显色30 min。方法的线性范围是0~30 mg/L,线性相关系数R^2=0.9992,相对标准偏差(n=12)为1.2%。并确定了天然水溶液中常见离子干扰钒测定的最大允许量。在此基础上,调节溶液的pH>4,测定V(Ⅳ)。改进后方法测V(Ⅳ)的线性范围为0~5 mg/L,相关系数R^2=0.9998。应用测定自来水和河水中V(Ⅳ)。

In this paper, the phosphorus-tungsten acid spectrophotometry for determination of Vanadium（ Ⅳ） in the samples,which indirect measured the total and tetravalent Vanadium. In 10% hydrochloric acid medium, the 10% phosphoric acid and 20% sodium tungstate solution（50 g/L） were added to the unmeasured liquids, which colored for 30 min under 30℃. The linear range was 0 to 30 mg/L that the coefficient correlation of curve was R2 = 0. 9992, and relative standard deviation （RSD,n = 12） was 1.2%. What is more,the cap of common ions in the natural aqueous solution that disturbed vanadium determination were identified. On the basis of this method, adjusting the solution pH 〉 4 to determinate tetravalent vanadium. The linear range of improvement method was 0 ～ 5 mg/L, which the coefficient correlation of curve was R2 = 0. 9998. The method for the determination of the oxidovanadium in the tap water and river had achieved satisfactory results.