铌(Ⅴ)-桑色素-吐温-80反应体系的吸光光度法测定铌的研究

STUDY ON THE ABSORPTIOPHOTOMETRIC DETERMINATION OF NIOBIUM BY THE REACTION SYSTEM OF Nb(Ⅴ)-MORIN-TWEEN-80

摘要: 在盐酸介质中,铌(Ⅴ)与桑色素和吐温-80形成多元络合物,其表观摩尔吸光系数为(ε430)=7.90×104L·mol-1·cm-1,相关系数为0.998 8,铌量在0-0.40 mg·L-1范围内符合比耳定律,用丹宁沉淀法分离Fe3+、Al3+、V(Ⅴ)、W(Ⅶ)、Cr(Ⅵ)、Mn2+等干扰离子,应用于地质、合金样品中微量铌的测定,其相对标准偏差≤4.0%(n=8).

Abstract: A method of spectrophotometric determination of trace amounts of Nb was described.A ternary complex of Nb(Ⅴ) with 3,5,7,2′,4′-pentahydroxyflavone (morin) and Tween 80 was formed in HCl medium.Beer′s law was obeyed in range of Nb(Ⅴ) concentration of 0-0.40 mg·L-1 with a correlation coefficient of 0.998 8.Molar absorptivity of the complex was 7.90×104L·mol-1·cm-1 at λmax 430 nm.After separation of interfering Fe(Ⅲ),Al(Ⅲ),V(Ⅴ),W(Ⅶ),Cr(Ⅵ) and Mn(Ⅱ) by precipitation with tannin,Nb was successfully determined in complicated geological samples and alloy samples,with RSD≤4.0% (n=8).