安替吡啉偶氮分光光度法测定铌(Ⅴ)

Determination of niobium(Ⅴ) by antipyrinylazo spectrophotometry

合成了5-（4-安替吡啉偶氮）水杨醛（AASA）,探讨了试剂与铌（Ⅴ）的显色反应条件,建立了测定铌（Ⅴ）的光度分析新方法.实验表明,在pH 2.0的HCl-KCl缓冲体系中,铌（Ⅴ）与AASA形成摩尔比为1∶1的浅黄色络合物,最大吸收波长为460 nm.铌（Ⅴ）的质量浓度在0～1.6 μg/mL符合比尔定律,其回归方程为A=0.077 79＋0.012 91ρNb（μg/25 mL）,相关系数r=0.999 6,表观摩尔吸光系数为3.0×104 L·mol-1·cm-1.将AASA分光光度法应用于铁-铌合成溶液中铌的测定,结果与氯磺酚S法一致,相对标准偏差为1.6％～1.7％.

5-（4-antipyrinylazo） salicylaldehyde （AASA） were synthesized, and the conditions for its chromogenic reaction with niobium（v） were investigated. Thus, a novel method for the determination of niobium（V） was established by spectrophotometry. The experimental results showed that niobium（V） and AASA could form a pale yellow complex with molar ratio of 1 ： 1 and maximum absorption wave- length of 460 nm in pH 2.0 HCl-KCl buffer solution. Beer＇s Law was complied within the concentra- tion range of 0-1.6 μg/mL for niobium（Ⅴ） with linear regression equation of A=0. 077 79＋0. 012 91ρNb （μg/25 mL） and r of 0. 999 6,and the apparent molar absorptivity was 3.0×10^4 L· mol ^-1 . cm 1 AASA spectrophotometry was applied to the determination of niobium in iron-niobium synthetic solu- tion, and the results were consistent with those obtained by sulfochlorophenol S method with relative standard deviation of 1.6 %-1.7 Y00.