新试剂2－（5－硝基－2－吡啶偶氮）－5－二乙氨基苯酚与铌配合物的分光光度法研究

Spectrophotometric study on Nb(V)complex with a new chromogenic reagent 2-(5-nitro2-pyridylazo)-5-diethylaminophenol

研究了新试剂２－（５－硝基－２－吡啶偶氮）－５－二乙氨基苯酚（５－ＮＯ２－ＰＡＤＡＰ）与Ｎｂ（Ｖ）分光光度性质。在含０．０８ｍｏｌ／ＬＨ２ＳＯ４的水－乙醇介质中，Ｎｂ（Ｖ）能与５－ＮＯ２－ＰＡＤＡＰ进行灵敏的显色反应，形成１：１的深色配合物，最大吸收波长为６１０ｎｍ，摩尔吸光系数为９．５９×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，铌在０～５０μｇ／２５ｍＬ范围内服从比尔定律，本法体系简单，操作简便快速；选择性好；常见元素允许量较大，８倍量的钽存在不产生干扰。用于矿样中微量铌的测定，结果令人满意。

This paper studied the spectrophotometric properties of the complex of Nb(V) with the new chromogenic reagent, 2-(5-nitro-2-pyridylazo)-5-diethylam inopbenol (5-NO2-PADAP). In aqueous ethanol containing 0.08mol/L H2SO4, Nb(V) can react with 5-NO2-PADAP sensitively to form a 1:1 deep colored complex. The maximum absorption wavelength of niobium complex is 610nm, the molar absorptivity is 9. 59×104L.mol-1. cm-1. Beer's law is obeyed over the range of 0￣50μg/25mL. This method is simple and rapid. Better selectivity is obtained, the tolerance limits of common ions are large and 8-fold of Ta to Nb has no interference. When applied to the determination of microamount of Nb(V) in mineral sample, satisfactory result was obtained.