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2—(5—溴—2—吡啶偶氮)—5—二乙氨基苯酚(简称5—Br—PADAP)是吸光光度法测定微量金属离子的灵敏显色剂,但用于阴离子的测定报导较少.本文研究了5—Br—PADAP 在酸性介质中质子化,与 IO_3~-和 SCN~-生成紫红色的三元离子缔合物,其最大吸收波长λ_(max)=540nm.利用这一缔合反应建立了测定微量 SCN~-离子的吸光光度分析法,其摩尔吸光系数ε_(540)~(SCN~-)=1.05×10~5L·mol~(-1)·Cm~(-1).应用于化纤厂工业废水中 SCN~-离子的测定,结果满意,回收率在96～102%之间.
2- (5-bromo-2-pyridylazo) -5-diethylaminophenol (referred to as 5-Br-PADAP) is a sensitive chromogenic reagent for the determination of trace metal ions by spectrophotometry, Less.This paper studied the protonation of 5-Br-PADAP in acid medium and the formation of magenta ternary ion association with IO_3 ~ - and SCN ~ -, the maximum absorption wavelength λ max = 540nm.Using this (SCN ~ -) = 1.05 × 10 ~ 5L · mol ~ (-1) · cm ~ (-1) · cm ~ (-1) · cm ~ ) Is applied to the determination of SCN ~ - in industrial wastewater from chemical fiber factories, with satisfactory results and the recovery rate is between 96% and 102%.