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本文报道在乳化剂OP存在下,Cr(III)与2-(5-溴-吡啶偶氮)-5-二乙胺基酚(5-Br-PADAP,R)和H_2O_2的新显色反应。在pH6.0的乙酸-乙酸钠缓冲液中,Cr(III)与5-Br-PADAP和H_2O_2形成紫蓝色混配合物并增溶于乳化剂OP。配合物的λ_(max) 610nm(logε 5.08)。Cr(III)—5-Br-PADAP—H_2O_2的配合比为1:1:1。推测其结构为[Cr(O_2)R]。计算得表观稳定常数为1.9×10~(16)。配合物对H_2SO_4,KF或EDTA均稳定,可直接用于低合金钢和废水中微量铬的测定。Cr(III)在0～20μg/50mL范围内符合Beer定律。
This paper reports the new color reaction of Cr (III) with 2- (5-Br-PADAP, R) and H 2 O 2 in the presence of emulsifier OP. Cr (III) forms a purple-blue mixture with 5-Br-PADAP and H_2O_2 in acetic acid-sodium acetate buffer at pH 6.0 and solubilizes in emulsifier OP. The λ max of the complex was 610 nm (logε 5.08). The ratio of Cr (III) -5-Br-PADAP-H 2 O 2 is 1: 1: 1. It is presumed that the structure is [Cr (O_2) R]. The calculated apparent stability constant is 1.9 × 10 ~ (16). The complex is stable to H_2SO_4, KF or EDTA, and can be used for the determination of trace chromium in low alloy steel and wastewater. Beer’s law was obeyed in the range of 0 ~ 20μg / 50mL for Cr (III).