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合成了新显色剂2-羧基-4′-硝基苯基重氮氨基偶氮苯(CNADAA),并研究了其在Triton X-100存在下与镉(Ⅱ)的显色反应。结果表明,在pH 10.75的NaB4O7-NaOH缓冲介质中,该试剂与镉(Ⅱ)形成摩尔比为1∶1的红色配合物,最大吸收波长580 nm,表观摩尔吸光系数ε=1.32×105L.mol-1.cm-1。镉(Ⅱ)的质量浓度在0~0.8μg/mL范围内遵守比耳定律。所拟方法用于废水中微量镉(Ⅱ)的测定,相对标准偏差为1.8%~2.9%,回收率为97.6%~103.2%。
A new chromogenic reagent 2-carboxy-4’-nitrophenyldiazoaminoazobenzene (CNADAA) was synthesized and its color reaction with cadmium (Ⅱ) was studied in the presence of Triton X-100. The results showed that the complex formed a red complex with cadmium at a molar ratio of 1: 1 at pH 10.75 in NaB 4 O 7-NaOH buffer solution. The maximum absorption wavelength was 580 nm and the apparent molar absorptivity ε = 1.32 × 105 L. mol-1.cm-1. Beer’s law is obeyed in the range of 0 ~ 0.8 μg / mL for cadmium (Ⅱ). The proposed method was applied to the determination of trace cadmium (Ⅱ) in wastewater with the relative standard deviations of 1.8% -2.9% and the recoveries of 97.6% -103.2%.