Abstract:

Based on the colour reaction of cadmium(Ⅱ)with 2-[(5-bromo-2-pyridyl)-azo]-5-diethylaminophenol(5-Br-PADAP)in the medium of borax-boric acid buffer solution(pH 8.5)containing surfactant triton X-100,the highly sensitive spectrophotometric method for determining trace cadmium(Ⅱ)has been proposed.The complex has a maximum absorption wavelength at 560 nm.The molar ratio of cadmium(Ⅱ)to 5-Br-PADAP in the complex is 1:2.The apparent molar absorptivity is 3.23 × 10⁵ L/(mol·cm).The Beer's law is obeyed in the concentration range of 0-320 μg/L for cadmium.Interference from other metal ions can be eliminated by sulfhydryl cotton.The advantages of this possess are high sensitivity,fine repeatability,color stabilization and wide range of coloring temperature,and it is applied to the determination of trace cadmium in water with satisfaction.

Key words: cadmium, spectrophotometry, 2-〔(5-bromo-2-pyridyl)-azo〕-5-diethylaminophenol

摘要：

研究了在pH8.5的硼砂-硼酸缓冲溶液中,在表面活性剂辛基酚聚氧乙烯醚(曲拉通X-100)存在下,Cd(Ⅱ)与2-[5-溴-2-吡啶偶氮]-5-二乙氨基苯酚(5-Br-PADAP)形成有色络合物的条件。络合物的最大吸收波长为560nm,其络合比为nCd(Ⅱ)〕:n(5-Br-PADAP)=1︰2,表观摩尔吸光系数为3.23×10⁵L/(mol.cm)。镉质量浓度在0～320μg/L符合比尔定律。通过巯基棉柱富集、分离,除去大量的干扰离子。该方法灵敏度高,有色络合物稳定时间长,显色温度范围宽,重现性好,应用于水中微量镉的测定,结果满意。

关键词: 镉, 分光光度法, 2-〔5-溴-2-吡啶偶氮〕-5-二乙氨基苯酚

CLC Number: 

• O657.32