【摘要】 DBC-偶氮氯膦在中性或酸性水溶液中呈现紫红色,以水为参比,λ_max550nm。在硫酸介质中与Bl³⁺形成蓝紫色络合物,λ_max642nm,对比度△λ92nm。显色剂以在高氯酸、硫酸介质中的灵敏度最好。在硫酸溶液中加少量乙醇,灵敏度提高25％,e=1.06×10⁵l·mol^-1·cm^-1。硫酸介质中的酸度范围为5×10^-3M～0.6M,络合比Bi³⁺:DBC=1:2。实验了阴、阳离子25种,大多数的允许量为毫克级,其中稀土、Zr（Ⅳ）,Th（Ⅳ）干扰测定。Bi³⁺的量在0～15μg/25 ml符合比尔定律。用此方法分析了铅基合金、白钨矿中的微量铋,加酒石酸掩蔽Fe³⁺、Sb³⁺,加苦杏仁酸掩蔽Ti⁴⁺、Sn²⁺,进一步提高了方法的选择性。标准偏差1.72×10^-4～1.2×10^-2％。更多还原

【Abstract】 DBC-chlorophosphonazo [2-（4-chloro-2-phosphonophenylazo）-7-（2,6-dibromo-4-chlorophenylazo）-1, 8-dihydroxy-3,6-naphthalencdisulfonic acid] is a new color reagent for the determination of Bi³⁺ in sulfuric acid (5×10^-3～0.6M) medium The molar absorptivity is 1.06×10⁵l·mol^-1·cm^-1 for Bi³⁺-complex at 642nm.The composition of the complex is Bi³⁺:DBC=1:2.The apparent stability constant of the complex has been calculated to be 7.25×10⁸. Beer’s law is obeyed in the range of 0～15μg Bi³⁺ per 25mlThe method has been applied to the determination of trace Bi³⁺ in plumbum alloys and minerals of white-wolfram ore.更多还原