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偶氮氯瞵Ⅲ(CPAⅢ)是稀土元素的良好显色剂已为人们所共知,但用作铅(Ⅱ)的显色剂,目前尚未见报导。作者对此显色反应条件进行了—些初步探讨。表明,偶氮氯膦Ⅲ在pH1.8—2.2的溶液中与铅形成组成比Pb:CPAⅢ=1:1的蓝色络合物,其λ_(max)=615nm,ε_(615)=2.57×10~4,铅量在0—100微克/50毫升范围内服从比尔定律。络合物瞬时形成,至少可稳定1小时。在酒石酸存在下,允许较大量的锑(Ⅲ)共存。方法用于锑中铅的测定获得较为满意的结果,可测定0.05%以上的铅。一、仪器与主要试剂721型分光光度计;雷磁25型酸度计。CPAⅢ溶液(0.1%)配制后静置一昼夜,过滤。氯乙酸-乙酸钠缓冲液(pH=2)2M氯乙酸溶液用2M乙酸钠溶液在pH计上调至pH=2。
It has been well known that CPAⅢ is a good chromogenic reagent of rare earth elements. However, it has not been reported yet that it is used as a chromogen of lead (Ⅱ). The authors carried out the color reaction conditions - some preliminary discussion. It is shown that the blue complex of chlorophosphonazo Ⅲ with Pb in the solution of pH1.8-2.2 forms a blue complex with Pb: CPAIII = 1: 1, λ max = 615 nm and ε 615 = 2.57 × 10 ~ 4, the amount of lead in the range of 0-100 micrograms / 50 ml obey Bill’s law. Complex formation instantaneous, stable for at least 1 hour. In the presence of tartaric acid, a larger amount of antimony (III) is allowed to coexist. Method for the determination of lead in antimony obtained more satisfactory results, can be determined more than 0.05% of lead. First, the instrument and the main reagent 721 spectrophotometer; Leica 25 acidity meter. CPA Ⅲ solution (0.1%) formulated for a day and night, filtered. Chloroacetic acid-sodium acetate buffer (pH = 2) 2M chloroacetic acid solution was adjusted to pH = 2 with 2 M sodium acetate solution in a pH meter.