Triton X-100 存在下偶氮氯膦Ⅲ分光光度法测定锰化合物中的微量钙

Spectrophotometric Determination of Trace Calcium(Ⅱ) with Chlorophosphonazo Ⅲ in Manganese Compound in the Presence of Triton X 100

研究了钙与偶氮氯膦Ⅲ（ＣＰＡⅢ）的配位显色反应。在非离子型表面活性剂ＴｒｉｔｏｎＸ－１００存在下，于ｐＨ２．５的邻苯二甲酸氢钾－盐酸缓冲溶液中，钙可与ＣＰＡⅢ形成１∶２稳定的蓝色配合物，其最大吸收波长为６５６ｎｍ，表观摩尔吸光系数为２．８４×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，钙量在０～３０μｇ／２５ｍＬ范围内服从比尔定律。本法已用于锰化合物中微量钙的测定。

The color reaction of calcium with chlorophosphonazoⅢ(CPAⅢ) system has been studied.In the presence of nonionic surfactant Triton X 100 and in C 8H 5O 4K HCl buffer solution at pH2.5,Ca reacts with CPAⅢ to form a stable blue complex with composition ratio of Ca(Ⅱ)/CPAⅢ of 1∶2 .The absorption maximum of the complex is at 656nm and its apparent molar absorptivity is 2 84×10 4 L·mol -1 ·cm -1 .Beer's law is obeyed in the range of 0～30μg/25mL for Ca.The method has been applied to the direct determination of Ca in manganese compound and tap water with satisfactory results.