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铜合金中微量镁的光度法测定,以二甲苯胺蓝、铬变酸2R或偶氮氯膦Ⅰ为显色剂时均需用铜试剂分离除去Cu~(2+)、Sn~(4+)、Zn~(2+)、Ni~(2+)、Fe~(3+)、Al~(3+)、Mn~(2+)、Sb~(3+)、Bi~(3+)等干扰离子,因而费时。本文在前人工作的基础上试验了不分离干扰离子的直接光度法的条件。表明:采用三乙醇胺-丙酮氰醇-EGTA-铅联合掩蔽干扰离子,在pH9.7—10.2的条件下,用偶氮氯膦Ⅰ作显色剂,可获得满意的结果。络合物的最大吸收波长为580nm,而试剂空白的吸收较小,表观摩尔吸光系数1.75×10~4,镁量小于30微克/50毫升符合比尔定律。共存元素允许量(毫克)为:Cu~(2+)(20),Zn~(2+)
Copper (Ⅱ), Sn ~ (4 +), Cu (Ⅱ), Cu (Ⅱ) Zn 2+, Ni 2+, Fe 3+, Al 3+, Mn 2+, Sb 3+, Bi 3+, Zn 2+, Interfering ions, so time-consuming. Based on the previous work, this paper tests the conditions of the direct photometric method without separation of interfering ions. The results show that the combination of triethanolamine - acetone cyanohydrin - EGTA - lead masking interference ions and the use of chlorophosphonazo I as chromogenic reagent at pH9.7-10.2 can give satisfactory results. The maximum absorption wavelength of the complex is 580nm, while the reagent blank absorption is small, the apparent molar absorption coefficient of 1.75 × 10 ~ 4, the amount of less than 30 micrograms of magnesium / 50 ml Beer’s Law. Coexistence of elements allowable amount (mg): Cu ~ (2 +) (20), Zn ~ (2+)