8-羟基喹啉分光光度法测定铍铜中间合金中铝

为测定铍铜中间合金中铝的含量，使用硝酸溶解试样，用氨水调节至pH 6～7，使铁、铝以氢氧化物形式沉淀，过滤并洗涤使其与基体铜分离。采用盐酸溶解沉淀，在pH 5.0的乙酸-乙酸钠缓冲溶液中，铝与8-羟基喹啉形成络合物，采用三氯甲烷萃取，络合物最大吸收波长位于393 nm处，表观摩尔吸光系数为6.45×10³ L·mol^-1·cm^-1。在三氯甲烷显色溶液中，铝离子的质量浓度在0～4 000 μg/L范围内符合比尔定律。铁、铜等干扰元素于显色前使用铜试剂-三氯甲烷萃取分离除去。方法适用于铍铜中间合金中0.000 2%～0.5%铝的测定，结果与ICP-AES法测定结果相符合，样品加标回收率为98%～102%。

Determination of aluminum in beryllium-copper master alloy by 8-hydroxyquinoline spectrophotometry

The beryllium copper intermediate alloy sample was dissolved by nitric acid to determine the content of aluminum. The pH of solution was adjusted to 6-7 using ammonia water. The iron and aluminum were precipitated in form of hydroxide. After filtration and washing, they were separated from matrix copper. The precipitation was dissolved with hydrochloric acid. In HAc-NaAc buffer solution at pH 5.0, aluminum reacted with 8-hydroxyquinoline to form complex, which was extracted with chloroform. The maximum absorption wavelength of complex was at 393 nm, and the apparent molar absorptivity was 6.45×10³ L·mol^-1·cm^-1. In chloroform coloring solution, the Beers law was obeyed for aluminum ion with mass concentration of 0-4 000 μg/L. The interference ions such as iron and copper were removed by cupron-chloroform extraction before coloring. This method was applicable for the determination of 0.000 2 %-0.5 % aluminum in beryllium copper intermediate alloy. The results were consistent with those obtained by ICP-AES. The recoveries of standard addition were 98%-102%.