光度法快速测定铜合金中微量铝

RAPID DETERMINATION OF TRACE ALUMINUM IN COPPER ALLOYS

在pH 4～6的六次甲基四胺介质中,显色剂偶氮氯膦Ⅰ与铝形成稳定的蓝紫色络合物。讨论了吸收光谱、酸度、试剂用量、干扰离子等因素对实验的影响,确定了反应的最佳条件。铝含量在0～25μg/(50 mL)范围内符合比耳定律,铝络合物在600 nm处有最大吸收,表观摩尔吸光系数为3.9×104L/(mol.cm)。用EDTA-Mn作掩蔽剂,共存元素均不干扰测定,方法有良好的选择性。此法可不经过分离直接测定铜合金中的微量铝,测定结果的相对标准偏差小于2%(n=5),测定结果与认定值相符。

In hexamethylenetetramine medium pH 4 - 6, aluminum reacts with chlorophosphonazo I to form a blue - violet complex which exhibits an absorption maximum at 600 nm with a apparent molar absorptivity of 3.9 x 104 L/（ mol · cm）. The absorp- tion spectra, acidity, reagent dosage, interfering ions and other factors were discussed, and the experimental conditions were opti- mized. Beer＇s law was obeyed in the range of 0 -25 p,g/（50 mL） for aluminum with EDTA -Mn as a masking agent. Coexisting ele-ments didn＇t interfere with the determination, the method had good selectivity. The proposed method can be applied to determine alu- minum directly in copper alloy, and the RSD was less than 2% （ n = 5 ）. The determination results were corresponded with the certified values.