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应用Al-CAS-OP三元胶束测定钢中铝,文献[1, 2]有不少报道,一般用六次甲基四胺或乙酸盐缓冲剂控制pH,然后显色。由于三元胶束的形成酸度在 pH6.2左右,而上述缓冲剂的缓冲范围在pH 4～6之间,两者不同步,因此,原方法的缺点是酸度不易掌握, 重现性欠佳。我们在研究Al-CAS-OP-CPB四元体系时,发现乙二胺-盐酸缓冲溶液性能良好。它的第二个缓冲范围在 PH 5.8～7.8之间,与胶束的形成酸度一致。试验发现, 乙二胺不仅能掩蔽大量的镍、钴、铜,而且能改善胶束的形成条件,扩大OP的用量范围。本文利用这种缓冲剂,研究了Al-CAS-OP的配合比,拟定了直接测定低合金钢和部分铬镍钢中铝的方法,用于样品分析,结果满意。 1 试验部分 1.1 试剂与仪器 721 型分光光度计 25 型酸度计铝标准溶液:Al 100μg·ml~(-1),称取纯铝0.1000g 置于聚四氟乙烯塑料杯中,加入氢氧化钠溶液(10%) 20ml,加热溶解后,加入盐酸(1+1)30ml,冷却至室温, 转移到1L量瓶中,以水稀至刻度摇匀。用时稀释50倍
Al-CAS-OP ternary micelles for the determination of aluminum in steel has been reported in literatures [1, 2]. The pH is usually controlled with hexamethylenetetramine or acetate buffer and then developed. Due to the formation of ternary micelles acidity at pH6.2, while the buffer buffer in the pH range of 4 to 6, the two are not synchronized, therefore, the original method is not easy to grasp the acidity, poor reproducibility . We studied the Al-CAS-OP-CPB quaternary system and found that ethylenediamine - hydrochloric acid buffer solution performance is good. Its second buffer range is between pH 5.8 and 7.8, consistent with the formation of micellar acidity. It was found that ethylenediamine can not only mask a large amount of nickel, cobalt and copper, but also improve micelle formation conditions and increase the dosage range of OP. In this paper, we studied the blending ratio of Al-CAS-OP and prepared a direct method for the determination of aluminum in low-alloy steel and some chromium-nickel steel with this buffer. The method was used for sample analysis with satisfactory results. 1 Experimental 1.1 Reagents and Instruments 721 spectrophotometer 25 type acid meter aluminum standard solution: Al 100μg · ml -1, weighed pure aluminum 0.1000g placed in a Teflon plastic cup, add sodium hydroxide Solution (10%) 20ml, heated to dissolve, add hydrochloric acid (1 +1) 30ml, cooled to room temperature, transferred to a 1L volumetric flask, diluted with water to the mark. When diluted with 50 times