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目的:研究二甲酚橙与铝的显色反应体系,建立分光光度法测定硼砂中微量铝的新方法。方法:在表面活性剂吐温-20存在下,pH 3.0的醋酸-醋酸钠缓冲液介质中,铝与二甲酚橙以1∶1形成稳定的紫红色络合物,在550 nm处测定其吸光度,并计算铝的含量。结果:铝离子质量浓度在0.3～0.13 mg.L-1与吸光度呈良好的线性关系(r=0.998 4);重复性试验RSD为0.83%;加标回收率为98.83%,RSD为2.31%;最低检出量0.032 mg.L-1。结论:该方法简便、快速、显色稳定,适用于硼砂中的微量铝的测定。
Objective: To study the chromogenic reaction system of xylenol orange and aluminum and to establish a new spectrophotometric method for the determination of trace aluminum in borax. METHODS: In the presence of surfactant Tween-20, a stable fuchsine complex was formed at 1: 1 between aluminum and xylenol orange in acetate-sodium acetate buffer at pH 3.0 and was measured at 550 nm Absorbance, and calculate the aluminum content. Results: The linearity of the concentration of aluminum ion was 0.3-0.13 mg · L -1 and the absorbance was linear (r = 0.998 4). The RSD of repeatability test was 0.83%. The recoveries were 98.83% and RSD was 2.31% The minimum detectable amount is 0.032 mg.L-1. Conclusion: The method is simple, rapid and stable in color. It is suitable for the determination of trace aluminum in borax.