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目的:建立用电感耦合等离子体原子发射光谱法(ICP-AES)测定食品包装铝材中Cu、Ni和Zn含量的分析方法。方法:在试液中加入少量EDTA使其浓度为0.010 0 mol·L~(-1),调节溶液pH=5.0,用强酸性阳离子交换纤维对Al~(3+)进行超声辅助萃取,由于Al~(3+)不能与EDTA迅速形成配阴离子,则被强酸性阳离子交换纤维吸附,而Cu~(2+)、Ni~(2+)和Zn~(2+)能与EDTA迅速形成不被强酸性阳离子交换纤维吸附的配阴离子,则留在溶液中待测定。结果:试液经过分离后,Cu、Ni和Zn未见损失,而残留Al的质量浓度约是Cu、Ni、Zn的170倍,不干扰ICP-AES的测定。样品标准加入的回收率均在95.3%~104%之间,RSD在0.2%~2.5%(n=5)之间;标准物质中Ni、Cu和Zn的测定值对认定值的相对误差均小于5.0%。结论:本方法可用于铝制饮料易拉罐、烘烤食品用铝箔和标准物质等样品中Ni、Cu和Zn的测定。
Objective: To establish an analytical method for the determination of Cu, Ni and Zn in food packaging aluminum by inductively coupled plasma atomic emission spectrometry (ICP-AES). Methods: A small amount of EDTA was added to the test solution to make the concentration of 0.010 0 mol·L -1. The pH value of the solution was adjusted to 5.0. Ultrasonic-assisted extraction of Al 3+ with strongly acidic cation exchange fiber was carried out. Since Al ~ (3 +) could not form anion with EDTA quickly, then it was adsorbed by strongly acidic cation exchange fiber, but Cu 2+, Ni 2+ and Zn 2+ could form rapidly with EDTA Strong acid cation exchange fiber adsorption with anions, then remain in solution to be determined. Results: After the test solution was separated, no loss was found in Cu, Ni and Zn, while the residual Al concentration was about 170 times that of Cu, Ni, Zn and did not interfere with ICP-AES determination. The recoveries of standard samples were all between 95.3% and 104% with RSDs between 0.2% and 2.5% (n = 5). The relative errors of the values of Ni, Cu and Zn in the reference materials were all less than 5.0%. Conclusion: This method can be used for the determination of Ni, Cu and Zn in aluminum beverage cans, aluminum foil for bakery products and standard samples.