Cu2+-钨酸盐-罗丹明6G体系共振散射光谱法测定面粉和茶叶中微量铜

Determination of Copper in Flour and Tea by Resonance Light-Scattering Technique with Cu^(2+)-Tungstate-Rhodamine 6G System

利用Cu2+和钨酸盐形成的铜钨杂多酸阴离子与罗丹明6G阳离子结合生成离子缔合物的反应,建立一种测定Cu2+的共振散射光谱法。该反应在聚乙烯醇存在条件下,于589 nm波长处产生的共振散射光强度与Cu2+质量浓度在0.05~1.0 ng/m L范围内有良好的线性关系,线性回归方程为ΔI=4.38+77.12c(r=0.997 1),方法的仪器检出限为0.026 ng/m L。方法简单、快速、灵敏度高,且大量存在的常见离子对Cu2+的测定不干扰,将其用于面粉和茶叶样品中铜的测定,相对标准偏差在3.5%以内,回收率在96.7%~104.1%之间。

Objective: To develop a method for the determination of copper in food samples. Methods: Resonance lightscattering technique was used. Results: The resonance light-scattering signal at 589 nm was observed when a ion-associated complex was formed among Cu2+, tungstate and rhodamine 6G in the presence of polyvinyl alcohol(PVA). The lightscattering intensity increased linearly with increasing concentration of Cu2+ in the range of 0.05–1.0 ng/m L. The linear regression equation was ΔI = 4.38 + 77.12c(r = 0.997 1), and the detection limit was 0.026 ng/m L. The relative standard deviations and recovery rates of the proposed method for the determination of copper in flour and tea were less than 3.5%and in the range of 96.7%–104.1%, respectively, suggesting that this method was free from the interference of significant amounts of other common ions. Conclusion: The proposed method possesses the advantages of simple operation, rapid determination, excellent reproducibility, high sensitivity and good selectivity so that it can be used for the determination of copper in food samples.