江西名茶中Cr、Ni和Co3种重金属元素含量的比较分析

Comparative Analysis of the Contents of Three Heavy Metal Elements Cr,Ni,Co in Jiangxi Famous Teas

【目的】建立Cr、Ni和Co 3种重金属元素含量测定的石墨炉原子吸收光谱法,并利用建立的方法测定8种江西名茶中相应的3种重金属元素的含量,同时进行比较分析。【方法】首先通过正交试验设计优选各元素测定的仪器最佳工作条件,在最佳仪器工作条件下建立各元素的标准曲线,同时考察建立方法的检出限、精密度;然后优化前处理条件,在优选的前处理条件下,测定样品加标回收率,考察建立方法的准确度;最后利用建立的方法测定8种江西名茶中3种元素的含量并对其进行比较分析。【结果】建立的各元素原子吸收光谱法在相应浓度区间内线性关系良好,相关系数为0.9946~0.9993,精密度RSD值为3.93%~8.06%,检出限为0.88~5.625μg/mL,回收率为70.02%~93.50%,均符合要求。3种元素测定结果表明各元素在8种茶叶中的含量存在一定的差异显著性,各元素含量在不同茶叶中的由大到小排序基本为Ni、Cr和Co,Ni元素含量最高的是婺源毛尖;Cr元素含量最高的是庐山云雾;Co元素含量最高的是井冈翠绿。【结论】建立的茶叶中3种重金属元素含量的石墨炉原子吸收光谱法操作简便,干扰较少,灵敏度高,对其他各种茶叶中相应元素含量的测定均适用,测得的8种江西名茶中Cr、Ni和Co 3种重金属元素含量均较低,符合食用要求。

[Objective]A graphite furnace atomic absorption spectrometry was established to determine the contents of three heavy elements in eight Jiangxi famous teas for comparison and analysis.[Method]Firstly,the optimal working conditions for the instruments determining each element were optimized by orthogonal test design,and the standard curve of each element was established under the optimal instrument working conditions.At the same time,the detection limit and precision of the established method were examined.Then the pretreatment conditions were optimized.Under the optimal pre-treatment conditions,the spiked recovery of the sample was determined and the accuracy of the established method was examined.Finally,the established method was used to determine the contents of the three elements in eight Jiangxi famous teas,which were compared and analyzed.[Result]The results show that the established atomic absorption spectrometry had a good linear relationship in the corresponding concentration range.The correlation coefficient was 0.9946-0.9993,the precision RSD value was 3.93%-8.06%,the detection limit was 0.88-5.625μg/mL,and the recovery rate was 70.02%-93.50%,which all met the requirements.The determination results of the three elements showed that the contents of each element in the eight kinds of tea were significantly different.The order of each element content in different teas was basically Ni>Cr>Co,the highest Ni content was in Wuyuan Maojian;the highest Cr content was in Lushan Yunwu;the highest Co content was in Jinggang Cuilu.[Conclusion]The graphite furnace atomic absorption spectrometry with the contents of three heavy elements in tea set up in this paper is simple and easy to operate with less interference but high sensitivity.It is applicable to the determination of corresponding elements in various other teas.The contents of Cr,Ni,and Co in the eight Jiangxi famous teas are all relatively low,which meets the requirements for consumption.