基于EDXRF技术茶叶中金属元素检测方法研究

能量色散X射线荧光光谱(EDXRF)法作为化学元素分析的一种检测手段，被广泛应用于地质勘测、工矿石油、生化医疗及刑侦考古等各行各业，它是户外现场检测与分析的首选方法之一。利用EDXRF法检测茶叶中金属元素含量，对环境条件要求低，且无需对茶叶样品进行化学处理。实验检测发现，用该方法分析茶叶中金属元素时，有效X射线荧光光子能量段在3～16 keV之间，故校正光谱元素选择位于能量中心位置(8 keV)附近的铜元素，并用铜元素定标做标准曲线，在茶叶有效X射线荧光光子能量段中，通过样品加标方法分析铜、铁、锌、铅四种元素，求得平均检出限为1.25 mg·kg-1。在检测茶叶中金属元素的化学方法中，选用火焰原子吸收法测得茶叶中金属元素含量作为标准值，比较得出，EDXRF法测得数值实际相对误差小于6%，相对标准偏差小于5%，经过t检验，p＞0.05，说明EDXRF法与火焰原子吸收法在统计学上没有显著差异，两种方法所测结果吻合。结果表明，EDXRF法检测茶叶中金属含量的方法是可行的，结果满足现场检测分析需求。

Research on Test Method of Metallic Element Contained in Tea Based on EDXRF Technique

As it has been certified by experimental testing that when using the energy-dispersive X-ray fluorescence (EDXRF) method to analyze the metallic elements contained in the tea the energy segment of effective X-ray fluorescence photons is located between 3 and 16 keV. Accordingly the spectral correction element is targeted at the copper elements located near the energy center(8 keV). The copper elements are also used as the picketage to be the standard curve. In the energy segment of effective X-ray fluorescence photons contained in the tea 1.25 mg·kg-1 of the average detection limit was obtained by using the spiked method to analyze four elements of copper, iron, zinc and lead. Compared with the flame atomic absorption spectrum(FAAS), the actual relative error of the tested value by EDXRF is less than 6%, and the relative standard deviation is less than 5%. The result by T test shows that p>0.05. The conclusions are that there are no statistically significant differences between EDXRF and FAAS. The measured results gained by the two methods agree with each other. And EDXRF can be used thoroughly to test the metal contents contained in the tea. The result shows that it is feasible to test the metallic contents contained in the tea by EDXRF, and its measured result can meet the requirements of field testing and analysis.