X射线荧光光谱法测定花草茶中22种元素

采用粉末压片法制样，应用X射线荧光光谱法对花草茶中N，Na，Mg，Al，Si，P，S，Cl，K，Ca，Ti，Cr，Mn，Fe，Ni，Cu，Zn，Br，Rb，Sr，Ba，Pb共22种元素进行了分析。讨论了测量条件的选择，对于22种目标元素的分析线，除Ba，Pb采用L线外，其余都选择K_α线，在对Rh靶K_α线的康普顿散射进行测量时，应适当降低管电压，选择合适的管电流。采用经验系数法和3条散射谱线(Rh靶L_α线的瑞利散射、0.1876nm处的散射线、Rh靶K_α线的康普顿散射)作内标进行基体效应校正，并对N，Na，Ca，Ti，Mn，Sr，Ba等部分元素进行了谱线重叠干扰校正。实验结果表明，该方法对N，Na，Mg，Al，Si，P，S，Cl，K，Ca，Ti，Cr，Mn，Fe，Ni，Cu，Zn，Br，Rb，Sr，Ba，Pb各目标元素的检出限较低，且准确度较好，精密度较高。采用该方法对花草茶中元素的种类和含量信息进行分析发现，花草茶元素组成较为丰富，不同种类花草茶元素种类和含量有差异，且同一种类不同来源花草茶略有差异，但元素组成含量特征大体相似。综上可知，该方法操作简单，能够实现花草茶的低成本、快速、准确、多元素测定。

Determination of 22 Elements in Herb Tea by X-Ray Fluorescence Spectrometry

N，Na，Mg，Al，Si，P，S，Cl，K，Ca，Ti，Cr，Mn，Fe，Ni，Cu，Zn，Br，Rb，Sr，Ba and Pb in herb tea were determined by X-ray fluorescence spectrometry with pressed powder pellets. The measuring conditions of target elements were investigated, including how to select its analytical line. In addition to Ba and Pb using L line, K_α line was selected for the rest. When the Compton scattered radiation of Rh K_α was measured, The X-ray tube voltage should be appropriately reduced, and the appropriate tube current should be selected. The matrix effect was corrected by empirical coefficient method and using scattered radiation (the Rayleigh scattered radiation of Rh L_α, the scattered background of 0.187 6 nm wavelength position and the Compton scattered radiation of Rh K_α) as internal standard, and the spectral overlapping interference of some elements (N, Na, Ca, Ti, Mn, Sr and Ba) was corrected. For the target elements, the detection limit of this method was low, and its accuracy and precision were high. The results showed that there were abandon of elements in herb tea, of which different kinds had different components, even the same kind of herb tea with different source had some difference in element and content more or less, however, there was a lot of similarity between the features of its components. In a word, this method could achieve multi-element determination of herb tea, and it was simple in operation, low cost, rapid, and accurate.