针对目前市场上存在的产地假冒茶叶严重影响名牌茶叶信誉的情况,根据不同产地茶叶中重金属含量的差异,提出了利用X射线荧光技术结合模式识别技术进行了茶叶产地鉴别的方法。将不同产地的样本分组,分别采集其X射线荧光光谱,提取其主成分,分别计算各个样本组的主成分均值作为样本中心点,计算待测样本到各样本组中心的马氏距离,将其归类到马氏距离值最小的类中,实现样本分类。采用Niton 792便携式X射线荧光仪对安吉、 金华、杭州和台州等4个不同地区120个茶叶样本进行了鉴别试验,发现3-13keV波段是X射线荧光光谱分析技术进行茶叶产地鉴别的有效波段,前4个主成分可用于茶叶的产地鉴别,试验的误差率为4.2%。

The existence of fake tea from non-origin seriously impacts on the credibility of the famous tea.A method was developed to identify tea from difference regions on the basis of the fact that the content of heavy metals in different origin tea is varied by using X-ray fluorescence technique and pattern recognition technique.Samples from different origins were grouped respectively,and their X-ray fluorescence spectra were acquired,and then the principal components of these spectral data were calculated,and the average of the principal components of each group was used as the center of each group.The Mahalanobis distance value between a sample and the center of a group were calculated,when the Mahalanobis distance value reached minimum,the sample was classed to current group,and in this way,a sample was identified.A Niton 792 portable X-ray spectrometer was used to class 120 tea samples from Anji,Jinhua,Hangzhou and Taizhou,in zhejiang province of China.It was found that the spectra between 3 and 13 KeV and the first 4 principal components give enough information for the identification of tea from different regions,and the rate of error was 4.2%.