基于稀土元素指纹分析判别安溪铁观音和华安铁观音的研究

Application of Heavy Rare Earth Elements as a Fingerprint in Discriminant Analysis of An'xi Tieguanyin Tea and Hua'an Tieguanyin Tea

安溪县和华安县是地缘相邻的两大福建省铁观音产地。安溪铁观音和华安铁观音各有特色,但不易区分及溯源。本研究为探讨基于稀土元素指纹对安溪铁观音和华安铁观音判别的有效性,找寻具表征判别特定的稀土元素指标,采用电感耦合等离子体发射光谱法(ICP-MS)测定安溪县、华安县铁观音样品中的16种稀土元素(钪Sc、钇Y、镧La、铈Ce、镨Pr、钕Nd、钐Sm、铕Eu、钆Gd、铽Tb、镝Dy、钬Ho、铒Er、铥Tm、镱Yb和镥Lu)含量,对数据进行独立样本t检验、主成分分析和Wilk’sλ判别分析,筛选出4个有效判别指标稀土元素Y、Pr、Gd、Dy,建立安溪铁观音和华安铁观音的判别模型,Y_(安溪铁观音)=37.363 Y+1.721 Pr-84.449Gd+47.502 Dy-3.187、Y_(华安铁观音)=61.613 Y+3.684 Pr-195.506 Gd+267.901 Dy-9.938,产地检验判别率为92.2%,交叉检验判别率92.2%。可见,稀土元素指纹技术用于判定安溪铁观音和华安铁观音具有较强的可行性。

An’xi county and Hua’an county are two adjacent major producing areas of Tieguanyin tea in Fujian province. An’xi Tieguanyin tea and Hua’an Tieguanyin tea have their own characteristics, and it is difficult to distinguish between them and trace the producing area. In order to examine the feasibility of using rare earth elements as a fingerprint to distinguish An’xi Tieguanyin tea and Hua’an Tieguanyin tea, the contents of 16 rare earth elements（scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium） of two types of Tieguanyin tea samples were determined by inductively coupled plasma mass spectrometry（ICP-MS）. The independent sample t test, principal component analysis and Wilk’s λ discriminant analysis were performed on the collected data, four variables（yttrium, praseodymium, gadolinium, and dysprosium） for effective identification were screened out, and discriminant models for An’xi Tieguanyin tea and Hua’an Tieguanyin tea were established： Y（Anxi）=37.363 Y＋1.721 Pr-84.449 Gd＋47.502 Dy-3.187, Y（Hua’an）=61.613 Y ＋ 3.684 Pr-195.506 Gd＋267.901 Dy-9.938, in which the differentiation rates for producing area validation and cross validation were both 92.2%. Therefore, it is feasible to distinguish An’xi Tieguanyin tea from Hua’an Tieguanyin tea by using heavy rare-earth elements as a fingerprint.