Identifying the geographical origin of tea has become imperative due to increased consumer awareness and turbulence in the tea market. In this study, the potential of stable isotope tracer technique and gas chromatography-ion mobility spectrometry (GC-IMS) for the differentiation of Tieguanyin (TGY) and Dahongpao (DHP) oolong tea, as well as DHP samples from three smaller parcels, was explored and compared. Both the methods are based on stable isotope signatures and GC–IMS clearly differentiated the TGY and DHP oolong tea, then the k-NN model was cross validated with an accuracy of 95.2% and 97.8%, respectively. GC–IMS was sensitive enough to distinguish different DHP samples with an acceptable accuracy of 86.7%, whereas stable isotope signatures showed an ineffective separation. In addition, we identify putative markers specific for the different areas. Finally, we revealed a significant correlation between stable isotope ratio and volatile compounds, although the underlying mechanism is still unclear.

中文翻译：

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稳定同位素特征与气相色谱-离子迁移谱法测定福建乌龙茶样品的地理起源

由于消费者对茶市场的意识增强和动荡，确定茶的地理起源已成为当务之急。在这项研究中，稳定同位素示踪技术和气相色谱-离子迁移谱法（GC-IMS）可以区分铁观音（TGY）和大红袍（DHP）乌龙茶，以及来自三个较小包裹的DHP样品。探索和比较。两种方法均基于稳定的同位素特征，GC-IMS明确区分了TGY和DHP乌龙茶，然后k-NN模型经过交叉验证，准确度分别为95.2％和97.8％。GC–IMS足够灵敏，能够以86.7％的可接受精度区分不同的DHP样品，而稳定的同位素特征表明分离效果不佳。此外，我们确定了特定于不同区域的推定标记。最后，我们揭示了稳定同位素比率与挥发性化合物之间的显着相关性，尽管其潜在机理仍不清楚。