本文利用自然界中物質組成之同位素比會受原料、製程和環境影響而有所不同，以碳同位素比為例，植物依照光合作用途徑：碳三途徑、碳四途徑與景天酸代謝，分類成C3、C4、和CAM植物，合成出不同的碳同位素比醣類，發酵製得的酒精之碳同位素比也因此不同。本研究開發利用氣相層析同位素比質譜儀進行化合物別同位素分析，以鑑定酒類摻假的方法，應用到100種酒品之摻假鑑定。結果證實利用有機化合物之組成元素的同位素比特異性，得以區別相同分子組成之有機化合物，化合物別同位素分析法可以彌補目前以分子組成為分析基礎之氣相層析質譜法之不足。

This research exploits that the isotopic ratio of natural materials is different dictated by their effects by feed, process, and environment. Plants are classified into C3, C4, and CAM plant depending on their photosynthetic pathway. Plant sugars thus possessing different carbon isotopic ratio. Alcohols fragmented from sugars also possess different carbon isotopic ratio. Based on this principle, we have developed a compound specific isotope analysis (CSIA) method using gas chromatograph-isotope ratio mass spectrometer (GC-IRMS) for forensic identification of adulterated wines and applied to 100 brands of wine. Our results demonstrate that by exploiting the unique isotopic property of composing elements it is possible to differentiate organic compounds with similar molecular composition. The CSIA method could compensate the deficiency of molecular-composition base gas chromatograph mass spectrometry.