The Allergen Detective: An Undergraduate GC-FID/MS Laboratory Activity for Investigation of Volatile Ingredients in Essential Oil

Abstract This laboratory experiment introduces a natural volatile product analysis experiment for undergraduate students majoring in chemistry and pharmacy, helping students to gain a deeper understanding of chromatographic methods in natural-product analysis. It involves the use of gas chromatography–flame ionization detector (GC-FID) and GC-mass spectrometry (GC-MS) in the quantitative and qualitative analysis of allergenic components in a commercial formulated essential oil product (Feng You Jing). The experiment was divided into two parts, each lasting 4 class hours. In the first part, the GC-FID method was employed to qualitatively analyze five known inherent allergenic components in Feng You Jing (eucalyptol, camphor, menthol, methyl salicylate, and eugenol), based on the retention time. The component menthol was selected for quantitative analysis using the internal standard method; in the second part, the GC-MS method was used to qualitatively analyze the five inherent allergenic components through MS signals. Meanwhile, a potential prohibited allergenic component (6-methylcoumarin) was qualitatively identified. By comparing the performance characteristics of GC-FID and GC-MS in qualitative and quantitative analyses, students gained a deeper understanding of the complementarity between the two techniques, providing practical experience for subsequent professional learning and research practice.