Chemical Composition Analysis of Eucalyptus citriodora Essential Oil Using GC-MS and NMR Spectroscopy

Background and Objective: The simultaneous utilization of GC-MS and NMR offers valuable and complementary insights into the molecular weight and chemical structure of compounds, respectively. This research aimed to employ GC-MS and NMR spectroscopy to analyze the essential oil extracted from dried leaves of Eucalyptus citriodora sourced from Kaduna, Nigeria. Materials and Methods: The leaves were collected from various trees in a farm site in Kaduna metropolis, Kaduna state and processed into an extract. Hydrodistillation extraction (HDE) and GC-MS (HDE-GC-MS) techniques were employed to extract and analyze the volatile compounds, or VOCs, from Eucalyptus citriodora leaf, with each component's percentage reported as raw area percentage based on the total ion current. Results: The extraction method employed to obtain the essential oil was hydrodistillation, resulting in a yield of 3.5% (v/w). Examination of the oil composition identified twenty-nine distinct components, collectively constituting 100% of the volatile oils. Among these constituents, citronellal stood out as the primary monoterpene, with isopulegol, citronellol, 3-tetradecanol and citronellic acid following suit. Further validation through 2D NMR analysis conclusively identified citronellal as the principal component. Additionally, minor quantities of other compounds such as citronellyl acetate, p-methane-1,8-diol, cyclohexylacetone, 5-caranol, caryophyllene, caryophyllene oxide, β-pinene, eucalyptol, myrcenol, menthone, citronellol epoxide, linalool, citronellyl formate, α-pinene, methyleugenol, geraniol and geranyl acetate were identified. Conclusion: The analysis of the essential oil from E. citriodora using GC-MS and NMR techniques revealed a predominance of monoterpenes, with citronellal identified as the major constituent, constituting 46.87% of the total composition.