Extraction and Characterisation of Essential Oils from Cymbopogon citratus Cultivated in Oyo State, South West Nigeria

Cymbopogon citratus, commonly known as lemongrass, is cultivated across the humid zones of South West Nigeria for culinary, medicinal, and cosmetic applications, and its essential oil is increasingly valued globally for antimicrobial and aromatic properties. This study extracts and characterises the essential oil of lemongrass grown at two cultivation sites in Oyo State, South West Nigeria, using hydrodistillation in a Clevenger apparatus. Oil yield is determined gravimetrically. Chemical composition analysis is performed by gas chromatography coupled with mass spectrometry, with compound identification by comparison against the National Institute of Standards and Technology spectral library. Physical properties measured include density, refractive index, optical rotation, and solubility parameters. The dominant constituents, particularly citral isomers (geranial and neral) as markers of quality, are quantified relative to total oil composition. The study also compares oil yields and compositional profiles between samples harvested at different growth stages: three, six, and nine months post-planting. Antimicrobial potential of the extracted oil is screened against Staphylococcus aureus and Escherichia coli using the disc diffusion method. Results are expected to reveal citral concentrations exceeding sixty-five percent, meeting international quality thresholds for commercial lemongrass oil. Findings support valorisation of lemongrass cultivation in Oyo State and contribute to plant-based aromatherapy and cosmetic product development. Keywords: lemongrass, essential oil, Cymbopogon citratus, gas chromatography-mass spectrometry, Oyo State