Enantiomer analysis of linalool in commercial bergamot (Citrus bergamia Risso) essential oils

• Published in: Japan Journal of Aromatherapy Vol. 26; no. 1; pp. 42 - 49
• Main Authors: SAWAMURA, Masayoshi, NAGANO, Momota, ASANO, Kimito, ASHIZAWA, Honami, KITAOKA, Yuichi
• Format: Journal Article
• Language: Japanese
• Published: Aroma Environment Association of Japan 07.02.2025; 公益社団法人 日本アロマ環境協会
• Subjects: bergamot essential oil; enantiomer; GC-MS SIM; linalool; linalyl acetate; エナンチオマー; ベルガモット精油; リナロール; 酢酸リナリル
• ISSN: 1346-3748; 2189-5147
• DOI: 10.15035/aeaj.260105

The purity of commercial bergamot (Citrus bergamia Risso) essential oils was assessed by analyzing the enantiomers of linalool and linalyl acetate. The study included 34 cold-pressed oils and one steam-distilled oil obtained from peels. Additionally, laboratory-prepared samples comprised a cold-pressed oil and a hexane-extracted oil from bergamot fruit. The analysis also included three aged cold-pressed oils and a racemic reagent of linalool. The enantiomeric analysis was performed using gas chromatography-mass spectrometry with a chiral column in the selected-ion monitoring mode. The mass units were set at m/z 71.0, 93.0, 80.0 and 121.0 for linalool and linalyl acetate. Results demonstrated that the enantiomer excess % of (R)-(−)-linalool over (S)-(+)-linalool exceeded 98.0% in most commercial cold-pressed and steam-distilled bergamot oils, as well as in the lab-prepared and aged samples. These findings indicate that the enantiomeric composition was unaffected by the experimental conditions. In conclusion, based on the enantiomeric excess of (R)-(−)-linalool, the high enantiomeric purity of 29 of commercial bergamot essential oils was confirmed, while the remaining 9 oils did not meet the verification criteria.