Vibrational spectroscopy and chemometric modeling: An economical and robust quality control method for lavender oil

Abstract

Lavandula species (Lamiaceae), commonly known as lavender, ranks among the top 10 medicinal plants used worldwide and is used and traded extensively in the flavor and fragrance, cosmetic, and aromatherapy industries. Many studies continue to confirm the phytotherapeutic potential of lavender oil in the treatment of wounds, rheumatism, muscular pains, dermatitis, acne, and eczema amongst many others. Gas chromatography coupled to mass spectrometry with a flame ionization detector (GC–MS–FID) is the conventional method for the quality assessment of lavender oil. In this study, vibrational spectroscopy methods such as mid infrared (MIR) and near infrared (NIR) in tandem with chemometric data analysis are proposed as alternative methods for the routine quality control of this commercially important essential oil. Sixty lavender oil samples were purchased from a wide range of suppliers and six major and minor compounds (1,8-cineole, (E)-β-ocimene, (Z)-β-ocimene, camphor, linalool, and linalyl acetate) were quantified using GC–MS–FID (reference data). Spectral data was acquired for both MIR (4000–550cm−1) and NIR (10000–4000cm−1) wavelength regions and chemometric modeling applied to develop calibration models. The calibration models revealed good statistical performance where the coefficients of determination obtained for the major compounds of lavender oil were ≥0.82. Good coefficients of determination were observed for linalool R2=0.99 (MIR) and 0.98 (NIR), as well as linalyl acetate R2=0.92 (MIR) and 0.90 (NIR). Linalool and linalyl acetate represented about 70% of the total composition of the essential oil. Low values (≤1.6) were obtained for the root mean square error of estimation (RMSEE) and root mean square error of prediction (RMSEP). The external dataset was accurately predicted as evidenced by comparison with the reference data.