Raman spectroscopy in the detection of adulterated essential oils: The case of nonvolatile adulterants
Journal
Journal of Raman Spectroscopy
ISSN
1097-4555
Date Issued
2021-03-04
Author(s)
Paul Vargas Jentzsch
Christian Sandoval Pauker
Paola Zárate Pozo
Marco Sinche Serra
Gonzalo Jácome Camacho
Victor Rueda‐Ayala
Luis Ramos Guerrero
Valerian Ciobotă
Abstract
<jats:title>Abstract</jats:title><jats:p>Essential oils are liquid mixtures of volatile compounds extracted from plants. Their quality is usually controlled via gas chromatography (GC), although with limitations when adulterants are nonvolatile substances. The essential oils of lavender (<jats:styled-content style="fixed-case"><jats:italic>Lavandula angustifolia</jats:italic></jats:styled-content> Mill.), peppermint (<jats:italic>Mentha piperita</jats:italic> L.), patchouli (<jats:styled-content style="fixed-case"><jats:italic>Pogostemon cablin</jats:italic></jats:styled-content> Benth), and their adulterated versions were measured by GC coupled to flame ionization detector (GC‐FID) and Raman spectroscopy. Canola oil, a nonvolatile substance, was used as the adulterant. The adulterated essential oils contained 1%, 3%, 5%, 10%, 15%, and 20% (v/v) of canola oil. Chromatograms of the adulterated essential oils containing 20% (v/v) of canola oil showed decrements in peak areas of the essential oil components, compared with peaks of the pure essential oils. The highest decrements were observed for the adulterated essential oil of patchouli. In general, detection of adulterated essential oils by simple visual inspection of the Raman features was difficult, due to slight differences observed in the spectra. Principal Components Analysis (PCA) allowed achieving a good spectral discrimination between pure and adulterated essential oils. These results suggest that Raman spectroscopy can overcome limitations of GC‐based methods, thus becoming an interesting alternative and complementary technique for quality control of essential oils.</jats:p>