Vibrational Spectroscopic Methods for the Identification and Distinction of Essential Oils in Genus Ocimum L.: A Chemometric Approach

Essential oils are mainly analyzed by gas chromatography coupled with mass spectrometry (GC–MS). This is a time consuming technique which requires complex instrumentation assembly. Raman and FTIR spectroscopy are rapid and non-destructive techniques for qualitative characterization, differentiation of principal essential oil components, detection of adulteration in the oil, quality control of essential oil in industry as well as to distinguish different taxa. In the present study, five Ocimum spp. (Ocimum tenuiflorum L., Ocimum gratissimum L., Ocimum × africanum Lour., Ocimum basilicum L. and Ocimum americanum L) have been identified on the basis of essential oil by the Raman and FTIR spectroscopic techniques. It was found that methyl eugenol, eugenol, estragole, and camphor are major essential oils components present in Ocimum L. The results of PCA indicate that all five species of Ocimum L. form different clusters on the basis of principal essential oil components. The components of essential oil predicted by Raman spectroscopy correlate well with that of FTIR data. The present study demonstrates the use of Raman and FTIR spectroscopy techniques to distinguish taxa and characterization of essential oil components.