Feasibility of near-infrared spectroscopy and chemometrics analysis for discrimination of Cymbopogon nardus from Cymbopogon citratus

Abstract

The authenticity of essential oils has become an important issue in supplying essential oil raw materials for the pharmaceutical, perfume, and cosmetic industries. Citronella oil is one of the essential oils used in those industries. Cymbopogon nardus is one of the lemongrass species that can produce citronella oil. However, with the high price of citronella oil from C. nardus, there is a possibility of being substituted or adulterated with closely related plants, namely Cymbopogon citratus. This paper described the feasibility of near-infrared (NIR) spectroscopy combined with chemometrics analysis for rapid identification and authentication of C. nardus from C. citratus essential oil. NIR spectra of both essential oils and their mixture (10 % and 25 % v/v of C. citratus in C. nardus) showed a similar spectral profile, so we cannot easily discriminate them and need help from chemometrics analysis. For chemometrics analysis, we used absorbance data from the preprocessed NIR spectra at wavenumbers 4000–6500 cm−1. Using PCA, we could separate each essential oil from C. nardus and C. citratus but cannot discriminate between 10 % and 25 % of CC in CN. While using OPLS-DA with R2X(cum) = 0.88, R2Y(cum) = 0.859 and Q2(cum) = 0.723, we could group each sample. The OPLS-DA score plot clearly shows the difference between C. nardus and C. citratus essential oils and their mixtures. The combination of NIR and OPLS-DA could provide a suitable method for identifying and authenticating C. nardus from C. citratus essential oil.