Quantitative determination of sweet orange, lime, and grapefruit essential oil adulterants in lemon essential oil (Citrus limon L.) using attenuated total reflectance fourier transform infrared spectroscopy and chemometrics

The high market value of certain essential oils (EOs), such as lemon essential oil (LEO), makes them particularly susceptible to adulteration. Such adulteration typically involves the intentional addition of low-value EOs. In this study, we mixed LEO and sweet orange essential oil (SOEO), lime essential oil (LiEO), and grapefruit essential oil (GEO) at varying concentrations. We then used Attenuated Total Reflectance–Fourier Transform Infrared Spectroscopy (ATR-FTIR), and principal component regression (PCR), partial least squares regression (PLS), and artificial neural network (ANN) chemometrics to quantify adulteration in the samples. The ANN models produce the best accuracy, however it is computationally expensive and not practical. We further demonstrate that PLS using the 2000–1000 cm−1, ATR-FTIR spectral region produces good accuracy in predicting % v/v LEO, SOEO, LiEO, and GEO in the samples.