An Innovative Approach for the Detection of High Boiler Adulterants in Sandalwood and Cedarwood Essential Oils

Abstract

Owing to the important uses of essential oils, its adulteration is a serious issue of concern. Among the adulterants, the high volatiles can be detected through GC and GC/MS. However, the detection of subtle high boiler adulterants is extremely difficult, and requires development of novel techniques to overcome the challenges faced by the essential oil industry. In current study, the thermogravimetric analysis (TGA) was validated as an innovative approach for quantitative estimation of adulteration in essential oils taking sandalwood and cedarwood oils as case study. The low−cost vegetable oils like castor oil, coconut oil, and synthetic polymer like polyethylene glycol-400 (PEG-400) were used as high boiler adulterants. The physical parameters like specific gravity and refractive index of pure and adulterated oil samples were analyzed followed by their TGA analysis. The physical parameters of adulterated samples did not show significant variation from that of pure essential oils, thus need alternate analytical techniques to overcome this issue. The TGA of pure essential oil was volatized in single−stage around 200–260℃, whereas the high boiler adulterants such as vegetable oils and synthetic PEG-400 majorly volatized in the range 300–500℃ and 260–400℃, respectively. The adulterated samples exhibited mostly two-stage weight loss pattern, which was quantitatively estimated with high accuracy by this technique. Therefore, the TGA analysis can be used as a novel technique for rapid and precise detection of high boiler adulterants in essential oils like sandalwood and cedarwood due to difference in their volatile behaviour.