Kinetics of rancidity: ¹H-NMR fingerprinting-based photodegradation monitoring of citronella oil

ABSTRACT

Although known as a natural mosquito repellent, especially in the tropical region, citronella oil has many other therapeutic properties including antimicrobial and antifungal. Citronella oil can be applied in pure form or as a component in different cosmetic products. As with other essential oils, citronella has specific storage conditions to prevent its rancidity. ¹H-NMR fingerprinting was used to monitor the changes in the concentration of citronellal, the main component of citronella oil. Quantitative analysis of the ¹H-NMR spectral data digitized the degradation pattern of citronellal to determine the effect of sunlight exposure. Significant spectral changes were observed in clear glass vials starting from the 7^th day of sun exposure. The degradation of citronellal followed first-order kinetics with a half-life of 15.7 ± 2.9 days. Moreover, the effect of sunlight exposure to citronellal is highly apparent in clear glass vials than in amber glass vials. The results of this study supported the general storage condition for essential oils to maximize shelf life.

KEYWORDS:

• Citronellal
• citronella oil
• qNMR
• photodegradation

Acknowledgments

The authors would like to acknowledge the NMR Facility of the Institute of Chemistry, University of the Philippines Diliman for the use of the needed equipment. This work was funded by the UP System Enhanced Creative Work and Research Grant (ECWRG-2022-2-5 R).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the University of the Philippines [ECWRG-2022-2-5 R].