Fast simultaneous determination of capsaicin, dihydrocapsaicin and nonivamide for detecting adulteration in edible and crude vegetable oils by UPLC-MS/MS

ABSTRACT

Capsaicinoids are pungent components in hot peppers, which have been detected in waste cooking oil. However, trace analysis of capsaicinoids in edible and crude vegetable oils is a challenging task due to the complex matrix. In this study, a simple liquid-liquid extraction and solid phase extraction (SPE) coupled with RP-UPLC-ESI-MS/MS method was developed for the quantification of capsaicinoids in edible and crude vegetable oils to screen the adulteration with waste cooking oil. This method was used to simultaneously determine 3 capsaicinoids (capsaicin, dihydrocapsaicin, and nordihydrocapsaicin) with capsaicin-d₃, and dihydrocapsaicin-d₃ as internal standards. This method allows the complete analysis of a sample in only an hour, even including sample preparation and chromatographic separation. The linear range of 3 capsaicinoids ranged between 0.5 and 40 µg/kg. The limit of detection (LOD) and limit of quantification (LOQ) for capsaicinoids were calculated as 0.15 and 0.5 µg/kg, respectively. Quantitative recoveries ranging from 92.9% to 105% were obtained by the analysis of spiked oil. The relative standard deviations were less than 5% (n = 6). The established method can potentially overcome the interference of triacylglycerols and fatty acids in edible and crude vegetable oils, and have been successfully applied to analyse real oil samples. This method provided a rapid and reliable method for the detection of adulteration of vegetable oils with waste cooking oils.

KEYWORDS:

• Capsaicinoids
• waste cooking oil
• adulteration
• RP-UPLC-MS/MS

Acknowledgments

We would like give our sincere gratitude and thanks to Yihai Kerry group for financial and samples support. We would also like to thank Karuno Wong Song Yao (Republic Polytechnic) for his hard work and support for helping with some parts of the experiment process.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Wilmar (Shanghai) Biotechnology Research & Development Center Co., Ltd.