Abstract: A QuEChERS method combined with high performance liquid chromatography was developed for the rapid determination of natural capsaicin, dihydrocapsaicin and synthetic capsaicin in capsicum and its products. The samples were extracted with acetonitrile and purified with anhydrous magnesium sulfate, octadecylsilane (C18), n-propyl ethylenediamine (PSA) and graphitized carbon black (GCB). Agilent Eclipse Plus C18 (4.6×150 mm, 5 μm) was used for separation, gradient elution was performed with 0.4% phosphoric acid aqueous solution and 90% acetonitrile as mobile phase, and fluorescence detector was used for detection. The results showed that natural capsaicin, dihydrocapsaicin and synthetic capsaicin had a good linear relationship in the range of 0.20~100 mg/L, and the correlation coefficient (R2) was greater than 0.999. The limits of detection and quantification of natural capsaicin were 0.014~0.069 mg/kg and 0.046~0.23 mg/kg respectively. The limits of detection and quantitation of dihydrocapsaicin were 0.023~0.12 mg/kg and 0.077~0.39 mg/kg respectively. The detection limits of synthetic capsaicin were 0.018~0.088 mg/kg, and the limits of quantification were 0.059~0.30 mg/kg. The recoveries were 91.6%~117.2% and the relative standard deviations were 0.2%~6.1% in the 4 substrates of dry pepper, fresh pepper, mushroom paste and chili oil under 3 different supplemental levels. The method is simple, accurate and suitable for the determination of natural capsaicin, dihydrocapsaicin and synthetic capsaicin in high oil and high protein pepper products.

Key words: QuEChERS, High performance liquid chromatography, Capsicum, Capsaicin, Synthetic capsaicin