Abstract: A QuEChERS combined with high performance liquid chromatography (HPLC) method was developed for the rapid determination of natural capsaicin, dihydrocapsaicin and synthetic capsaicin in hot pepper and its products. The samples were extracted with acetonitrile and purified by sequential use of anhydrous magnesium sulfate, octadecylsilane (C18), ethylenediamine-N-propylsilane silica gel (PSA) and graphitized carbon black (GCB). An Agilent Eclipse Plus C18 column (150 mm × 4.6 mm, 5 μm) was used for separation, gradient elution was performed with a mobile phase comprising 0.4% phosphoric acid aqueous solution and 90% acetonitrile in water, and a 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, with determination coefficients (R2) greater than 0.999. The limits of detection (LOD) and quantification (LOQ) of natural capsaicin were 0.014–0.069 mg/kg and 0.046–0.23 mg/kg, respectively. The LOD and LOQ of dihydrocapsaicin were 0.023–0.12 mg/kg and 0.077–0.39 mg/kg, respectively. The LOD and LOQ of synthetic capsaicin were 0.018–0.088 mg/kg and 0.059–0.30 mg/kg, respectively. The recovery rates were 91.6%–117.2% and the relative standard deviation (RSD) were 0.2%–6.1% for dry hot pepper, fresh hot pepper, shiitake mushroom paste with hot pepper and chili oil at three different spiked levels. The developed method is simple, accurate and suitable for the determination of not only dried and fresh hot peppers, but also natural capsaicin, dihydrocapsaicin and synthetic capsaicin in high oil and high protein hot pepper products.

Key words: QuEChERS; high performance liquid chromatography; hot pepper; capsaicin; synthetic capsaicin