An improved HPLC method for quantifying phorbol esters in Jatropha curcas seed oils

Jatropha curcas is a widely spread plant, with its seeds being rich in oil. Accurate quantification of the toxic phorbol esters (PEs) present in Jatropha curcas seed oil (JCSO) is crucial for related research endeavors. The commonly used high-performance chromatography (HPLC) method for PEs has constraints such as multi-stage extraction of PEs and the use of a non-appropriate reference standard (12-O-tetradecanoylphorbol-13-acetate, TPA), which fails to account for variations in the absorbance responses of different Jatropha factors. In this study, the partition coefficient (K) was introduced to resolve the problem of insufficient extraction of PEs during sample preparation, while the derived TPA-equivalent transfer factors (δ) were incorporated to address the issue of concentration amplification in the TPA-reference method. The K-assisted, δ-adjusted HPLC method enabled a faster and more accurate determination of PEs in J. curcas products, using the commercially available reference standard of TPA. The experiments successfully isolated and identified 5 Jatropha factors (C1, C2, C3 and C4 + C5). The actual concentrations of these PEs in JCSO were quantified as 0.097, 0.024, 0.016, and 0.014 mg/mL, respectively, using the newly improved HPLC method.