Method validation for analysis of phorbol esters from Jatropha curcas

Abstract

Jatropha curcas is a promising non-food source of oil for biodiesel. However, the presence of phorbol esters (PE) is the main limiting factor for utilization of defatted cakes for animal feed. Reliable methods of analysis and quantification of phorbol esters are useful for plant breeding research as well as for detoxification process. Analytical methods for PE extraction show different conditions, temperatures, contact times, solvents and mass/solvent ratio. In this work, methanol and dichloromethane were evaluated as extraction solvent, and Soxhlet, ultrasound and stirring assisted extractions at different times of contact were compared. The quantification was performed by HPLC-DAD. Methanol was more efficient for exhaustive J. curcas PE extraction as compared to dichloromethane. Among the evaluated extraction methods, Soxhlet extraction with methanol during 6 h was the most efficient to quantify PE, showing RSD (Relative Standard Deviation) varying from 3 to 5%. The validated method showed limits of detection and quantification of 0.48 and 1.4 μg, respectively, with good linearity and precision. The specificity of the method was confirmed by LC–MS/MS and UV spectra data using three different columns and mobile phases.