Fate of toxic phorbol esters in Jatropha curcas oil by a biodiesel fuel production process.

Biodiesel fuel (BDF) is an important alternative fuel because of the carbon neutral nature of biomass and the exhaustion of fossil fuel resources. Jatropha curcas oil (JCO) produced from J. curcas seeds contains toxic phorbol esters that can cause cancer. The behaviors of toxic phorbol esters were investigated during BDF production. Liquid chromatography-tandem mass spectrometry and photodiode array analyses revealed that the phorbol esters contained in JCO had a tigliane skeleton. The partition coefficients of phorbol esters between methanol (MeOH) and the oil (K) ranged from 2.4 to 20. As a result, the phorbol esters in the JCO were largely partitioned into the MeOH phase. The phorbol esters in the oil were converted stoichiometrically into phorbol and the corresponding fatty acid methyl esters via a transesterification reaction in a potassium hydroxide (KOH)/methanol (MeOH) solution. The phorbol produced predominantly partitioned into the glycerin phase. A small amount of phorbol residue contained in the BDF could be removed by washing with water. These results suggest that it is safe to use BDF produced by the aforementioned transesterification reaction and purification process. However, phorbol contamination of glycerin and wastewater from the production process should not be ignored. [ABSTRACT FROM AUTHOR]

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