Effects of Weathering on Sterol, Fatty Acid Methyl Ester (FAME), and Hydrocarbon Profiles of Biodiesel and Biodiesel/Diesel Blends

The weathering of biodiesel and biodiesel/diesel blends was investigated to determine the changes in the profiles of fatty acid methyl esters (FAMEs), sterols, and hydrocarbons. Sterols were more persistent than FAMEs and are better candidates for identifying biodiesels in environmental media and for determining the source of a biodiesel spill. The changes in FAME and sterol profiles over time are discussed. In biodiesel blends, accelerated weathering was observed for pyrene, fluoranthene, and their alkyl homologues compared to diesel. FAME and sterol analysis should be performed in addition to hydrocarbon profiling to distinguish between a weathered diesel and a weathered biodiesel/diesel blend.