Detection of the presence of used frying oil as raw material in biodiesel production

Abstract

The detection of compounds giving information on the use of used frying oils as raw material in the production of biodiesel is of interest to guarantee the quality of the product. In this study, the most characteristic groups of compounds formed after used frying oil transesterification were analyzed by means of the standard technique using gas chromatography at a high temperature (EN 14105). Dimeric fatty acid methyl esters (dimeric FAME) is the most important group to be considered as they are present in significant amounts after used frying oil transesterification. On the other hand, they are absent in the bleached oils used for biodiesel production. The concentration of the dimeric FAME in the polar fraction of biodiesel, easily obtained by adsorption chromatography, allowed detection of this group of compounds even in very low concentrations.