The choice of the vegetable oils mentioned above is justified by the fact that the regulation of biodiesel production in Brazil [8] does not restrict the use of vegetable oils. Further, the Brazilian laws also provides taxes benefits for those that produce biodiesel using vegetable oils produced by familiar agriculture (babassu, for instance). In this sense it is important to have fast, precise, and accurate analytical methods that can detect methyl esters from different sources in the biodiesel blends in order to avoid fiscal frauds.