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The Joint Research Centre (JRC) is the European Commission's science and knowledge service which employs scientists to carry out research in order to provide independent scientific advice and support to EU policy.
Biodiesel is obtained by transferring vegetable oils or animal fats into alkyl esters of their fatty acids. However, the amount of free glycerol as a by-product of the biodiesel production, together with remaining amounts of unreacted triacylglycerides and partially reacted mono- and diacylglycerides, play an important role for the fuel quality. These compounds should be absent in the ideal case.
Read more in: L.R. Miguel et al., On-line hydrogenation of biodiesel – toward a reference method for the determination of glycerides and total glycerol, J. Chromatogr. A, doi: 10.1016/j.chroma.2014.02.040 (2014)