Analyzing biodiesel: Standards and other methods

Biodiesel occupies a prominent position among the alternatives to conventional petrodiesel fuel owing to various technical and economic factors. It is obtained by reacting the parent vegetable oil or fat with an alcohol (transesterification) in the presence of a catalyst to give the corresponding monoalkyl esters, which are defined as biodiesel. Because of the nature of the starting material, the production process, and subsequent handling, various factors can influence biodiesel fuel quality. Fuel quality issues are commonly reflected in the contaminants or other minor components of biodiesel. This work categorizes both the restricted species in biodiesel and the physical properties prescribed by the standards, and details the standard reference methods to determine them as well as other procedures. Other aspects of biodiesel analysis, including production monitoring and assessing biodiesel/petrodiesel blends, are also addressed. The types of analyses include chromatographic, spectroscopic, physical properties-based, and wet chemical methods. The justifications for specifications in standards are also addressed.