Greener procedures for biodiesel quality control

Biodiesel analysis often requires large amounts of chemicals and organic solvents with consequent generation of large waste volumes. However, several environmentally friendly alternatives have been presented for assay of biodiesel quality control parameters. These approaches include direct analysis with reagentless procedures, improved sample preparation by dilution or analyte extraction with non-toxic solvents, preparation of emulsions or microemulsions, and sample mineralisation under mild conditions as well as strategies for minimization of reagent consumption and waste generation. These greener alternatives are critically reviewed, highlighting the advantages and limitations of each approach in biodiesel analysis. Alternative analytical techniques (e.g. flow analysis and electrochemical detection), predictive studies, and measurement of physicochemical parameters are also discussed.