A single-phase spectrophotometric procedure for in situ analysis of free glycerol in biodiesel

► Inexpensive, fast and more environmentally friendly alternative for free glycerol determination in biodiesel ► Analyte extraction, sample clean up and use of toxic organic solvents are avoided. ► Ethanol as common solvent for biodiesel sample and aqueous chromogenic reagents ► It avoids drawbacks by incomplete extraction, analyte losses and sample contamination