No abstract

An electroenzymatic method based on two coupled enzymatic activities (glycerokinase and glycerol-3-phosphate oxidase) was developed using a platinum microelectrode for the determination of free glycerol in biodiesel samples. The electroenzymatic method proposed showed a good linear correlation coefficient (R = 0.9894), with a linear response in the concentration range of 8.2 9 10 -5 to 5.7 9 10 -4 % (w/w) and a limit of detection of 6.0 9 10 -5 % (w/w). The results obtained for the free glycerol content of select biodiesel samples were compared with their gas chromatography (GC) analyses. The relative errors for glycerol determination using this enzymaticamperometric method were in the range of -8.0 to 3.0%. The proposed method was shown to be promising for the analysis of glycerol in biodiesel samples and a simple and inexpensive method in comparison to gas chromatography.