Determination of free glycerol in biodiesel

Within the biodiesel production process, glycerol arises as a side product. This free glycerol is included also in biodiesel in a small amount. Several methods are known to determine it. Some of them are based on the GC. In this paper a new method is introduced, which is based on the extraction of free glycerol into water and its subsequent determination in water solution by HPLC with refractometric detection. The comparison of GC and HPLC methods led to the same results. The new method is reliable and comparatively fast for determination of free glycerol in biodiesel