VALIDATION OF A METHOD FOR DETERMINATION OF FREE GLYCEROL IN BIODIESEL

In this study, validation of a method for determination of free glycerol from biodiesel samples by using gas chromatography coupled with flame ionization detector (GC-FID) and the measurement uncertainty estimation was described. The derivatization reaction with N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA) was used to volatilize the glycerol prior to GC analysis. The 1,2,3-butanetriol was used as internal standard. Linearity, limit of detection, limit of quantification, precision and accuracy of the method were determined for the validation of the method. The limit of detection, estimated from chromatograms was 0.0006 % (w/w), while limit of quantification was 0.002 % (w/w). The recovery of free glycerol was determined by using certified reference material (CRMs) and was 102.4 +/- 13.0 %. Also, the measurement uncertainty was estimated based on the bottom-up approach. The expanded uncertainty of the determination of free glycerol from biodiesel by GC-FID method was 16%.