The FAME concentration expressed as the biodiesel purity of the product was determined by gas chromatography (Thermotrace GC ultra, Thermo Co.) equipped with a flame ionization
detector, a capillary column (Tr-biodiesel (F), Thermo Co., 30 m in length with 0.25 mm i.d. and 0.25 mm film thickness), the programmed column oven, and a programmed temperature
injector.