Biodiesels were prepared using base catalyzed methanolysis of sunflower, soybean and canola oils.
Rancimat oxidative stability measurements showed that the induction period (IP) for neat canola biodiesel
conformed to EN 14214, the European specification for biodiesel (IP > 6 h). Stability was enhanced
when 0.5 wt.% of the synthetic antioxidants di-tert-butylhydroquinone (DTBHQ) or poly(1,2-dihydro-
2,2,4-trimethylquinoline) (Orox PK) was added. Soybean-based biodiesel spiked with 0.5 wt.% DTBHQ
also reached this specification. Orox PK improved the stability of sunflower biodiesel but the 3 h induction
period specified by ASTM D-6751 could not be reached. Curiously, canola biodiesel was destabilized
on adding the antioxidant Naugard P (tris(nonylphenyl) phosphite).