Quality parameters evolution during biodiesel oxidation using Rancimat test

A study was carried out in order to evaluate the evolution of peroxide value, anisidine value, kinematic viscosity at 40 degreesC, ester and linolenic acid content, UV absorbency, acid value, polymer and tocopherol content during the oxidation of fatty acid methyl ester (FAME) using the Rancimat test chosen by CEN for measuring oxidation stability of FAME (pr EN 14112). The oxidation curves obtained during Rancimat test were compared with those obtained by the variation of oxidation parameters mentioned above, against the time. All quality parameters studied present visible variation along Rancimat test except UV 270 nm. At the end of Rancimat induction period, the seven samples tested do not meet FAME or oils and fats specifications such as kinematic viscosity, acid value, ester content or peroxide value. Rancimat induction period is well correlated to induction period given by quality parameters (0.963<R-2<0.999), but Rancimat induction period is almost 10% higher than induction period given by quality parameters. Main conclusion is that induction period determined by conductivity is well correlated to degradation of quality parameters along Rancimat test.