The productivity of biodiesel (%FAMEs) was quantified by methyl heptadecanoate which was applied as an internal standard, which was calculated according to Eq. (1). 250μL of the product and 250μL of methyl heptadecanoate solution (10mgmL−1 hexane) were added to a 2mL vial with uniform mixing. This solution was injected in the gas chromatographic apparatus and each sample was analyzed three times at least. The conversion of rice bran oil (XRBO) and the selectivity of biodiesel (SBiodiesel) are defined by the following Eqs. (2) and (3):