Characterization of fatty acid methyl esters in biodiesel using high-performance liquid chromatography

This study presents a new method for characterizing the composition of a biodiesel that is composed of fatty acid methyl esters (FAMEs) with high-performance liquid chromatography (HPLC). The chromatographic peaks of methyl palmitate (MP) and methyl oleate (MO), which are the main FAMEs, usually overlap chromatographically in the HPLC analysis. HPLC shows poor performance for the separation of MP and MO, even by applying a gradient elution program, and is difficult to use for the accurate quantification of MP and MO. A mathematical method has been developed to estimate the individual masses of MP and MO from their overlapping peaks in the HPLC chromatogram with refractive index (RI) and ultraviolet (UV) detectors in series. As a result, the individual masses of MP and MO in the artificial mixtures can be quantified accurately. Furthermore, FAME composition and the yield of the biodiesel that was obtained from the transesterification of soybean oil were quantified for verification in this study. Therefore, the present approach can provide useful information to precisely estimate the FAME composition in biodiesels with the employment of HPLC.

► A mathematical method is developed for the HPLC with refractive index and ultraviolet detection in series.
► Estimate individual masses of methyl palmitate and methyl oleate from their overlapping peaks in HPLC.
► The FAME composition and transesterification yield estimated by present method are consistent with those obtained in the literatures and 1H NMR analysis.