Simultaneous analysis of esters and acylglycerols in biodiesel by high-performance liquid chromatography with refractive index detection

ABSTRACT

Currently, gas chromatography (GC) is the most widely used analytical technique to verify the quality of biodiesel in relation to its glyceride and fatty acid methyl ester (FAME) contents, even though its use has some disadvantages, such as damage to the injector and column caused by the presence of trace levels of triacylglycerols in biodiesel, which means the column has to be replaced every 3 months; the need for the sample to be derivatized, which, while improving chromatographic separation, also increases analysis time; and the use of several imported standard solutions. The main aim of this work was to use high-performance liquid chromatography with refractive index detection (HPLC-RI) to simultaneously quantify the glyceride (mono, di, and triacylglycerol) and FAME contents of biodiesel. The proposed method showed satisfactory results when compared with those obtained by the reference method (GC), particularly when these results were within the working ranges of the reference method. The proposed method using HPLC-RI is therefore promising and could potentially be used instead of the reference method, since the results it yielded were statistically equivalent, with 95% confidence, to the results obtained by the reference method (GC) for the nine samples of commercial biodiesel analyzed in this study.

GRAPHICAL ABSTRACT

KEYWORDS:

• Acylglycerols
• analysis
• esters
• high-performance liquid chromatography
• refractive index

Acknowledgments

The authors wish to thank GREENTEC (Laboratório de Tecnologias Verdes) at the School of Chemistry, Federal University of Rio de Janeiro (EQ/UFRJ) for the samples of biodiesel provided.