Characterization of biodiesel and biodiesel blends using comprehensive two-dimensional gas chromatography

In this work the development of a comprehensive 2-D GC flame ionization detection (GC x GC FID) method for biodiesel fuels is reported. This method is used for the analysis of fatty acid methyl esters (FAMEs) in both biodiesel (B100) and biodiesel blend (135) samples. The separation of FAME was based on component boiling point in the first dimension and polarity in the second dimension by using a BPX5/BP20 column set to provide a measure of 'orthogonality' in the 2-D space. Here the columns are coupled with a cryogenic modulator operating in a novel temperature programmed mode (T-M) whereby the cryotrap is progressively incremented in temperature as the oven temperature is increased. The final method employs eight cryotrap temperature settings. The developed GC x GC method is able to successfully characterize and identify both B100 and B5 FAME components, which are produced from a variety of vegetable oils, animal fats and waste cooking oils, with high precision. The method is capable of analysing FAME with carbon numbers C4-C24, and is particularly suitable to characterize various types of biodiesel, making it possible to differentiate the origin and type of FAME used in the biodiesel samples.