Rapid quantitative determination by super(13)C NMR of the composition of acetylglycerol mixtures as byproduct in biodiesel synthesis

Commercially available partly acetylated glycerols (mono- and diacetin) are mixtures of glycerol, 1- and 2-acetylglycerol, 1,2- and 1,3-diacetylglycerol, and triacetin. Diacetin and monoacetin are by-products of the biodiesel and triacetin production using glycerol esterification with acetic acid or...

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Bibliographic Details
Published in:Fuel (Guildford) 2012-02, Vol.92 (1), p.180-186
Main Authors: Casas, Abraham, Ramos, Maria Jesus, Perez, Angel, Simon, Adolfo, Lucas-Torres, Covadonga, Moreno, Andres
Format: Article
Language:English
Subjects:
Acetates
Biodiesel
Byproducts
Glycerols
Hydroxyl groups
Mathematical analysis
Nuclear magnetic resonance
Triacetin
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Summary:Commercially available partly acetylated glycerols (mono- and diacetin) are mixtures of glycerol, 1- and 2-acetylglycerol, 1,2- and 1,3-diacetylglycerol, and triacetin. Diacetin and monoacetin are by-products of the biodiesel and triacetin production using glycerol esterification with acetic acid or triglyceride interesterification with methyl acetate. Usually, primary analytical methods involve chromatography (HPLC or GC), spectroscopy (MS or NIR), and wet chemical techniques (potentiometric, iodometric titration) which are often time-consuming due to sample preparation, extended analysis time and/or complicated data analysis. Moreover, these methods require pure mono- and diacetin as standard, which are commercially unavailable. In this work, a complete super(31)P and super(13)C chemical shift data for glycerol, mono-, di- and triacetin (including isomers) allows for the identification and quantification of these components in the commercial mixtures. This experimental protocol allows for rapid analysis of mixtures that include these six components. Quantitative super(31)P NMR and super(13)C NMR results were validated to those obtained with other analytical methods, such as GC and HPLC-ELSD. super(13)C NMR is preferred due to allows to measure the content of triacetin, which has no free hydroxyl group, and no signal was detected by super(31)P NMR.
ISSN:0016-2361
DOI:10.1016/j.fuel.2011.06.061