Free and Total Glycerin in Biodiesel: Accurate Quantitation by Easy Ambient Sonic-Spray Ionization Mass Spectrometry

• Published in: Energy & fuels Vol. 26; no. 5; pp. 3042 - 3047
• Main Authors: Fernandes, Anna Maria A. P, Tega, David U, Jara, Jose L. P, Cunha, Ildenize B. S, de Sá, Gilberto F, Daroda, Romeu J, Eberlin, Marcos N, Alberici, Rosana M
• Format: Journal Article
• Language: English
• Published: American Chemical Society 17-05-2012
• Subjects: Biodiesel; Desorption; Flame ionization; Fuels; Ionization; Mass spectrometry; Regulatory agencies; Spectroscopy
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/ef300399m

Quantitation of free and total glycerin content in biodiesel is performed via a simple and direct ambient desorption/ionization mass spectrometric technique. Easy ambient sonic-spray ionization mass spectrometry (EASI–MS) is applied to either the crude or derivatized sample spiked with an internal standard allowing for immediate quantitation of free and total glycerin, a major quality parameter for biodiesel. The linear range obtained by EASI–MS for free glycerin was from 0.005 to 0.100% (m/m), and that for bound glycerin (mono-, di-, and triacylglycerides) was from 0.01 to 0.50% (m/m). These values are in concordance with those required by major regulatory agencies for biodiesel quality control, which are, for free glycerin, a 0.02% (m/m) maximum and, for total glycerin, a 0.25% (m/m) maximum. The simple and fast EASI­(+)–MS protocol seems to offer a proper substitute or alternative for the more demanding and time-consuming gas chromatography with flame ionization detection (GC–FID) standard methodology.