Determination of polar impurities in biodiesels using solid-phase extraction and gas chromatography–mass spectrometry

✍ Scribed by Zeyu Yang; Bruce P. Hollebone; Zhendi Wang; Chun Yang; Mike Landriault

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 260 KB
• Volume: 34
• Category: Article
• ISSN: 1615-9306
• DOI: 10.1002/jssc.201000533

✦ Synopsis

Determination of polar impurities in biodiesels using solid-phase extraction and gas chromatography-mass spectrometry

This paper reports on a method for development and validation for simultaneous characterization and determination of oxygenated polar impurities -free fatty carboxylic acids (FFAs), partial glycerides (monoacylglycerides, MGs), residual glycerol and free sterolsin various biodiesels based on the combination of solid-phase extraction (SPE), silylation and GC/MS technologies. The effects of various SPE and silylation conditions on the method recoveries were evaluated. Using this integrated SPE-GC/MS method, 38 target polar compounds (13 FFAs, 17 glycerides and 8 sterols) in 9 biodiesels derived from 4 different feedstocks were successfully separated and quantified. It was found that the carbon chain length of FFAs was ranged from C 6 to C 24 , with C 16 and C 18 being the most abundant in all biodiesels. The total FFAs concentration was consistent with the acid values (AVs) measured by standard method ASTM D974-04. MG congeners with carbon number of 18 (mono-C18) were most abundant in the biodiesel samples, followed by mono-C 16 and free glycerol. b-Sitosterol and campesterol were found to be the prevailing phytosterols in all pure vegetable oil-based biodiesels, while brassicasterol and stigmasterol was only significant in the biodiesel from canola oil and soybean oil, respectively, and abundant cholesterol was only detected in animal fat-based biodiesels.