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Determination of polar impurities in biodiesels using solid‐phase extraction and gas chromatography–mass spectrometry
Author(s) -
Yang Zeyu,
Hollebone Bruce P.,
Wang Zhendi,
Yang Chun,
Landriault Mike
Publication year - 2011
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.201000533
Subject(s) - chemistry , chromatography , solid phase extraction , stigmasterol , glyceride , silylation , extraction (chemistry) , glycerol , mass spectrometry , biodiesel , gas chromatography–mass spectrometry , vegetable oil , gas chromatography , campesterol , fatty acid , organic chemistry , sterol , biochemistry , cholesterol , catalysis
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 sterols – in 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. β‐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.