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Separation of acylglycerols, FAME and FFA in biodiesel by size exclusion chromatography
Author(s) -
Kittirattanapiboon Kanisa,
Krisnangkura Kanit
Publication year - 2008
Publication title -
european journal of lipid science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.614
H-Index - 94
eISSN - 1438-9312
pISSN - 1438-7697
DOI - 10.1002/ejlt.200700164
Subject(s) - chemistry , glyceride , chromatography , acetone , acetic acid , biodiesel , dichloromethane , solvent , toluene , size exclusion chromatography , fatty acid methyl ester , methanol , tetrahydrofuran , fatty acid , elution , organic chemistry , catalysis , enzyme
Abstract Size‐exclusion chromatography separates solutes according to their molecular sizes. Free fatty acids (FFA), fatty acid methyl esters (FAME) and monoacylglycerols (MG) of vegetable oils or animal fats have very close molecular sizes and they cannot be baseline‐separated on a single Phenogel column (100 Å, 300 mm × 7.8 mm ID, 5 µm) by using tetrahydrofuran (THF) as the mobile phase. When toluene is used as the mobile phase, triacylglycerols (TG), diacylglycerols (DG), MG and FAME are well separated but there is no baseline resolution between DG and FAME. In addition, the elution order of MG and FAME is reversed. However, baseline separation of all the above lipid classes can be achieved by using toluene containing THF, acetone, dichloromethane, ethyl acetate or acetic acid as the solvent modifier. Acetic acid (0.25%) as the solvent modifier gives the best resolution and all the reference peaks are symmetrical. The detection limit of each class of lipids is 0.1 µg. The correlation coefficient values (between 1 and 100 µg) of all the lipid classes are better than 0.99. Thus, the determination of biodiesel products in the biodiesel reactor is very much simplified.