We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Determination of Free Fatty Acids and Triglycerides by Gas Chromatography Using Selective Esterification Reactions.
- Authors
Kail, Brian W.; Link, Dirk D.; Morreale, Bryan D.
- Abstract
A method for selectively determining both free fatty acids (FFA) and triacylglycerides (TAGs) in biological oils was investigated and optimized using gas chromatography after esterification of the target species to their corresponding fatty acid methyl esters (FAMEs). The method used acid catalyzed esterification in methanolic solutions under conditions of varying severity to achieve complete conversion of more reactive FFAs while preserving the concentration of TAGs. Complete conversion of both free acids and glycerides to corresponding FAMEs was found to require more rigorous reaction conditions involving heating to 120°C for up to 2 h. Method validation was provided using gas chromatography–flame ionization detection, gas chromatography–mass spectrometry, and liquid chromatography–mass spectrometry. The method improves on existing methods because it allows the total esterified lipid to be broken down by FAMEs contributed by FFA compared to FAMEs from both FFA and TAGs. Single and mixed-component solutions of pure fatty acids and triglycerides, as well as a sesame oil sample to simulate a complex biological oil, were used to optimize the methodologies. Key parameters that were investigated included: HCl-to-oil ratio, temperature and reaction time. Pure free fatty acids were found to esterify under reasonably mild conditions (10 min at 50°C with a 2.1:1 HCl to fatty acid ratio) with 97.6 ± 2.3% recovery as FAMEs, while triglycerides were largely unaffected under these reaction conditions. The optimized protocol demonstrated that it is possible to use esterification reactions to selectively determine the free acid content, total lipid content, and hence, glyceride content in biological oils. This protocol also allows gas chromatography analysis of FAMEs as a more ideal analyte than glyceride species in their native state.
- Subjects
FATTY acids; TRIGLYCERIDES; ESTERIFICATION; ESTERS; FATS &; oils; GAS chromatography/Mass spectrometry (GC-MS)
- Publication
Journal of Chromatographic Science, 2012, Vol 50, Issue 10, p934
- ISSN
0021-9665
- Publication type
Article
- DOI
10.1093/chromsci/bms093