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ARS Home » Research » Publications at this Location » Publication #70549
Title: QUALITATIVE AND QUANTITATIVE DETERMINATION OF METHYL ESTERS, FREE FATTY ACIDS, MONO-, DI-, AND TRIGLYCERIDES VIA HIGH PERFORMANCE LIQUID CHROMATOGRAPHY COUPLED WITH A FLAME IONIZATION DETECTOR

Author
item Neff, William
item Jackson, Michael
item List, Gary
item King, Jerry

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Knowledge of the amounts and types of the components in products like margarine candidates produced from fats like soybean oil are important for a number of reasons. These components are called tri, di and mono glycerides and free fatty acids. The components effect the fat product physical properties, such as melting point, texture, and even resistance to oxidation. For margarine candidate studies, it is important to be certain the product is free of the components, except for triglycerides. We have developed an analytical method, which utilizes a technique called high performance liquid chromatography coupled with a device called a flame ionization detector. The technique can identify and quantitate the fat components. This analytical technique can assist industry in the production of fat products free of all but triglycerides for margarine candidates. Also, in some fat products, mono and diglycerides in addition to triglycerides are beneficial. For these products, the analytical technique can allow industry to optimize the composition of these components to produce products beneficial to the consumer.

Technical Abstract: High Performance Liquid Chromatography (HPLC) with a cyano phase column and a gradient mobile phase of methyl tert-butyl ether and hexane and a flame ionization (FID) detector proved successful to separate and quantitate mono, di and triglycerides, free fatty acids and methyl esters. These components can occur together during glycerolysis, lipolysis, randomization and interesterification reactions of vegetable oils like soybean. Gravimetric standards were evaluated by HPLC-FID in which each contained mono, di, and triglycerides, free fatty acids and methyl esters of palmitic, stearic, oleic, linoleic and linolenic acids respectively. The resolution of these components was better accomplished on a polar or cyano phase instead of a nonpolar or hydrocarbon phase HPLC column. The elution time for the components resolved on the cyano column increased in this order: methyl esters, triglycerides, free fatty acids, 1,3-diglycerides, 1,2-diglycerides, 1-monoglycerides and 2-monoglycerides respectively. The FID response with solute weight decreased in this order: triglycerides, free fatty acids, diglycerides, methyl esters, and monoglycerides respectively. The HPLC-FID detector required response factors to quantitate the components of mixtures of diverse lipid molecular species.