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ARS Home » Research » Publications at this Location » Publication #92913
Title: RAPID ANALYSIS OF FATTY ACID/LIPID MIXTURES BY CAPILLARY SUPERCRITICAL FLUID CHROMATOGRAPHY

Author
item Holliday, Russell
item King, Jerry

Submitted to: Supercritical Fluids International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 7/12/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Supercritical fluid chromatography (SFC) continues to grow in recognition as an essential tool in many analytical labs. SFC is considered as a complimentary tool to traditional methods like GC and HPLC because it possesses properties (density, viscosity, and diffusion coefficient) that are intermediate between gases and liquids. Capillary SFC has been used in our labs to rapidly ascertain reaction product profiles from the hydrolysis of vegetable oils in subcritical water to free fatty acids and to quantify the lipid/free fatty acid content in various soapstocks. The separations were performed on a Lee Scientific Series 600 SFC equipped with a Dionex SB-Phenyl-50 capillary column. SFC speciated mixtures contained fatty acid methyl esters, fatty acids, monoglycerides, diglycerides, and triglycerides. Adequate separation was obtained for the different lipid classes, although the monoglycerides produced a trailing peak. This separation allows for the rapid (45 min) monitoring of lipid transformations. The SFC results for total free fatty acid content in soapstock are a few percent lower compared to an official method. This may be because of the inability of SFC to elute the phospholipids with pure carbon dioxide. However, in comparing the methods, the official method can take 5-8 hours to perform, whereas the SFC method takes 45-50 minutes to run. This saves considerable time and can be used to rapidly ascertain the free fatty acid content in soapstock shipments arriving at a plant.