Fast Analysis of Fish Oils and Animal Lipids on the SUPELCOWAX 10 Column

By: Katherine Stenerson, Reporter EU Volume 13

Katherine Stenerson kstenerson@sial.com

Polyunsaturated fatty acids (PUFAs) are found in both fish and land animal food sources. Recent research findings suggest that there are potential health benefits associated with the consumption of certain PUFAs. Specifically, these studies indicate that the omega-3 PUFAs found in fish may lower a healthy individual’s risk of developing cardiovascular disease (1 ). Capillary GC is the analytical method of choice for fatty acids due to its ability to provide high selectivity and resolving power for complex mixtures. Current methodologies for the analysis of fatty acids in food require saponification, and esterification of samples prior to the analysis of methyl esters using a standard polyethylene glycol (PEG) capillary column. The Omegawax™ 250, 320, and SUPELCOWAX™ 10 capillary columns are often used for the analysis of omega-3 and omega-6 PUFAs from fish and animal sources. Polyethylene glycol phase columns such as Omegawax and SUPELCOWAX provide minimal overlap in fatty acid methyl esters (FAMEs) of different carbon chain lengths, and elute FAMEs according to their degree of unsaturation. This provides for good separation of the predominate omega-3 PUFAs C22:6n3 (DHA) and C20:5n3 (EPA), and the predominate omega-6 PUFA C20:4n6 (2 ).

An example of a popular fast GC method is shown in Figure A. An analysis of various natural mixtures containing FAMES on a 0.10mm ID SUPELCOWAX 10 column provides an excellent example of the selectivity of the column. A shorter column with a narrow ID was used in combination with a fast oven ramp rate and hydrogen carrier gas to reduce the average analysis time of 40-45 minutes to just under 5 minutes. The analyses of methylated samples of cod liver and menhaden oil are presented in Figures A and B. The 15m x 0.10mm ID column had resolution comparable to the Omegawax 250 and 320. C20:5n3 (EPA) and C22:6n3 (DHA) were resolved from other sample components, and the analysis demonstrated the high levels of these PUFAs present in marine samples. The analysis also re-vealed the relative differences in the fatty acid compositions between the two types of fish. A FAME sample derived from an animal source is presented in Figure C. This sample shows significantly lower levels of EPA and DHA than the two fish samples, with the omega-6 fatty acid C20:4n6 as the predominate PUFA.

Figure A. Analysis of FAMEs in Cod Liver Oil on the SUPELCOWAX 10, 15m x 0.10mm ID, 0.10μm

Figure B. Analysis of FAMEs in Menhaden Oil on the SUPELCOWAX 10, 15m x 0.10mm ID, 0.10μm

Figure C. Analysis of FAMEs in Menhaden Oil on the SUPELCOWAX 10, 15m x 0.10mm ID, 0.10μm


Fast GC is becoming increasingly popular due to its ability to increase productivity by reducing analysis time. The 15m x 0.10mm ID x 0.10μm SUPELCOWAX 10 can be used for the fast analysis of FAMEs. By employing the principles of fast GC, one can realize a reduction in analysis time as much as 10-fold.

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References

  1. Kris-Etherton, P.M., Harris, W.S., Appel, L.J., Circulation, 106, 2747-2757 (2002.)
  2. Supelco Application Note T394034 (1994.)

For more information request Reproducible Analyses of Omega-3 and Omega-6 Fatty Acid Methyl Esters by Capillary GC, T394034 (APO), and Analyzing Fatty Acids by Capillary Gas Chromatography,

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Trademarks

Agilent - Agilent Technologies
Carbowax, Discovery, Equity, Omegawax, Sigma-Aldrich, SPB, Supelco, SUPELCOWAX - Sigma-Aldrich Co.
Chromosorb - Manville Corp.
Finnigan - Thermo Finnigan, LLC Corp.
OV - Ohio Valley Specialty Chemical Co.
Teflon - E.I. duPont de Nemours

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Patents

SPME - Technology licensed exclusively to Supelco. US patent #5,691,206; European patent #523,092

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