Analysis of processed soy oil by gas chromatography

Abstract

Two basic gas chromatographic approaches are currently used for the analysis and characterization of processed soy oil and other lipid materials. One approach separates the intact glycerides after silylation whereas the complementary approach determines the fatty acid composition of the glycerides by the formation and subsequent separation of the corresponding fatty acid methyl esters. A brief history of the development of these gas chromatographic procedures and a more detailed discussion of current packed and capillary column technology used for the separation of both intact glycerides and fatty acid methyl esters is presented. Emphasis is placed on the advantages of the newly emerging capillary techniques over the more conventional packed column separations. High resolution chromatograms are shown for the separation of mixed glyceride isomers and also for the separation of unsaturated methyl esters with respect to the number, geometry and position of the double bonds. The separation of the methyl esters can provide information equivalent to classicalcis,cis‐lipoxygenase, iodine monochloride titration and infraredrans analyses. Finally, the use of short capillary columns to achieve rapid low cost separations (with resolution equivalent to packed column separations), ideal for quality control, also are discussed.

Rapid determination of free fatty acids in vegetable oils by gas liquid chromatography

“…The modified BF3/MeO}t esterification procedure used was as described by Chapman (4). The modified BF3/MeO}t esterification procedure used was as described by Chapman (4).…”

“…The titration procedure used was the AOCS Official Method Ca 5a-40 (1). The modified BF3/MeO}t esterification procedure used was as described by Chapman (4).…”

“…Of the many procedures developed for the determination of free fatty acids in vegetable oils, there are only three noted in the literature which measure the individual free fatty acids: separation of underivatized free fatty acids on gas chromatographic columns (2); a BF3/MeOH esterification procedure (3); and a new procedure using BSTFA that measures not only the free fatty acids but the mono-, di-and triglycerides as well (4). Gas chromatographic columns which separate underivatized fatty acids are impractical due to the shortened column life resulting from repeated injections of vegetable oil onto the column.…”

“…The various compounds formed in meats (1-12), triglycerides (2,4,5,9,(12)(13)(14)(15)(16)(17)(18)(19)(20)(21), fatty acids and fatty acid esters (4,9,12,(16)(17)(18)(20)(21)(22)(23)(24)(25) have been well characterized by qualitative analysis employing mainly mass spectrometry (MS). Quantitative methods have also been devised (1,3,9,12,(26)(27)(28)(29) allowing determination of the relative amounts of these components, and the reaction pathways have been adduced or proposed (16,17,19,30).…”

Beyond diazomethane: Alternative approaches to analyzing non‐esterified fatty acids

“…Unfortunately, TMS esters and ethers are hydrolytically unstable and may only be stored for 24–72 h before noticeable degradation occurs . Nonetheless, silylation is a simple and versatile approach with broad applications which D'Alonzo et al demonstrated by separation of NEFA from intact glycerides following silylation of soy bean oil lipid extracts.…”