A Capillary GC Determination of Cyclopropenoid Fatty Acids in Cottonseed Oils

Abstract

A capillary gas chromatography (GC) method was studied for direct analysis for cyclopropenoid fatty acids (CPEFAs) as methyl esters. No thermal alterations were indicated in CPEFA methyl esters on a Supelcowax IO or a DB-5 capillary column like other fatty acid methyl esters (FAMES), which obviated a second derivatization. GC conditions are described for a complete separation and quantitation of CPEFAs in cottonseed oils. CPEFAs of cottonseed oils from various refining steps were analyzed by the method. The reliability of the method was demonstrated with over 95% recoveries of CPEFA methyl esters diluted in corn oil FAMES at various levels as low as 0.017%.

Caracterização química do óleo da amêndoa de Sterculia striata St. Hil. et Naud

“…Os grupamentos ciclopropênicos são destruídos, com o aquecimento e o meio ácido, no processo de extração e transesterificação 10 . Podem ser também decompostos termicamente no injetor ou nas colunas polares do cromatógrafo a gás durante a análise.…”

“…Os efeitos biológicos destes compostos sobre animais têm sido objeto de várias investigações, incluindo atividades cocarcinogênica e carcinogênicas [8][9][10] . O ácido estercúlico é um inibidor da ∆ 9 -dessaturase, a qual converte o ácido esteárico em ácido oleico, sendo potencialmente nocivo para o homem uma vez que pode alterar a permeabilidade das membranas e inibir a reprodução 11 .…”

Determination of Nutritional and Cyclopropenoid Fatty Acids in Cottonseed by a Single GC Analysis

“…An alternate GC stationary phase, 5 % diphenyl 95 % dimethyl polysiloxane, was used to confirm the absence of C18:3n6. This stationary phase allows for better resolution of the CPFA from NFA, compared to PEG columns [7]. In addition to evaluating retention times, the relative proportions of the CPFA injected on each column were calculated by area % and found to be equivalent, indicating an absence of co-eluting peaks.…”

“…Currently, methods for CPFA utilize gas chromatography (GC). However, these methods are inherently different from those used for NFA, which employ acid catalyzed esterification, and often a different GC column stationary phase [7]. Using base esterification as a starting point [8], a method was developed that analyzes both CPFA and NFA in a single GC procedure.…”

In Situ Preparation of Fatty Acid Methyl Esters for Analysis of Fatty Acid Composition in Foods

“…conversion of 0-acyl lipids to FAME and do not usually form FAME from free fatty acids (Luddy et al, 1968;Glass, 1971). A base-catalyzed reaction is a useful alternative to acid-catalyzed reactions when a lipid sample contains acid-labile fatty acids such as cyclopropenoids, present in seed oils from the Malvales order, such as cottonseed oil (Park and Rhee, 1988;Gaydou et al, 1993). To effect solubilization of nonpolar lipids such as triacylglycerols in methanol, the predominant solvent in derivatization reagents, benzene is frequently added to the derivatization reaction mixture (Sukhija and Palmquist, 1988;Sattler et al, 1991;O'Keefe et al, 1994).…”