Evaluation of poly(90% biscyanopropyl/10% cyanopropylphenyl siloxane) capillary columns for the gas chromatographic quantification of trans fatty acids in non-hydrogenated vegetable oils

Abstract

Current gas chromatographic (GC) methods for the analysis of fatty acids (FA) were optimized primarily for the quantification of the trans 18:1 FAs (18:1 tFAs) produced during the partial hydrogenation of fats and oils. Recent regulatory action regarding the application of partial hydrogenation in the processing of edible fats and oils may reshape the FA composition of these products. The higher content in 18:3 tFAs compared to 18:1 tFAs of most refined non-hydrogenated vegetable oils (RNHVO), and the challenge in their quantification applying current methods, suggest the need for new methodologies. This manuscript describes a simple GC method for the analysis of FAs in RNHVOs utilizing a 100m (0.25mm I.D.) capillary column coated with poly(90% biscyanopropyl/10% cyanopropylphenyl siloxane) (90% BCS). The optimization of the chromatographic conditions and the detection of co-eluting compounds were carried out by applying comprehensive two dimensional gas chromatography with online reduction (GC-OR×GC). Results showed that 90% BCS capillary columns operated at the elution temperature of 162°C provide the separation of the 18:1, 18:2 and 18:3 tFAs, contained in RNHVOs, from other components. A minor constituent of Canola oil, 16:3n-3, partially co-eluted with trans-18:1 FAMEs. This simple GC method showed the ability to measure trans-fat in RNHVOs at the level of 0.5g/100g, providing comparable quantitative results to the more complex GC×GC methodology.