An accurate and reliable method for identification and quantification of fatty acids and trans fatty acids in food fats samples using gas chromatography

Abstract

A method for the separation, identification and further quantification of fatty acids (FAs) and trans fatty acids (TFAs) by gas chromatography (GC) using the combination of lipid extraction and derivatization with the base-catalysed method followed by trimethylsilyl-diazomethane (TMS-DM) was developed. The proposed method was found to allow sensitive and accurate determination of a wide range of different types of FAs, including TFA isomers. The method was validated on real samples of dietary fat from hydrogenated edible oils (margarine) and nine standard FAs as representatives of margarines. For this purpose, response linearity, limit of detection (LOD), limit of quantification (LOQ), precision and recovery (R%) were all determined. Based on the results obtained, R-values from all the samples were revealed to be close to 100%, repeatability RSD ranged between 0.89% and 2.34%, and reproducibility RSD values ranged between 1.46% and 3.72%. The applicability of this method was demonstrated in four margarine samples and it was compared with the method used as reference. In general, the results proved that the proposed method is suitable for the analysis of FAs since it has shown higher effectiveness in TFA analysis than the classic methods. Thus, it could be an effective tool for analysing dietary fats and oils in complex mixtures of food products for the monitoring of low levels of FAs and TFA, and the control of labelling authenticity.

Keywords

• Quantification
• Trans fatty acids
• Food fats
• Derivatization
• Margarine