Determination of trans-fatty acids in food samples based on the precolumn fluorescence derivatization by high performance liquid chromatography.

Abstract

Trans-fatty acids are unsaturated fatty acids that are considered to have health risks. 1,3,5,7-Tetramethyl-8-butyrethylenediamine-difluoroboradiaza-s-indacene is a highly sensitive fluorescent labeling reagent for carboxylic acids developed by our lab. In this study, using this precolumn fluorescent derivatization reagent, a rapid and accurate high-performance liquid chromatography with fluorescence detection method was developed for the determination of two trans-fatty acids in food samples. Under the optimized derivative conditions, two trans-fatty acids were tagged with the fluorescent labeling reagent in the presence of 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide at 25°C for 30min. Then, the baseline separation of trans- and cis-fatty acids and their saturated fatty acid with similar structures was achieved with less interference using a reversed-phased C18 column with isocratic elution in 14min. With fluorescence detection at λex /λem =490 /510nm, the linear range of the TFAs was 1.0-200nM with low detection limits in the range of 0.1-0.2nM (signal-to-noise ratio=3). In addition, the proposed approach was successfully applied for the detection of trans-fatty acids in food samples, and the recoveries using this method ranged from 96.02 to 109.22% with low relative standard deviations of 1.2-4.3% (n=6).