Determination of carboxylic acids by high-performance liquid chromatography with 2-(2,3-anthracenedicarboximido)ethyl trifluoromethanesulfonate as a highly sensitive fluorescent labelling reagent

Abstract

2-(2,3-Anthracenedicarboximido)ethyl trifluoromethanesulfonate (AE-OTf) is a highly sensitive fluorescent labelling reagent for carboxylic acids for use in liquid chromatography. The labelling reaction of carboxylic acids with AE-OTf was completed within 10 min at room temperature in acetonitrile in the presence of tetraethylammonium carbonate as a base. The 2-(2,3-anthracenedicarboximido)ethyl esters of 18 kinds of fatty acids including polyunsaturated fatty acids were separated from each other on an ODS column with an isocratic solvent system within 30 min. The relative standard deviations of their peak areas were within 2%(n= 8, 1.4–3.3 pmol on-column). Their relative peak areas were almost 1.0 and their detection limits were 0.8–2.7 fmol (signal-to-noise ratio = 3). These fatty acids were successfully determined at least over the range 20 fmol-6 pmol (correlation coefficient r >0.999 for all fatty acids tested).