Application of 2-(2,3-naphthalimino)ethyl trifluoromethanesulphonate as a pre-column derivatization reagent for high-performance liquid chromatography in the determination of 3-hydroxybutyrate in aqueous solution

Abstract

2-(2,3-Naphthalimino)ethyl trifluoromethanesulphonate (NE-OTf), as a pre-column derivatization reagent for high-performance liquid chromatography, has been tried for the determination of 3-hydroxybutyrate in aqueous solution. Thus far, NE-OTf has been inapplicable to short-chain carboxylic acids and an aqueous reaction system. 3-Hydroxybutyrate in aqueous solution reacted completely with an excess amount of NE-OTf in the presence of dimethyl sulfoxide, and N-ethyldiisopropylamine under a water-bath with sonic vibration setted at 45°C for 40 min. Under this condition, excess amounts of NE-OTf were also completely destroyed, and any chromatographic peaks due to by-products did not interfere with the determination of 3-hydroxybutyric acid ester derivative. The calibration curve of a 3-hydroxybutyrate standard solution was linear over the range of 0.02∼2.0 nmol for 10 μl injection, with a correlation coefficient of 0.9988. The detection limit (signal-to-noise ratio = 3) for 3-hydroxybutyrate was 2 pmol for 10 μl injection. By this method, NE-OTf was successfully applied to the determination of 3-hydroxybutyrate in aqueous solution.