Reductive amination of aldehyde 2,4-dinitrophenylhydrazones using cyanoborohydride for determination of selected carbonyl compounds in Port wines, table wines, and wine spirits

Abstract

Carbonyl compounds are mainly analysed by HPLC with ultraviolet detection after reaction with DNPH, yielding carbonyl-hydrazones. The presence of geometrical isomers whose relative abundance is dependent on the reaction condition introduces analytical errors and increases the complexity of the chromatograms. In this work, a simple, fast, and robust method for determining pyruvic acid, acetaldehyde, and α-ketobutyric acid in Port wines, dry table wines, and wine spirits by reductive amination of aldehyde 2,4-dinitrophenylhydrazones using cyanoborohydride followed by HPLC-DAD was developed, optimised and validated. The developed method was simple and showed good performance in several parameters such as linearity (0.025-200 mg/L), detection limits (0.0043-0.0097 mg/L), quantification (0.014-0.032 mg/L), precision (1.1-4.2 %) and accuracy (99.02 %). The method was applied to five different wine matrices, White, Tawny, and Ruby Port wines, white and red table wines, and wine spirits. The quantification of these carbonyl compounds simultaneously was achieved in Port wines for the first time.

Keywords: 2,4-Dinitrophenylhydrazine; Carbonyl compounds; Cyanoborohydride; HPLC-DAD; Reductive amination; Wine.