Simple derivatization of aldehydes with D-cysteine and their determination in beverages by liquid chromatography-tandem mass spectrometry

We describe a simple derivatization method to determine aldehydes. This method is based on derivatization with D-cysteine and consecutive liquid chromatography-tandem mass spectrometry (LC-MS/MS). The optimum derivatization conditions of aldehydes with D-cysteine were 10 min at 50 degrees C and pH 7.0. The formed alkyl thiazolidine-4-carboxylic acid derivatives were directly injected in LC-MS/MS. In the established condition, the method was used to detect eight aldehydes in beverages. The limit of detection (LOD) and limit of quantification (LOQ) of the aldehydes were 0.2-1.9 mu g L-1 and 0.7-6.0 mu g L-1 and the relative standard deviation was less than 2.0% at concentrations of 0.1 mg L-1 and 1.0 mg L-1 with the exception of octanal. All the beverage samples had detectable levels of methanal (0.033-0.145 mg L-1), ethanal (0.085-2.12 mg L-1), propanal (ND to 0.250 mg L-1), butanal (ND to 0.003 mg L-1), pentanal (ND to 0.471 mg L-1), hexanal (ND to 0.805 mg L-1), heptanal (0.019-3.91 mg L-1) and octanal (0.029-0.118 mg L-1). Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.