Liquid chromatography-mass spectrometry method for the determination of aldehydes derivatized by the Hantzsch reaction.

A liquid chromatography-mass spectrometry method for the determination of aliphatic aldehydes after derivatization with acetylacetone or dimedone by means of the Hantzsch reaction is presented. Two molecules of a beta-diketone, one molecule of ammonia and an aliphatic aldehyde cyclisate under formation of colored and fluorescent reaction products. Atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) in the positive mode are suitable to ionize the formed dihydropyridine and decahydroacridine derivatives under protonation of their basic secondary amine functionality. The method has been used to identify the oxidation product of the formaldehyde derivatives as side product. The acetaldehyde derivative, presumably formed in the reaction of residual acetaldehyde in the acetic acid or acetate reagents, is mainly responsible for the increasing fluorescence background of the reagent solutions.