Ion-trap tandem mass spectrometry for the determination of heterocyclic amines in food

Heterocyclic amines (HAs) are mutagenic compounds to which humans are regularly exposed through diet. Due to the high complexity of the sample matrix and the low level of concentration of HAs, sensitive and selective analytical methodologies are required. Here we describe a methodology based on liquid chromatography–atmospheric pressure chemical ionisation tandem mass spectrometry using an ion-trap to analyse HAs. The collision-induced dissociation parameters for tandem ion-trap spectrometric analysis of these mutagenic compounds were optimised, and the full scan MS–MS spectra were used for unequivocal identification of the analytes. For aminoimidazoazaarenes, the most abundant ions were derived from the loss of a methyl group and the breaking of the aminoimidazole moiety, while for carbolines the major product ions arose from the loss of ammonia and HCN. Moreover, the performance of the LC–atmospheric pressure chemical ionisation MS–MS method was evaluated. The good precision (RSD lower than 11%) and the low detection limits achieved (10–60 pg injected) allow the determination of HAs at low part-per-billion level (0.4–5.0 ng g−1) in a lyophilised meat extract.