Comparison of dimethylformamide dialkylacetal derivatization reagents for the analysis of heterocyclic amines in meat extracts by gas chromatography-mass spectrometry

A simple and selective methodology for the analysis of heterocyclic amines (HAs) in a meat extract by gas chromatography-mass spectrometry (GC-MS) is proposed. A comparative study of several HAs derivatization procedures based on the formation of Schiff bases using N,N-dimethylformamide dialkylacetals reagents was performed. Optimization of the reaction conditions was carried out, such as reagent volume (2 μl to derivatize 1 ng of HAs) temperature (100 °C) and time (10 min). After that, the GC-MS working parameters for the analysis of HAs derivatives were also studied in order to achieve the best chromatographic separation with the maximum sensitivity. Among the derivatization reagents, N,N-dimethylformamide di-tert-butylacetal (DMF-DtBA) was selected because it provided the best yield in the derivatization process, and consequently the best sensitivity in the GC-MS method. Quality parameters such as limits of detection and repeatability were established using a meat extract sample. A complete validation of the methodology was achieved using a laboratory reference material previously analyzed in a European interlaboratory exercise.