Nontargeted detection and identification of (aromatic) amines in environmental samples based on diagnostic derivatization and LC-high resolution mass spectrometry.

The presence of aromatic amines in the environment has been in the focus of research, as many of these compounds are known or suspected mutagens and carcinogens. To facilitate the detection of aromatic amines in complex environmental samples by LC-high resolution mass spectrometry, an on-line-post-column and a pre-column derivatization method to label (in an ideal case) all aromatic amines was evaluated by applying different derivatization reagents. 4-Fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) was found to be the most promising labeling reagent due to its high reactivity with both primary and secondary amines and its low signal in positive mode electrospray ionization (ESI+). Post-column on-line derivatization did not result in sufficient signal intensities of derivatives. With pre-column derivatization most of the selected aromatic amines resulted in a derivative that shows common fragments of diagnostic value. The selectivity of NBD-F was studied in depth with a data set of 220 compounds with different functional groups showing that also aliphatic amines and some thiols yield a derivative. The developed method was successfully applied to wastewater effluent samples and several derivatives were confirmed by diagnostic neutral losses.