Fig. 3. High performance liquid chromatography (HPLC)–mass spectrometry (MS) investigation of the 1:1 DIMBOA + atrazine reaction mixture: (A) base peak chromatogram (BPC) and (B–F) electrospray ionization (ESI) mass spectra corresponding to the labeled signals at retention time (t_r) 9.7, 13.7, 14.2, 16.7, and 19.1 min, respectively.