Mass spectrometric characterization of Q1, a C9H3Cl7N2 contaminant in environmental samples

Q1, a heptachloro component of unknown structure and origin, was recently i dentified as a major organochlorine contaminant in samples from Africa and the Antarctic, Gas chromatography in combination with low resolution mass s pectrometry (LRMS) was applied to establish a molecular weight of m/z 384 i ncluding seven chlorine atoms. Three possible molecular formulae (C11H7Cl7, C10H3Cl7O, and C9H3Cl7N2) were proposed which could not be distinguished b y LRMS. In this presentation the molecular composition of Q1 was studied us ing gas chromatography in combination with high resolution electron impact ionization mass spectrometry. With the option of further heteroatoms (P, S, N, O, F, and Br), 17 molecular formulae were obtained for the molecular we ight of 384 u, In the selected ion monitoring (SIM) mode, performed with a resolution of 16,000, highest response was found at 383.812 or C9H3Cl7N2. 1 1 fragment ions detected in the low resolution full scan mass spectrum of Q 1 were also investigated in the high resolution SIM mode. In every case, th e nitrogen-variant showed highest abundance while the other 16 structural v ariants could be definitely excluded. These investigations revealed that th e molecular formula of Q1 is C9H3Cl7N2. No stable component with this molec ular formula has ever been reported in the literature, to our knowledge. Co pyright (C) 1999 John Wiley & Sons, Ltd.