Ion/molecule reactions of o-carborane(12) and a method for identifying overlapped isotopic distributions in complex mass spectra

A high resolution Fourier transform ion cyclotron resonance mass spectrometer was used to investigate gas phase ion/molecule reactions of o-carborane(12) (o-C₂B₁₀H₁₂). The reaction of o-carborane(12) neutrals and cations produced oligomeric carborane species. Extensive hydrogen losses and H₂O/CH₃OH adducts were also observed and these resulted in complex mass spectra containing overlapped isotopic distributions. For a cell pressure of 6.0 x 10^-9 mbar and for reaction delays from 50 ms to 30 s, some 73 species were identified in the resultant mass spectra, and their reaction kinetics were explored using a simplified, six step reaction mechanism. The analysis of these complex mass spectra was simplified by MACLOOMIS, an interactive program based on pattern recognition techniques originally developed for the analysis of high resolution vibration-rotation spectra. When adapted to mass spectra, MACLOOMIS enabled the rapid identification of overlapped isotopic distributions, and this approach may prove useful for a wide range of mass spectrometry studies. (C) 2000 Elsevier Science B.V.