CHROMATOGRAPHY-MASS SPECTROMETRY OF TRINITROTOLUENE ISOMERS IN THE NEGATIVE IONIZATION MODE UNDER RESONANCE ELECTRON CAPTURE

For trinitrotoluene isomers by gas chromatography-mass spectrometry (GC-MS), the processes of chromatographic separation and formation of negative ion (NI) mass spectra in the mode of resonant electron capture, implemented by a minimal technical modification of the domestic serial GC-MS complex “Chromatech-Crystal”, were investigated and compared with the basic mode of positive ions (PI) under electron ionization. The chromatographic retention time of the isomers was found to increase in direct proportion to the dipole moment of the molecules, illustrating the significance of intermolecular dipole interactions between polar molecules of the analyte and the stationary phase. It is shown that the chromatograms of full current OI, which are recorded at fast constant scanning of ionizing electron energy in the low-energy range of 0-10 eV, well reflect the component composition of the analyzed sample, and the integral mass spectra of OI are characteristic and selective to isomers, being complementary in informativeness to the standard mass spectra of PI. This is due to the predominance of nitro-nitrite rearrangements and simple C-NO2bond breaking at negative ionization over H-shift reactions, which dominate in the formation of PIs from TNT isomers.