Simultaneous identification of different classes of hydrocarbons and determination of nitro-polycyclic aromatic hydrocarbons by means of particle beam liquid chromatography mass spectrometry

LC-MS with a particle beam interface was used to separate and identify aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and their nitrated derivatives (nitro-PAHs). In particular, the behaviour of nitro-PAHs and of two nitrated biphenyls was checked in terms of instrumental response. A normal-phase chromatographic system was used, with a silica column and heptane-tetrahydrofuran as mobile phase. Electron impact and positive- and negative-ion chemical ionization (NICI) modes were used; for nitro-PAHs, the best results were obtained under NICI conditions. In the flow-injection mode, detection limits as low as pg levels were obtained for 9-nitroanthracene, 3-nitro-9-fluorenone, 1-nitropyrene, 1,8-dinitronaphthalene, 2,7-dinitrofluorene and 2,7-dinitro-9-fluorenone, whereas the low-molecular-mass 1- and 2-nitronaphthalene were not detected even at mu g levels; using the analytical column, a detection limit five times higher was determined for 1-nitropyrene. For most of the nitro-PAHs considered, the dependences of the intensities on the amounts injected were found to be linear in a range of more than two orders of magnitude.