On-line resonance-enhanced multiphoton ionization time-of-flight laser mass spectrometry for combined multi-component-pattern analysis and target-compound monitoring: Non-chlorinated aromatics and chlorobenzene in flue gases of combustion processes

Resonance-enhanced multiphoton ionization (REMPI) allows different degrees of optical ionization selectivity. The selectivity achievable with the REMPI-method is compared with that of other ionization methods for on-line mass spectrometry. "Semi-selective" REMPI with effusive molecular beam inlet allows group selective ionization of mono- and polycyclic aromatic compounds and their methylated derivatives (REMPI at 266 nm). The patterns of the above mentioned aromatic compounds in flue gases can be used for characterization of industrial combustion processes. In this work, a novel approach of "semi-selective" REMPI for measurement of the patterns of mono- and polycyclic aromatic compounds, with additional simultaneous target compound monitoring, is presented. By using REMPI at 269.8 nm monochloro benzene, which is an important indicator for the toxicity of the flue gas, can be monitored, together with the other aromatics. On-line recorded REMPI mass spectra from the flue gas of an industrial hazardous waste incineration plant are presented. The applications of REMPI on-line monitoring at incineration plants are discussed.