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 gasesof combustion processes

Resonance-enhanced multiphoton ionization (REMPI) allows different degrees of optical ionization selectivity. The selectivity achievable with the REMP I-method is compared with that of other ionization methods for on-line mass spectrometry, "Semi-selective" REMPI with effusive molecular beam inlet al lows group selective ionization of mono- and polycyclic aromatic compounds and their methylated derivatives (REMPI at 266 mm), The patterns of the abo ve mentioned aromatic compounds in flue gases can be used for characterizat ion of industrial combustion processes. In this work, a novel approach of " semi-selective" REMPI for measurement of the patterns of mono- and polycycl ic aromatic compounds, with additional simultaneous target compound monitor ing, 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 prese nted, The applications of REMPI on-line monitoring at incineration plants a re discussed.