Time-resolved monitoring of aromatic compounds in an experimental incinerator using an improved jet-resonance-enhanced multi-photon ionization systemJet-REMPI

REMPI (Resonance Enhanced Multi-Photon Ionization) mass spectrometry has a large potential for continuous in-line monitoring, for example, in incinera tion. Through the introduction of Jet-REMPI, a sensitivity enhancement of s everal orders of magnitude can be achieved and this gives access to an incr eased number of compounds that are relevant for thermal processes, but furt her improvements are needed to exploit this multicomponent capability fully within reasonable measurement times, in order to scan over all relevant or accessible components, a tunable laser is needed capable of covering a wid e wavelength range in a short time without the necessity of changing dyes o r other means of adjustment. This wide laser wavelength range is demonstrat ed by measurements of laboratory spectra of some compounds typically found as PICs (products of incomplete combustion) along with an NO spectrum as an example of monitoring in the far UV. Further successful tests of the new m onitor have been carried out in conjunction with an experimental incinerato r. A nearly perfect match was found between the wavelength dependent spectr a obtained with laboratory test gas mixtures and those in the incinerator f lue gas. This apparent absence of interferences is the most important resul t of the present paper. Measurements conducted in parallel using convention al methods indicate a Jet-REMPI detection limit for 1,2 dichlorobenzene in the sub-ppt range.