Investigation of the use of resonance-enhanced multiphoton ionization spectroscopy and time-of-flight mass spectrometry (REMPI/TOFMS) for the continuous monitoring of stack gas emissions from hazardous waste incinerators will be carried out. In this program, the potential of the REMPI/TOFMS method for repetitive on-line monitoring of numerous species chosen from a list of currently identified surrogates will be investigated; the effort will combine detailed spectroscopic measurements of fundamental importance in understanding molecular structures with measurements of detection limits and selectivities needed for practical application of the technique. The apparatus to be used is a prototype of a potential portable sampling and detection system envisioned for on-line real-time monitoring at an incineration facility. Particular emphasis will be placed on one- and two-color REMPI spectroscopic studies of chlorinated polycyclic aromatics; analyses of the vibronic spectral signatures of these species will be carried out. Since formation and destruction of congeners of the chlorinated dibenzodioxins and dibenzofurans are expected to follow siminar pathways, spectroscopy of the less toxic, more abundant mono- and di-chlorinated species will receive high priority. Due to the importance of chlorinatef congeners of phenol as precursors to the formation of PCDDs and PCDFs, studies of detection limits and sensitivities for mono- and di-chlorinated phenols will also be carried out. Selectivity and detection limit measurements for two-color R2PI of biphenyl, p-dichlorobiphenyl, phenylphenol(4-hydroxybiphenyl), chloro-phenylphenon, phenanthrene, anthracene, and pyrene will also be made. Finally, studies of REMPI spectroscopy of dibenzo-p-dioxin, dibenzofuran, and several of their mono- and di-chlorinated congeners will be carried out. The spectral sensitivity of REMPI, realizable with jet-cooling of the sample, eliminates the need for time-consuming capillary column sample separation of conventional GC/MS analysis procedures which are considered to be impractical for use in continuous emission monitoring of incinerator effluents. It is anticipated that the potential of REMPI/TOFMS for real-time on-line repetitive monitoring of trace concentrations of wide classes of chlorinated organics, including polycyclic aromatic compounds, may help address current public health concerns and produce more effective and simplified licensing procedures for incinerators.
