title: Near-real-time combustion monitoring for PCDD/PCDF indicators by GC-REMPI-TOFMS.
abstract: The boiler exit flue gas of a municipal waste combustor was sampled to evaluate an online monitoring system for chlorobenzene congeners as indicators of polychlorinated dibenzodioxin and dibenzofuran (PCDD/PCDF) concentrations. Continuous measurements of chlorobenzene congeners using gas chromatography coupled to a resonance-enhanced multiphoton ionization - time-of-flight mass spectrometry (GC-REMPI-TOFMS) system were compared over 5-min periods with conventional sampling methods for PCDD/PCDF. Three pairs of values were taken every hour over a period of three days to characterize the combustor's response to transient operating conditions (shutdowns and startups). Isolation of specific chlorobenzene congeners from other same-mass compounds was accomplished by using a GC column separator ahead of the REMPI-TOFMS. The 50-fold variation of PCDD/PCDF concentration was paralleled by similar changes in monitored compounds of 1,4-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3-trichlorobenzene, and 1,2,4,5-tetrachlorobenzene. A correlation of R = 0.85 and 0.89 was established between 40 pairs of simultaneous 5-min GC-REMPI-TOFMS measurements of 1,2,4-trichlorobenzene and 5 min conventional sampling and analysis for the TEQ and Total measures of PCDD/PCDF, respectively. The GC-REMPI-TOFMS system can be used to provide frequent measures of correlative PCDD/PCDF concentration thereby allowing for an understanding of measures to minimize PCDD/PCDF formation and develop operational feedback to limit emissions.
authors.affiliation: U.S. Environmental Protection Agency, Office of Research and Development (E305-01) Research Triangle Park, North Carolina 27711, United States. Gullett.brian@epa.gov
authors.forename: Brian K
authors.initials: BK
authors.lastname: Gullett
authors.forename: Lukas
authors.initials: L
authors.lastname: Oudejans
authors.forename: Dennis
authors.initials: D
authors.lastname: Tabor
authors.forename: Abderrahmane
authors.initials: A
authors.lastname: Touati
authors.forename: Shawn
authors.initials: S
authors.lastname: Ryan
mesh_terms: D001572:Benzofurans / Q000737:chemistry*; D000072338:Dibenzofurans, Polychlorinated; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000737:chemistry; D018531:Spacecraft; D013997:Time Factors; D014867:Water / Q000737:chemistry* / Q000592:standards*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D000072317:Polychlorinated Dibenzodioxins; D014874:Water Pollutants, Chemical; D014867:Water