ac035390x_si_001.pdf (19.7 kB)
Real-Time, On-Line Characterization of Diesel Generator Air Toxic Emissions by Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry
journal contribution
posted on 2004-05-01, 00:00 authored by Lukas Oudejans, Abderrahmane Touati, Brian K. GullettThe laser-based resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS)
technique has been applied to the exhaust gas stream of
a diesel generator to measure, in real time, concentration
levels of aromatic air toxics. Volatile organic compounds,
as well as several polycyclic aromatic hydrocarbons were
detected in the concentration range of 10−200 ppb in the
steady-state diesel generator exhaust. The results were
verified and compared with conventional extractive sampling and analytical techniques using gas chromatography/mass spectrometry (GC/MS). The high isomer selectivity of the REMPI-TOFMS instrument provided data
for individual xylene isomers that are otherwise (partially)
coeluting in standard GC/MS analyses. Good agreement
was observed between results for volatile and semivolatile
organic compounds obtained with REMPI-TOFMS and
conventional extractive sampling. Transient events, such
as cold start-ups of the diesel generator, resulted in sharp
(less than 15 s) peak emissions that were, for benzene,
up to a factor of 90 higher than the predominately
constant concentrations observed during steady-state
operation; warm restarts resulted in lower peak concentrations by a factor of 2.5. These fast transient emissions
are only detectable using a real-time approach (1-s
resolution) as demonstrated here using REMPI-TOFMS.