title: Gas/particle partitioning of 2-methyltetrols and levoglucosan at an urban site in Denver.
abstract: In this study, a medium volume sampler incorporating quartz fiber filters (QFFs) and a polyurethane foam (PUF)/XAD/PUF sandwich (PXP) was used to collect 2-methyltetrols (isoprene tracer) and levoglucosan (biomass burning tracer) in gaseous and particle (PM2.5) phases. The measured gas/particle (G/P) partitioning coefficients (Kp,OMm) of 2-methyltetrols and levoglucosan were calculated and compared to their predicted G/P partitioning coefficients (Kp,OMt) based on an absorptive partitioning theory. The breakthrough experiments showed that gas-phase 2-methyltetrols and levoglucosan could be collected using the PXP or PUF adsorbent alone, with low breakthrough; however, the recoveries of levoglucosan in PXP samples were lower than 70% (average of 51.9–63.3%). The concentration ratios of 2-methyltetrols and levoglucosan in the gas phase to those in the particle phase were often close to or higher than unity in summer, indicating that these polar species are semi-volatile and their G/P partitioning should be considered when applying particle-phase data for source apportionment. The Kp,OMm values of 2-methyltetrols had small variability in summer Denver, which was ascribed to large variations in concentrations of particulate organic matter (5.14 ± 3.29 μg m–3) and small changes in ambient temperature (21.8 ± 4.05 °C). The regression between log Kp,OMm and log Kp,OMt suggested that the absorptive G/P partitioning theory could reasonably predict the measured G/P partitioning of levoglucosan in ambient samples.
authors: Department of Mechanical Engineering, College of Engineering and Applied Science, University of Colorado , Boulder, Colorado 80309, United States.
authors: Mingjie
authors: M
authors: Xie
authors: Michael P
authors: MP
authors: Hannigan
authors: Kelley C
authors: KC
authors: Barsanti
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D002947:Cities; D003120:Colorado; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D005374:Filtration; D005947:Glucose / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D052638:Particulate Matter / Q000032:analysis / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D011791:Quartz; D012621:Seasons; D055549:Volatile Organic Compounds / Q000032:analysis / Q000737:chemistry
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D011140:Polyurethanes; D055549:Volatile Organic Compounds; D011791:Quartz; C014989:1,6-anhydro-beta-glucopyranose; D005947:Glucose