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Organic Chemistry - Carbon Compounds
• Carbon - C, atomic number 6, molecular weight 12
• Electron configuration: 1s22s22p2
• Tetravalent – 4 single bonds (sp3); 2 double bonds (sp2) one triple (sp) plus one single bond
Secondary Organic Aerosol (SOA)• SOA processes are studied
in photoreactors • European photoreactor
(EUPHORE) in Valencia, Spain, is one of the largest (200 m3) and the best-equipped outdoor simulation chamber in the world
• We are studying atmospheric transformation of diesel emissions under the influence of sunlight, ozone, hydroxyl radicals that occur during transport in ambient air
VOC, SVOC and PM
• Vapor pressure ranges:
VOC: > 102 Pa (10-1 Torr)
SVOC: 102 and 10-6 Pa; (10-1 and 10-8 Torr)
PM: < 10-6 Pa (10-8 Torr)
Hazardous Air Pollutants (HAPs)
• Full list – 188 compounds, most of them organics
• The short list – 33 air toxics, most prevalent in urban area
• No ambient standards – regulation of emissions from sources
_ announced in September 2006: PM2.5 annual 15 µg/m3 and 24-hr 35 µg/m3; PM10 annual only
• Climate change• Visibility problem (Haze Rule)
Average Ambient PM2.5 Composition in Urban Areas
EPA STN network
Average PM10-2.5, PM2.5, and PM0.1 composition at EPA “supersite” in Los Angeles, CA, 10/2001 to 9/2002
US EPA OAQPS PM Staff Paper, June 2005
Organic Aerosol • Organic aerosols are solid or liquid particles
suspended in the atmosphere containing organic carbon
• Semi-volatile organic compounds (SVOC) - distributed between gas and particle phases –reversibly condensable
• Particle associated organics – complex mixture, incorporated into/onto particles; includes condensed SVOC and non-volatile organic compounds
Measurement Methods
• Collection of VOC and aerosol samples followed by off-site laboratory analyses
• VOC collection: stainless steel SUMMA canisters
• PM and SVOC: Filters followed by solid adsorbents
Operational Definitions of SVOC and PM - Associated OC
Filter-Adsorbent (FA) AF
AFDDenuder-Filter-Adsorbent (DFA)
AEElectrostatic precipitator (EA)
Filter-Filter-Adsorbent (FFA)
F1F A
Analysis - Chromatography
• Chromatography is a separation method that relies on differences in partitioning behavior between a flowing mobile phase and a stationary phase to separate the components in a mixture.
Gas Chromatography (GC)
• Examples of "hyphenated techniques" include gas and liquid chromatography with mass spectrometry (GC-MS and LC-MS), Fourier-transform infrared spectroscopy (GC-FTIR), and photo diode-array UV-VIS absorption spectroscopy (HPLC-UV-VIS).
• HPLC - liquid chromatography that utilizes high-pressure pumps to increase the efficiency of the separation