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Measurement of Acrylonitrile in Ambient Air

Measurement of Acrylonitrile in Ambient Air. AMTAC April 12, 2011 John Bricarello California Air Resources Board. Requirements. Need to find alternate to 910 sampler Cannot pass air through an instrument prior to capturing the acrylonitrile

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Measurement of Acrylonitrile in Ambient Air

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  1. Measurement of Acrylonitrile in Ambient Air AMTAC April 12, 2011 John Bricarello California Air Resources Board

  2. Requirements • Need to find alternate to 910 sampler • Cannot pass air through an instrument prior to capturing the acrylonitrile • Must be more sensitive than current method (MLD066 RL = 0.3 ppb) • Must be able to deploy a sampler without too much disruption to field personnel

  3. Where we left off May 2009 • Select appropriate sorbent material • Finalize instrumental method • Select sampler for sorbent tubes • Establish sampling protocol with low flow pump • Test designed methodology and generate results • Move final methodology to field

  4. Solid SorbentCarboxen 1000 • Advantages • Good reproducibility for standards • Low trap desorption temperature, few artifacts • Can be used more than 200 times • Handles low sampling flows over 24 hour period • Detection ‘on tube’ <0.05ng • Disadvantages • Advertised as hydrophobic, it still retains a significant amount of water • Designed for C2 – C5 molecules it retains up to C10 organics both polar and non-polar

  5. Instrumentation

  6. Sampling and Problems • Startup • Battery operated personal pump equipped with four tube holder • One sample tube, three spiked tubes • Battery operated – did not last 24 hours • Fair recovery with inside air, very poor recovery in outside air • Water in air interfered with retention of acrylonitrile • Theorized that pressure drop across sorbent tube led to water condensation

  7. Sampler Version 1 Quad Manifold Tube Heater Variac Heater Controller Pump Tubes Clips Heater

  8. Sampler Version 2 Figure 1 Figure 2 Figure 3 Figure 5 Figure 4

  9. MLD’s Roof Top Monitoring Platform Results Average Median Maximum Minimum Result, ppt 2.4 2.5 8.2 0.7 Recovery, % 66 70 102 21 Correl. Coeff. 0.9973 0.9988 1.000 0.9816 Average of all >300ppt (60 in Million cancer risk) canister results = 590ppt

  10. Typical Acrylonitrile MS Output Typical TIC of Sample containing methanol Extracted Ion Chromatogram of Standards, Sample & Spikes

  11. Acrolein • Testing • Added acrolein to acrylonitrile standards • Issues • Stability of acrolein in canisters compared to acrylonitrile • Alternate methodology • The follow slide shows acrylonitrile - acrolein comparison

  12. Acrolein Results MLD Roof ACN Acrolein ppt ppt Avg. 5.5 223 Med. 4.6 182 Max. 22.5 978 Min. 1.1 65 Rec.avg 78% 57% All Monitoring Sites Avg. 590 680 n= 2197 3894 n: > 300ppt results 4560 total measurements

  13. Observations and Other Anecdotal Information • Passivated Carboxen 1000 • Fiberglass epoxy enclosure caused interferences • PVC led to elevated acrylonitrile levels • Sampler influences result • Higher results on calm days than windy days • Tubes need to be heated all the time

  14. What is Coming • Develop Sampler version 3 • Deploy sampler to selected sites • Finalize analytical SOP for acrylonitrile and possibly acrolein • Compare site data • Determine shipping, sampling and receiving logistics • Deploy to all network sites if feasible

  15. Contact John Bricarello, APS California Air Resources Board Monitoring and Laboratory Division jbricare@arb.ca.gov (916) 327-2336

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