Detection of Nitrooxypolyols in Secondary Organic Aerosol |Formed from the Photooxidation of Conjugated dienes under High- NOx Conditions Kei Sato, Atmospheric Environment, 42 (2008) 6851–6861

6-m 3,Teflon-coated, stainless steel laboratory smog chamber 2 ppmv of Isoprene NO concentrations were ranged from 0.2, 0.5 and 1 ppmv Particles collected on filters and solvent extracted Filters cut in small pieces and sonicated in 3ml of methanol for 40 min

 Analysis was by HPLC MS (Shimadzu LC–MS QP-8000a )  negative-ion mode ESI probe at 3.5 kV.

What if NO is very low; the primary reaction is with HO 2 Jenkin et al, 1997 Atmos. Envir., Pitts and Pitts, 186 RO 2. + HO 2.  ROOH + O 2 ROOH  carbonyl +H 2 O +O 2 and ROOH  alcohol + O 3 (dark O3) does the R group matter??? rate constants range: 5.2x R is CH 3 7.7x R is C 2 H 5 1.5x larger

What are the reactions of RO 2 (self reactions)? RO 2. + RO 2.  2RO.+O 2  ROH+RCHO + O 2  ROOR+ O 2 (SMALL) generally the larger the R group the slower the reaction Atkinson recommends 2.5x10 -13, 5x and 2x for primary, secondary and tertiary RO 2(s)

Is there data on the branching of 2RO vs. ROH+RCHO?? RO 2. + RO 2.  2RO.+O 2  ROH+RCHO + O 2  ROOR+ O 2 (SMALL) See Jenkin, et. al,1997, and Pitts and Pitts, Table 6.6, p 187 2RO.ROH+RCHO CH 3 OO CH3H7OO

High NOx RO 2 + NO  RO + NO 2 RO 2 + NO  RONO 2 Low NOx RO 2 + HO 2  ROOH + O 2 RO 2 + ROCH2O 2  ROH + O2 ROCHO  RO  R=O +HO 2

Low NOx

Formation of secondary organic particle phase compounds from isoprene gas-phase oxidation products: An aerosolchamber and field study: Alaf Bo¨ge, Yunkun Miao, Antje Plewka, Hartmut Herrmann, Atmos. Environ. Inpress, 2008) An overall yield of just 0.01–0.09% was estimated for methyl tetrol formation How much methyl tetrols forms?

What did Alaf Boge and Hartmut Herrmann do ? 9 m 3 chamber Added isoprene + H 2 O 2 Dimethyl tetrol + H 2 O 2 Isoprene epoxide + H 2 O 2

How do we write particle phase reactions for isoprene? Low NOx Isoprene + OH  IsoRO 2 IsoRO 2 + ? 

High NOx How much organic nitrate formation should we assume??

Isoprene in the presence of NOx produces nitric acid, 2-methylglyceric acid, 2-methyltetrols and nitrooxypolyols as the major products in SOA samples. The concentrations of the nitrooxypolyol products decreased three days after the extraction, whereas the concentrations of nitric acid and 2- methyltetrols increased.

These results suggest that the nitrooxypolyols produced by the diene oxidation in the presence of NOx contribute toward the SOA formation and that they can be decomposed into polyols and nitric acid in the aqueous solution. It was concluded that the direct formation of 2-methyltetrol by gas-phase diene oxidation is suppressed in the presence of NOx.

October 15, 2008 Run Log Purpose: Isoprene + O3 vs isoprene + NOx with VMU particle instrument to look at differences in particle phase and look for tetrols.. Injected Isoprene (117  l) into South or 1 ppmC (Sato article had ~2ppmV) Chamber conditions: vented from 18:00 to 22:37 pm gate valves. At 22:37 chamber gate valves were closed; exhaust blower off; compressor on, clean air generator on.

Chamber Background