Photoionization assessment of C3-C5 alkadienes and alkenes in urban air

Abstract

Hydrocarbons from samples of traffic-polluted urban air were separated by gas chromatography on an aluminium oxide column and assessed simultaneously by photoionization detection (PID) and flame ionization detection (FID) after effluent splitting. The 10.2 eV photoionization detector selectively detects alkadienes and alkenes but not alkanes and alkynes in the C3-C5 region. The maximum PID/FID response ratio for alkadienes and alkenes is also obtained in this region. The analytical system as a whole is particularly favourable for the C3-C5 alkenes. Analytical data are given for propadiene, 1,3-butadiene, propene, butenes and pentenes.

Isomerization of β-Hydroxyalkoxy Radicals Formed from the OH Radical-Initiated Reactions of C4−C8 1-Alkenes

“…Table 1 clearly shows, as also evident from Figure 1, that the formation of dihydroxycarbonyls increases markedly with increasing carbon number of the 1-alkene and that decomposition of the β-hydroxyalkoxy radicals formed from the 1-butene and 1-pentene reactions dominates while isomerization of the β-hydroxyalkoxy radicals formed from the 1-heptene and 1-octene reactions dominates. This observed increase in importance of β-hydroxyalkoxy radical isomerization reaction in going from 1-butene to 1-octene is expected, since for the 1-butene reaction only the CH 3 (4,20). The formation of dihydroxycarbonyls from the gC 5 1-alkenes and the subsequent atmospheric fate of these dihydroxycarbonyls must now be taken into account.…”

“…The alkenes present in ambient air ( − ) originate from both anthropogenic and biogenic sources. In the troposphere, alkenes react with OH radicals, NO 3 radicals, and O 3 (), with the daytime OH radical reaction often dominating as their removal process ( , ).…”

Products of the Gas-Phase Reactions of 1,3-Butadiene with OH and NO3 Radicals

“…1,3-Butadiene [CH2dCHCHdCH2] is listed under Title III of the Clean Air Act Amendments of 1990 as a hazardous air pollutant (1) and is also on California's list of toxic air contaminants (2). 1,3-Butadiene is emitted into the atmosphere from a number of sources including vehicle exhaust (3)(4)(5)(6)(7)(8)(9)(10) and tobacco smoke (3,11,12) and has been measured in the troposphere at various locations (3,(13)(14)(15)(16)(17)(18)(19). In the troposphere, 1,3-butadiene can undergo reaction with OH radicals, NO3 radicals, O3, and Cl atoms (20).…”