Butenes and butadiene in urban air
Artikel i vetenskaplig tidskrift, 1992
Samples of urban air hydrocarbons were taken on specifically made adsorbent cartridges and analysed by gas chromatography after thermal desorption. The four isomeric butenes and 1,3-butadiene were favourably resolved and separated from the abundant alkanes on an aluminium oxide PLOT column. The concentrations of butadiene, reflecting outdoor urban exposure, were in the range of 0.5-5 micrograms/m3. An approximate 1:4 ratio was observed between butadiene and propene which both originate predominantly from vehicle exhaust. The four butenes made up approximately 50% of the propene concentration in exhaust-polluted air, with methylpropene greater than 1-butene greater than trans-2-butene greater than cis-2-butene. Petrol vapour contributed less than exhaust but about five times more to the 2-butenes than to methylpropene and 1-butene. The highest exposure levels of butadiene and butenes were consistently observed in the vicinity of exhaust pipes and petrol-fuelled vehicles.