| 1. |
- Löfgren, Lars, 1964, et al.
(författare)
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Butenes and butadiene in urban air
- 1992
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Ingår i: The science of the total environment. ; 116, s. 195-201
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
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| 3. |
- Löfgren, Lars, 1964
(författare)
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Determination of Volatile Hydrocarbons in Urban Air
- 1992
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the complex hydrocarbon mixture in urban air, the alkenes and arenes are of particular interest with respect to impact on health and environment. Knowledge of hydrocarbon concentrations in urban air is essential for the assessment and prevention of health hazards and photochemical oxidant formation. Hydrocarbons in urban air were sampled on specially made triple-layer adsorbent cartridges. Easily carried equipment was used for the sampling. After thermal desorption, the hydrocarbons were analyzed by gas chromatography. An aluminium oxide column effected the separation of C2-C6 alkenes. Detection was generally by flame ionization but optional photoionization detection was found to be advantageous for the selective detection of alkenes and alkadienes in the C3-C5 region. A recently introduced technique based on differential optical absorption spectroscopy (DOAS) was compared with the gas chromatographic method for the determination of benzene and toluene in air. Proportions and exposure levels of hazardous hydrocarbons were determined in urban air. Ethene, propene, 1,3-butadiene and benzene made up approximately 5, 2, 0.5 and 6 per cent by weight of non-methane hydrocarbons. The composition was different for cold-start and high-speed emissions. Among the four isomeric butenes, the 2-butenes were prominent in petrol vapour and methylpropene in exhaust. The composition of pentenes was similar in petrol vapour and petrol exhaust. Concentrations of butadiene, reflecting outdoor urban exposure, were in the range of 0.5-5 mg/m3. The exposure of commuters to 22 volatile aromatic hydrocarbons of petrol exhaust was 5-10 times higher in cars than in trains. Generally, urban roadside concentrations of hydrocarbons decreased more than 10-fold with increased distance from motor traffic.
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| 4. |
- Löfgren, Lars, 1964, et al.
(författare)
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Exposure of commuters to volatile aromatic hydrocarbons from petrol exhaust
- 1991
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Ingår i: The science of the total environment. ; 108, s. 225-233
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Tidskriftsartikel (refereegranskat)abstract
- Twenty-two volatile aromatic hydrocarbons were determined in the air of an automobile during commuting. Sampling was made on Tenax cartridges and laboratory determinations were carried out using thermal desorption combined with temperature-programmed capillary gas chromatography. Selected hydrocarbons representative of petrol exhaust were determined in the automobile and in an electric commuter train during eight parallel commuter trips. In the automobile, the concentrations of benzene were 35-70 micrograms/m3 and those of total aromatic hydrocarbons 200-400 micrograms/m3. The petrol exhaust levels were 5-10 times higher in the automobile than in the compartment of the commuter train.
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| 5. |
- Löfgren, Lars, 1964, et al.
(författare)
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Photoionization assessment of C3-C5 alkadienes and alkenes in urban air
- 1992
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Ingår i: Journal of Chromatography. ; 591, s. 358-361
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Tidskriftsartikel (refereegranskat)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.
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| 6. |
- Löfgren, Lars, 1964, et al.
(författare)
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Proportions of volatile hazardous hydrocarbons in vehicle-polluted urban air
- 1992
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Ingår i: Chemosphere. ; 24, s. 135-140
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Tidskriftsartikel (refereegranskat)abstract
- Hydrocarbons of particular toxicological interest were determined in Scandinavian urban air as their fraction of total hydrocarbons except methane. Samples were taken on triple-layer adsorbent cartridges and the C2-C8 hydrocarbons were analyzed by gas chromatography on an Al2O3/KCl column. The approximate ratios 10:4:1 were observed for ethene, propene and butadiene. The proportion of these combustion-derived alkenes was low for cold starts, and highest for fast traffic.
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| 7. |
- Löfgren, Lars, 1964, et al.
(författare)
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Selective assessment of C2-C6 alkenes in air by adsorption sampling and gas chromatography
- 1991
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Ingår i: Journal of environmental analytical chemistry. ; 45, s. 39-44
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Tidskriftsartikel (refereegranskat)abstract
- A system is described for the specific determination in air of ethene, propene, the four isomeric butenes, cyclopentene and the six isomeric pentenes. The butenes, pentenes and hexenes are well separated from the commonly occurring matrix of alkanes in much higher concentrations. Field samples were taken using easily carried equipment consisting of an air pump connected to an adsorbent cartridge. An advantageous combination of triple-layer adsorbents was found to be Tenax + Carbotrap + Carbosieve S-III. In the laboratory, the hydrocarbons were thermally desorbed into a cold trap. The trap was directly linked to the aluminium oxide PLOT column which effected the alkene separations.
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