A study of BTEX-ratios in the urban area of Munich/Germany using rapid gas chromatography.

During October 1993 rapid in-situ quasi-continuous GC/FID measurements of aromatic compounds (BTEX) were carried out at two urban sites in Munich/Germany. A cycle time of 10 min allowed determination of shorttime BTEX emission variations and their impact on selected BTEX ratios. The ethylbenzene/ Sigmam/p-xylene ratio showed the smallest variations even in case of rapid changes in the BTEX-mixture. It appeared to be almost independent of the emission strength. Therefore this ratio is suggested to be primarily dependent on photochemical processes in urban environments. It provides an indicator for the impact of anthropogenically related hydrocarbon chemistry leading to the formation of secondary pollutants.