[Analysis of atmospheric pollutants with coupled gas chromatography-atomic absorption or thermodesorption-gas...

We have perfected a specific and original analytical method suitable for organic and inorganic compounds using sampled run-off water collected nearby a filling station. The dissolved lead species are volatilized by substituting the inorganic ligands with hydrogen, using sodium-borohydride in a suitable reaction medium (H2O2, KOH). The volatile lead hydrides are then trapped on a gas chromatographic column filled with Chromosorb W impregnated with 2% of OV 275 and immersed in liquid nitrogen. After desorption, the products are analysed by atomic absorption spectroscopy. We have carried out the analysis of aldehydes mixtures, sampled from a smog chamber. They are trapped, at room temperature, in a glass column filled with Tenax. These pollutants are then heated at 250 degrees C under a flow of nitrogen, and trapped again in a melted silica capillary column at -110 degrees C. This trapping being over, the column is drastically heated at 200 degrees C, which drives the products into the capillary column of a gas-chromatograph apparatus. This method has also enabled us to carry out a direct analysis of these pollutants sorbed on particles which have been placed into the glass column. this thermodesorption-gas chromatography system, coupled with a mass-spectrometry apparatus, allows us to identify and analyse most atmospheric pollutants.