Sampling and trace determination of fine particulate semi-volatile nitrosamines and related nitrogenous compounds in the atmosphere.

摘要

Nitrosamines and related nitrogenous compounds are mainly secondary pollutants formed by photo-chemical reactions in the atmosphere. Because of their semi-volatility, these compounds usually distribute both in gas and fine particulate phases. Furthermore, these organic compounds are suspected of being human carcinogens and mutagens. Accurate determination of these toxic organic compounds is critical to elucidating the chemical and biological mechanisms underlying the association between exposure to fine particles and observed health effects. In an effort to improve the understanding of the association between fine particulate pollution and mortality, a routine method has been developed for the selective and trace determination of nitrosamines and related nitrogenous compounds in the atmosphere.;First, a group-selective method has been developed for the determination of total nitrosamines and organic nitrites in atmospheric samples. The method can accurately determine concentrations as low as 0.8 pmol nitrites and nitrosamines in 2 muL sample extracts without any significant interference from water, nitrate or other compounds. Second, a high-volume sampling system (PC-BOSS) has been developed and field evaluated specifically for the determination of particulate semi-volatile compounds based on Harvard particle concentrator and BOSS diffusion denuder techniques. To simplify the sampling procedures, an extractable carbon filter has been validated for the simultaneous determination of both organic and inorganic semi-volatile species in the atmosphere. Finally, using the developed sampling and analytical techniques, fine particulate nitrosamines, nitramines, organic nitrates and nitrites have been determined in two field sampling programs. The experimental results have been explained according to the atmospheric formation mechanisms of these organic compounds and other related factors including gas phase air pollutants, meteorological parameters and solar insolation.