Heat-Refluxextraction (HRE) and GC/MS Analysis of Polycyclic Aromatic Hydrocarbons and Their Nitrted Derivatives Adsorbed on Diesel Combustion Engine Prticles

This study aims at the identification and quantitative determination of polycyclic aromatic hydrocarbons (PAHs) adsorbed on soot particles emitted by diesel engines, but also of their nitro derivatives "nitro-PAHs". The challenge is double: develop a Heat-reflux extraction (HRE) technique to selectively and quantitatively extract the targeted pollutants adsorbed on soot, and to analyze them at trace amounts. Extraction results using dichloromethane showed a modest improvement in the extraction of volatile PAHs (more than 80%) and heavy PAHs (10 to 20%). Among the other solvents tested, pyridine proved to be the best extractant, with 50% extraction of the heaviest PAHs. Combined with diethylamine, the extraction efficiency of heavy PAHs reached 90%, which proves the ability of the pyridine-diethylamine mixture to extract quantitatively all PAHs, alkanes and nitro-PAHs. Moreover, pyridine associated with 1% acetic acid allowed the quantitative extraction of heavy nitro-PAHs, which were only partially desorbed with previous solvents. In comparison, when extracting real soot directly from a diesel engine test bench, very high amounts of linear alkanes from C14 to C32 were obtained, but few PAHs : naphthalene, biphenyl, phenanthrene, anthracene and fluorine (0.31-4.84 µg.g-1) and nitrated derivatives: 1-nitronaphtalene, 2-nitrofluorene and 1-nitropyrene (0.97-1.78 µg.g-1).