Analysis of nitrogen-containing polycyclic aromatic compounds(N-PACs) in airborne particles emitted by petroleum asphalt mixing plants

Nitrogen-containing polycyclic aromatic compounds (N-PACs) are of increasing concern due to their enhanced toxicological relevance compared to their parent neutral PACs. In this study, airborne PM10 and asphalt binder samples were investigated in two asphalt mixing plants to evaluate the presence, distribution, and potential sources of N-PACs in an occupational setting associated with asphalt production. Particulate matter was collected at distinct locations, including the drum dryer and slat conveyor, to assess spatial variability, while asphalt binder produced at the same facilities was analyzed to explore potential links between raw materials and emitted particles. Quantitative analysis was performed by RP-HPLC–UV/DAD, with compound identities qualitatively confirmed by UHPLC–APPI–MS/MS. 1-Nitronaphtalene and 1-Nitropyrene were detected in PM10, whereas only 1-Nitronaphtalene was observed in the asphalt matrix under the analytical conditions applied. Spatial analysis revealed higher 1-nitropyrene concentrations near the slat conveyor, suggesting that process-related handling of heated asphalt mixtures may favor its formation and/or partitioning into airborne particles. Also, 1-Nitropyrene presence only in raw asphalt material suggests that it may be formed during heating of raw asphalt or in the gas phase by nitration.