Measurement of phase-distributed nitrophenols in Rome ambient air

Atmospheric nitrophenols (NPs) were determined both in the gas and particle phases by combining the annular denuder sampling technique with GC-MS analysis. The phase distribution of six mono-NPs identified in air sampled in downtown Rome was assessed. 4-NP, 3-methyl-4-NP and 2,6-dimethyl-4-NP were found for more than 75% in the particle phase, whilst 2-NP, 4-methyl-2-NP and 5-methyl-2-NP predominated in the gas phase. Concentration levels lower than 20 ng m−3 were observed for all NPs, among which 4-NP (17.8 ± 5.6 ng m−3) and 2-NP (10.4 ± 4.2 ng m−3) were the most abundant congeners in the two phases, respectively.