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.