Chemical composition and sources of amines in PM2.5 in an urban site of PRD, China

Atmospheric amines have attracted increasing attention due to their significant impact on new particle formation, particle hygroscopicity and particle optical properties. In this study, four low-molecule-weight amines were detected from PM_2.5 filter samples collected at an urban site of Pearl River Delta (PRD) region of China in 2018 autumn. During the campaign, the mass concentrations of ambient particulate methylamine (MA, CH₃NH₂), dimethylamine (DMA, (CH₃)₂NH), trimethylamine (TMA, (CH₃)₃N), and diethylamine (DEA, (C₂H₅)₂NH) were quantified at daily or 12-h resolution using an optimized Ion Chromatograph (IC) method. The total measured amine concentration was 297 ± 209 ng/m³, which can account for 0.76 ± 0.33% of PM_2.5 mass concentrations. The particulate amines in PRD urban area were dominated by MA (243 ± 179 ng/m³), accounting for over 80% of total amines, then followed by DMA (49 ± 30 ng/m³, 16.5%), TMA (4 ± 2 ng/m³) and DEA (1 ± 1 ng/m³). Based on the correlation analysis, MA and DMA mainly presented as nitrate and sulfate salts. We speculate the amines tend to react with gas-phase HNO₃ or particle-phase nitrate to form particulate amine salts via local process in Guangzhou. As the relative humidity (RH) increased, enhanced partitioning of amine towards the particle phase was observed. Using approach of multiple linear regression, 71% of the particulate amines in PRD urban site could be explained by acid-base process and the rest by primary emissions from combustion sources (29%).

Determination of atmospheric amines at Seoul, South Korea via gas chromatography/tandem mass spectrometry

Due to their important roles in salt-producing acid-base reactions, new particle formation (NPF), and as precursors in secondary organic aerosol (SOA) producing reactions, the atmospheric concentrations of particulate volatile amines (dimethylamine (DMA), ethylamine, diethylamine (DEA), propylamine, and butylamine) at Seoul were analyzed and evaluated. To quantify the presence of volatile amines in particulate matter with aerodynamic diameters less than or equal to a nominal 2.5 μm (PM_2.5), an efficient and rapid analytical method based on in-matrix ethyl chloroformate (ECF) derivatization followed by headspace solid-phase microextraction (HS-SPME) was developed and validated using gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) in the multiple reaction monitoring (MRM) mode. The annual mean concentration of the total 5 target amines was 5.56±2.76 ng/m³ and the seasonal difference was small. The concentrations of particulate amines measured in this study were lower than those observed in Zongludak, Turkey, Nanjing, China, and Jeju, Korea but slightly higher than that reported in Kobe, Japan. The concentrations of the nitrosamines (nitrosodimethylamine (NDMA) and nitrosodiethylamine (NDEA)), and of the nitramines (dimethylnitramine (DMN) and diethylnitramine (DEN)) measured along with those of the target amines were used in a simple linear regression analysis. It indicates the contribution of DMA to the formation of NDMA in all seasons (except the fall) and DEA to the formation of NDEA in the summer, while DMA and DEA did not significantly contribute to the formation of nitramines.