Department of Environmental Science and Engineering, Fudan University, 220 Handan Road, Shanghai, 200433, China.
Environ Sci Technol. 2010 Jun 15;44(12):4441-6. doi: 10.1021/es1001117.
High molecular weight (M(w)) species were observed at substantial intensities in the positive-ion mass spectra in urban Shanghai aerosols collected from a single-particle time-of-flight mass spectrometer (in the m/z range 250-500) during three separate periods over 2007-2009. These species correlate well with the CN(-) mass signal, suggesting that C-N bonds are prevalent and that the observed high-M(w) species are potentially nitrogen-containing organic salts. Anti-correlation with the ambient O(3) concentration suggests that photochemical oxidants are not involved directly in the formation of these species. The Mannich reaction, among amines (or ammonia), formaldehyde, and carbonyls with an adjacent, acidic proton, is proposed as a plausible pathway leading to these organic salts. Although the high-M(w) species observed in the single-particle mass spectra appear to be nitrogen-containing organics, further chemical confirmation is desired to verify if the proposed Mannich reaction can explain the formation of these high-M(w) species in regions where ammonia, amines, and carbonyls are prevalent.
在 2007 年至 2009 年期间的三个不同时间段内，使用单颗粒飞行时间质谱仪（m/z 范围为 250-500）在上海市区气溶胶的正离子质谱中观察到高分子量（M（w））物质，其强度很大。这些物质与 CN（-）质量信号很好地相关，表明 C-N 键很普遍，并且观察到的高分子量物质可能是含氮有机盐。与环境 O（3）浓度呈负相关表明，光化学氧化剂没有直接参与这些物质的形成。拟议的曼尼希反应是一种合理的途径，其中胺（或氨）、甲醛和羰基与相邻的酸性质子反应，生成这些有机盐。尽管单颗粒质谱中观察到的高分子量物质似乎是含氮有机物，但需要进一步的化学确证来验证所提出的曼尼希反应是否可以解释在氨、胺和羰基普遍存在的地区形成这些高分子量物质的原因。
