Development and laboratory characterization of passive sampling method for amines in ambient air.
Résumé
Atmospheric amines are basic organic compounds that originate from both natural and anthropogenic sources. They are recognized to have a significant role in the formation of fine particulate matter (PM) in the atmosphere by acid-base reactions with atmospheric acids like sulfuric or nitric acids (H2SO4; HNO3) and also to play a role in the growth of particles, either directly by dissolution of amines in partially liquefied aerosols, or indirectly, by oxidation, oligomerization, or nucleation processes (Ge et al., 2011; Xiao et al., 2021). Depending on the proximity with the sources, amines are found at varying concentrations in the atmosphere ranging from a few pptv to several hundred of ppbv and there are only a few methods for identifying and characterizing these amines in ambient air and there is no passive method well adapted to determine the spatial distribution of these compounds.
In consequence, this study examined the performances of a chemical radial diffusive sampler (RAD168 from Radiello®) for the weekly measurement of 7 amines mostly found in the atmosphere (methylamine; ethylamine; dimethylamine; diethylamine; trimethylamine; dimethylethylamine; butylamine). A test program was carried in an annular exposure chamber with the aim of validating the passive sampling method. It allowed the estimation of all the parameters of the method for each compound (calibration, analytical precision, desorption efficiency, uptake rate in standard conditions, detection limit and stability of sample before and after exposure) and also the examination of the influence of the presence of ammonia on the sampling rate. The results of this evaluation demonstrated that the method has turned out to be suitable for the seven amines tested. In standard conditions (i.e. temperature = 20°C; relative humidity = 50%) and depending upon the compounds, the experimental values of uptake rate for one-week exposure are between 503 mL.min-1 (dimethylamine) and 3287 mL.min-1 (methylamine) which give relatively low detection limits in air between 0.2 and 7.1 ng.m-3 (0.1 to 3.9 pptv) without any interference of ammonia even at 10-folder concentration.
References:
Ge X. et al. (2011). Atmospheric amines - Part I. A review. Atmospheric Environment, 45(3), 524–546.
Xiao M. et al. (2021). The driving factors of new particle formation and growth in the polluted boundary layer. Atmospheric Chemistry and Physics, 21, 14275-14291.