Extraction and Characterization of Surfactants from Atmospheric Aerosols (original) (raw)

2017, Journal of Visualized Experiments

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in the Earth's atmosphere, a central process in meteorology, hydrology, and for the climate system. But because specific extraction and characterization of these compounds have been lacking for decades, very little is known on their identity, properties, mode of action and origins, thus preventing the full understanding of cloud formation and its potential links with the Earth's ecosystems. In this paper we present recently developed methods for 1) the targeted extraction of all the surfactants from atmospheric aerosol samples and for the determination of 2) their absolute concentrations in the aerosol phase and 3) their static surface tension curves in water, including their Critical Micelle Concentration (CMC). These methods have been validated with 9 references surfactants, including anionic, cationic and non-ionic ones. Examples of results are presented for surfactants found in fine aerosol particles (diameter <1 μm) collected at a coastal site in Croatia and suggestions for future improvements and other characterizations than those presented are discussed. Video Link The video component of this article can be found at https://www.jove.com/video/55622/ Further improvements and other types of characterizations, that could be used in complement to those presented, will be discussed. Recent applications of these methods have already shown how such analyses can improve the understanding of the role of surfactants in cloud formation, by evidencing this role itself, 3 determining the surfactant concentrations in atmospheric aerosols 3,4,5,6 and mode of action in cloud droplet formation, 3,6 evidencing their biogenic origin, 3,4,7 and explaining their lack of observation by classical instruments.