In this paper, a direct immersion solid‐phase microextraction procedure for the simultaneous analyses of four primary riot control agents: 2‐chloroacetophenone, o‐chlorobenzylidene malonitrile, dibenz(b,f)‐1,4‐oxazepine, and oleoresin capsicum at μg/L concentration from environmental water was developed. Several parameters that influence the extraction effectiveness were investigated, including fiber type, extraction temperature, extraction time, starring rate, and salinity. Under the recommended conditions, the optimized method had reasonable linearity and accuracy. The average recovery of this method ranged from 84 to 108.1%. The limit of detection for all the analytes ranged from 0.2 to 3 μg/L and the limit of quantification ranged from 1 to 10 μg/L, respectively. A relative standard deviation from 3.0 to 4.3% can be achieved depending on the compounds. The procedure was applied to analyze all the four riot control agents simultaneously in several environmental samples.

The widespread surface of the air-water interface plays a crucial role in the partitioning processes between the atmosphere and the hydrosphere. As one of the prime CWAs (Chemical Warfare Agents) abandoned by Japanese, the unfound 2-Chloroacetophenone posed a severe threat to the Chinese people. In this study, the interface partition constant of 2-Chloroacetophenone was obtained by measuring the mass uptake vapor on different environmental water films with various thicknesses. The surface tension, dissolved organic matter, and salinity of the environmental samples were analyzed. The partition constant of 2-Chloroacetophenone in pure water, river water and sea water samples at 288 K were 1182.2 ± 49.9, 1606.6 ± 101.3 and 408.9 ± 18.3, respectively. Surface adsorption is the predominant mechanism. The results also indicate that the adsorption partitioning ability of 2-Chloroacetophenone at the air/water interface was negatively correlated with surface tension. 2-Chloroacetophenone is more likely to adsorb at the gas/water interface with lower surface tension.

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The fate of atmospheric volatile organic compounds (VOCs) strongly depends on the partitioning processes on the surface of aerosols, which are coated with a thin water film. However, the behavior of VOCs in the aqueous film of aerosols is difficult to measure. In this work, the interfacial partition constant of cyclohexanone was determined using a novel flow-tube reactor. A thin, aqueous film placed in the reactor was exposed to cyclohexanone gas. The subsequent partitioning was measured using chromatography techniques. The quality control tests were first conducted to ensure the accuracy of the adsorption experiments. The cyclohexanone concentration was then plotted as a function of film thickness to obtain the partitioning constants. As the thickness of the water film decreased, the aqueous concentration of cyclohexanone increased, indicating that surface adsorption played a dominant role in the uptake of cyclohexanone. According to the temperature dependence of the interfacial partition constant, the solvation enthalpy and entropy of cyclohexanone were obtained. The results of this study would help to elucidate the effect of atmospheric water film on the gas–aerosol partitioning of VOCs, and thus can help to better understand the fate of VOCs in the atmosphere.

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