Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Chemosphere. 2010 Apr;79(4):394-400. doi: 10.1016/j.chemosphere.2010.02.008. Epub 2010 Feb 21.
The heterogeneous ozonation of suspended malathion and chlorpyrifos particles are studied in real-time with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The pesticide particles with the diameter of hundreds of nanometers are generated by the homogeneous nucleation method using azelaic acid as nucleus. The reactions are carried out in an aerosol reaction chamber under ambient pressure (1 atm) and room temperature (298 K), respectively. The time-of-flight mass spectra of the solid-state ozonation products of malathion and chlorpyrifos are obtained. The assignments of the mass spectra reveal that the major ozonation products of malathion particles are s-(1,2-diethoxycarbonyl)ethyl-O,O-dimethylphosphorothioate (malaoxon), 2-mercapto-succinic acid diethylester, 1,2-dicarbethoxyethyl-dimethoxyphosphinyldisulfide and bis(1,2-bis-ethoxycarbonyl-ethyl)disulfide. The experimental results reveal that water vapor can enhance the formation of malaoxon, 2-mercapto-succinic acid diethylester and bis(1,2-bis-ethoxycarbonyl-ethyl)disulfide. In the case of chlorpyrifos, the sole ozonation product observed is 3,5,6-trichloro-2-pyridyl-diethylphosphate (chlorpyrifos oxon). The pathways of heterogeneous ozonation of malathion and chlorpyrifos particles are proposed. The atmospheric lifetimes of malathion and chlorpyrifos particles towards ozone reaction are estimated based on the time-dependent mass spectrometric signals obtained.
采用真空紫外光电离气溶胶飞行时间质谱仪（VUV-ATOFMS）实时研究了悬浮马拉硫磷和毒死蜱颗粒的多相臭氧化反应。使用壬二酸作为核，采用均相成核法生成直径数百纳米的农药颗粒。在气溶胶反应室中于环境压力（1 大气压）和室温（298 K）下进行反应。获得了马拉硫磷和毒死蜱固态臭氧化产物的飞行时间质谱。质谱的分配揭示了马拉硫磷颗粒的主要臭氧化产物是 s-(1,2-二乙氧羰基)乙基-O,O-二甲基硫代磷酸酯（马拉氧磷）、2-巯基琥珀酸二乙酯、1,2-二羰乙氧基乙基二甲氧膦二硫醚和双(1,2-双乙氧羰基乙基)二硫醚。实验结果表明水蒸气可以促进马拉氧磷、2-巯基琥珀酸二乙酯和双(1,2-双乙氧羰基乙基)二硫醚的形成。对于毒死蜱，观察到的唯一臭氧化产物是 3,5,6-三氯-2-吡啶基二乙基磷酸酯（毒死蜱氧磷）。提出了马拉硫磷和毒死蜱颗粒多相臭氧化的途径。基于获得的时变质谱信号，估计了马拉硫磷和毒死蜱颗粒与臭氧反应的大气寿命。
