Volatile organic compounds (VOCs) are a broad category of complex volatile organic chemicals, including carcinogenic substances such as benzene and neurotoxic compounds such as toluene. In this study, we have established analytical methods to measure the carbon and hydrogen stable isotope ratios of benzene and toluene found in automobile exhaust and the general environment. Using these methods, we investigate the environmental behavior of these compounds.

In particular, benzene and toluene undergo photochemical reactions and gradually degrade in the atmosphere. We are also studying the changes in their isotope ratios that occur during these photochemical processes.

• New Hiroto Kawashima* (2022), Stable Carbon Isotope Ratio of Volatile Organic Compounds in Air Using Solid-Phase Microextraction Coupled with Chromatography, Combustion, and Isotope Ratio Mass Spectrometry, Chromatographia, vol.85, pp.871-881
• Hiroto Kawashima* (2015), The fractionation factors of hydrogen stable isotopes for VOCs, Procedia Earth and Planetary Science, vol.13, pp.185-188
• 川島洋人*（2014），同 位体比の環境科学への適用－第2講　安定同位体比による発生源解析－，大気環境学会誌，vol.49, pp.A47-A57
• Hiroto Kawashima*, Mai Murakami(2014), Measurement of the stable carbon isotope ratio of atmospheric volatile organic compounds using chromatography, combustion, and isotope ratio mass spectrometry coupled with thermal desorption, Atmospheric Environment, vol.89, pp.140-147
• Nami Kikuchi, Hiroto Kawashima* (2013), Hydrogen isotope analysis of benzene and toluene emitted from vehicles, Atmospheric Environment, vol.72, pp.151-158