Gas-phase O3 reaction of dimethyl phthalate and diethylphthalate: a kinetic and product study

Phthalates are chemical species widely used as plasticisers that are known to be absorbed by living organisms and negatively affect their health. Phthalates have been detected mostly indoors. For example, they have been measured in the gas phase, as part of particulate matter and on different surfaces in the form of dust.^1-4 Although their presence in this kind of environments is well known and widely documented, there are scarce studies on their behaviour when they are in contact with tropospheric oxidants such as ozone (O₃) or hydroxyl radicals.^5-7

The aim of this work is to measure, for the first time, the kinetics of the gas-phase reaction of O₃ with two phthalates: dimethyl phthalate (DMP) and diethyl phthalate (DEP). In a smog chamber at room temperature and atmospheric pressure, decay rates of DMF or DEF are measured by a Proton Transfer-Time of Flight-Mass Spectrometer (PTR-ToF-MS), while the O₃ concentration is determined by Fourier Transform Infrared (FTIR) spectroscopy. Gas-phase products are also monitored by PTR-ToF-MS and secondary organic aerosol (SOA) formation is also evaluated by a Fast Mobility Particle Sizer. The impact on the indoor air quality of DMP and DEP will be discussed considering their atmospheric lifetime and the generated products.

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