Proposal of the sampling methods for ionic compounds using non-equilibrium surface adsorption based on the new principle: Surface adsorption of ionic compounds under an applied electric field in indoor environments-the second -

The purpose of this study is to investigate whether it is possible to determine the fraction of ionized volatile organic compounds (VOCs) using the non-equilibrium surface adsorption onto an aluminum (Al) witness surface under various electric fields. The new principle was proposed to sample the ionized compounds effectively. As test compounds, low-molecular-weight cyclo-dimethyl-siloxanes(LMCSs) were selected. The authors attempted to sample ionized VOC molecules (especially high molecular weight ones) using the witness plate under an applied electric field. For the first step of this study exposure experiment was conducted to characterize the surface adsorption onto the witness plate and to determine the suitable exposure time for the non-equilibrium surface adsorption. For the main experiment to investigate the possibility of the ionized VOC sampling, the chamber experiments were conducted under a voltage with different polarities to the witness plate and the exposure of the witness plate to test VOC vapor including ionized species generated by a corona-discharge ionizer. This obtained results showed that there were significant differences in the adsorbed amount of test VOCs between the inverse polarity, same polarity and the neutral. Consequently, these results demonstrated that the possibility to determine the ionized fraction of high-molecular-weight VOCs in indoor environment where the ionizer operates.