2019 Volume 54 Issue 6 Pages 195-201
We developed a continuous measurement system of particulate organic nitrates (PONs) based on thermal dissociation followed by a cavity attenuated phase shift spectroscopy (TD-CAPS) technique. The PONs and BG lines were set in this system. For the PONs line, ambient air is introduced into an activated carbon denuder to remove the ambient O3, NO2 and gaseous organic nitrates. The air from the denuder is introduced into a heated quartz tube at 360℃ for thermal decomposition of the PONs to NO2, then the NO2 concentration is measured using a CAPS technique. For the BG line, ambient air is passed through a filter to remove particles including PONs before being introduced into the activated carbon denuder. The Concentrations of PONs are obtained by subtracting the NO2 concentrations measured by the BG line from those by the PONs line. An activated carbon fiber sheet is used in the activated carbon denuder. Characterization of the activated carbon denuder was performed and the optimized denuder has a breakthrough time of more than a half year and a transmission efficiency of more than 90% for PONs. Continuous observations of PONs were made using the TD-CAPS instrument at Osaka Prefecture University. This result demonstrates the performance of this instrument for PONs measurements.
