微粒子中の窒素の連続測定器の開発

抄録

An automated instrument which is capable of analyzing elemental nitrogen in particulate matters in real time is developed. Nitrogen compounds in particles (mainly nitrates) are introduced to a flame chimney so as to convert them into nitrogen monoxide with hydrogen-helium mixed gas. Then, nitrogen monoxide is oxidized into nitrogen dioxide by ozone supplied from an ozonizer. The resultant nitrogen dioxide in the excited state emits light and the concentration of elemental nitrogen is determined by using a Nitrogen Chemiluminescence Detector (NCD) . The calibration curve obtained using 0.23 to 2.3 ppm ammonia gas showed clear linearity. The performance and applicability of this method for the aerosol measurement are also evaluated with ammonium nitrate aerosols generated by a spray drying method. The measured concentrations of ammonium nitrate is compared with those measured by ion chromatograph. As a result, this method is applicable to monitor the nitrate particles though the concentration detected by this method is one-third of those detected by the ion chromatograph.