Simultaneous Sampling of NO, NO 2 , HONO and HNO 3 in the Atmosphere by a Filter-Pack Method

A simultaneous sampling method for gaseous nitric oxide (NO), nitrogen dioxide (NO 2 ), nitrous acid (HONO) and nitric acid (HNO 3 ) was developed by a filter-pack sampling method to measure these concentrations at low cost in areas where monitoring stations are not available or at multiple locations. HONO and HNO 3 gases were collected with a conventional filter-pack method. NO 2 was collected with a guaiacol-impregnated filter at a flow rate of 0.3 dm 3 min −1 . NO was collected using guaiacol by oxidizing it to NO 2 with potassium permanganate at a 0.3 dm 3 min −1 flow rate. The optimum concentration of KMnO 4 in the immersion solution for the impregnated filter was 0.16 mol dm −3 (in 0.51 mol dm −3 H 2 SO 4 ). The concentrations of NO and NO 2 measured by the filter-pack method were in good agreement with those measured by the chemiluminescence method. It was calculated that 60 ppb NO could be oxidized to NO 2 with the KMnO 4 -impregnated filter for 183 hours at a 0.3 dm 3 min −1 flow rate. This is enough time for sampling in a real environment. This method was applied to measure NO, NO 2 , HONO and HNO 3 in the atmosphere at three points around Osaka, Japan.