2.3. Preparation of reducing mini column packed with copperized cadmi um
A copperized cadmium column was prepared as follows: powdered cadmium (Wako Pure Chem., 60-80 mesh) was copperized according to the procedure of the Japanese Industrial Standard (JIS K-0 10 1- 1991), and the copperized cadmium obtained was packed in a silica tubing (0.53 mm i.d. x 10cm).
2.4. Procedure for the collection of NO2 from air and the measurement of NO/ and NO3-
Air samples were pumped through separatory funnels (260 ml) for 2 min in order to sufficiently exchange air in the separatory funnels for the sample. Then, 2ml of an absorption solution was added into each separatory funnel, and the separatory funnels were shaken vigorously for 4 min. After standing for 1 min, nitrate andlor nitrite ion in the absorbing solutions were measured by the proposed pFIA.