Patent ID: 8357542

Claim:
An atmospheric nitrate-ion measurement method comprising: a collection step of suctioning atmospheric air at a constant flow rate of at least 90 liters per hour through a filter to collect particulate matter from the suctioned air on the filter; an extraction step of i. contacting the filter with a solvent, of relative volume that is less than or equal to 1.1×10 −5 times the volume of air suctioned per hour by the suction part, to extract the particulate matter on the filter and dissolve the particulate matter into the solvent, ii. collecting the resultant solution, and iii. feeding the solution from said extraction step into a measuring means; a nitrate-ion measurement step of measuring the optical absorbance of the solution with the measuring means at predetermined wavelengths, to obtain characteristic absorbance spectra correlating to amount of nitrate ions in the solution; and a recording step of recording the measurement results obtained in said nitrate-ion measurement step.