Airmodus A70 Chemical Ionization Inlet uses nitrate ions to charge the sample to an atmospheric pressure time of flight mass spectrometers (API-TOF; Tofwerk AG and Aerodyne Research). The charging is done in soft manner with virtually no wall contact in order to prevent fragmentation and losses. This allows detection of single molecular species up to clusters of molecules with really low noise level. For example sulfuric acid molecules can be detected in sub-ppt levels and neutral clusters of sulfuric acid and dimethyl amine can be detected up to cluster with tens of sulfuric acid molecules in them. This allows measurement of clustering and nucleation processes from molecular scale to nanometer scale. The A70 Ci-inlet is designed for continuous use and is tested both in laboratory and field measurements.