Performance of an Aerodyne Aerosol Mass Spectrometer (AMS) during Intensive Campaigns in China in the Summer of 2006

An Aerodyne quadrupole aerosol mass spectrometer (AMS) was deployed in China in the summer of 2006. The measurements were made in the Pearl River Delta region in July 2006 (PRD campaign) and also in Beijing in August–September 2006 (CAREBEIJING campaign). The AMS successfully measured size-resolved chemical composition of submicron non-refractory aerosol (vaporized at 600°C in vacuum) with a time resolution of 10 min, although some quantification issues have been identified. We observed extremely large signals at m/z 39 ( 39 K + ) and 41 (41K + ), which significantly exceeded m/z 28 (N + 2 ) signals. We also found large signals of m/z 85 ( 85 Rb + ), 87 (87Rb + ), and 133 (Cs + ). Laboratory experiments suggest that the large enhancement of K + could have been due to the presence of K-containing particles in ambient air. The interferences of alkali metals at m/z 41, 85, 87, and 133 were significant and need to be corrected for better quantification of organic aerosol. The AMS measurements are compared wit...