Miniature Chemical Ionization Mass Spectrometer for Measuring Tropospheric Ammonia

Southwest Sciences proposes to develop an automated, fast, and compact instrument to measure tropospheric ammonia from light aircraft. Ammonia plays important roles in aerosol particle chemistry, and particle characteristics are critical in understanding climate change and air quality. Existing ammonia instruments are either too large or measure too slowly for use on light aircraft. The unique application of chemical ionization mass spectrometry (CIMS) to a state-of-the-art, miniature mass spectrometer offers the advantages of high sensitivity, small size, and low power consumption (< 200 W). Phase I will investigate the feasibility of detecting ammonia by a CIMS miniature mass spectrometer. At the end of Phase II, a small (30 x 30 x 30 cm) instrument will measure ammonia every 1-10 s with a detection limit of 20 parts per trillion. The proposed technology could also be used to measure other aerosol species such as nitric acid or sulfuric acid.