| Ambient measurements of trace gas phase species in the Earth's troposphere continue to present an interesting analytical challenge. Instruments must have sufficient sensitivity to monitor low concentrations without compromising the specificity necessary to distinguish the analyte of interest from a complex matrix. A chemical ionization mass spectrometer (CIMS) has been designed and constructed to satisfy these criteria.;Upon validation, the CIMS will assist in the elucidation of the complex chemistry in the troposphere resulting from the influence of urban pollution and marine environment. The CIMS is currently configured to operate in the negative ion mode and employs I- as the reagent ion for detection of nitryl chloride (ClNO2). Gas phase ClNO2 is thought to be a reservoir species for tropospheric chlorine atoms and was accordingly chosen as the first target analyte. The design and construction of the CIMS, the validation plan and potential future directions will be discussed in detail. |
