Fate and Distribution of Trace Organics Using On-line Mass Spectrometry

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*This research program is centred on the novel application of emerging mass spectrometry (MS) techniques to address important questions in environmental chemistry. MS discriminates between molecules based on their mass-to-charge ratio and is a powerful analytical technique with inherent sensitivity and selectivity advantages. When techniques designed to follow unique mass fragmentation pathways are employed, MS instruments have even greater molecular resolving power. When a semi-permeable membrane is used as an interface between the sample and the mass spectrometer, it allows the concentration of analytes to be continuously monitored. Until recently, membrane introduction MS has been limited to relatively volatile organic compounds. Coupling membrane inlets employing a solvent acceptor phase to atmospheric pressure ionization has extended the technique to a wide range of biologically and environmentally relevant compounds. This proposal describes the use of MS to directly measure molecular determinants of environmental and human health. In addition to foundational contributions to the field of environmental chemistry the research described here has broader application in contaminant fate modeling, environmental engineering, and eco-toxicology.****Real-time MS techniques provide unique opportunities for the investigation of mass transport phenomena, the direct observation of changes in chemical concentration in dynamic systems, and the ability to map chemical information over geographic scales during mobile operations. The time-resolved MS signals generated as analytes permeate through a membrane, provide a direct probe of intrinsic molecular and material properties. This will be used to predict environmentally relevant distribution coefficients and to characterize the permeability of new materials. Furthermore, since membrane introduction MS measures the ‘free' chemical concentration in solution, it can employed for the direct observation of partitioning and binding behaviour. The use of in-situ reaction monitoring strategies will be utilized to provide kinetic information for physical and chemical processes at environmentally relevant conditions (trace concentrations, multiple components, heterogeneous). When operated continuously on a mobile platform, mass spectrometers provide chemical information with unprecedented data density that is resolved in both time and space. In addition to geographically referenced concentrations, which can be used for regional scale emission inventories and exposure studies, this proposal describes the use of chemometrics to provide compositional information from non-targeted full scan mass spectra. This work contributes directly to the study of fate, distribution, and transport of trace contaminants in the environment and has implications to risk assessment, source apportionment and emergency response.**** **