Instrumental Innovations for Membrane Introduction Mass Spectrometry

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The identification and measurement of trace levels of molecules in real world samples is the end goal of analytical chemistry. Unfortunately, trace level measurements made in complicated, real-world samples (municipal waste water, blood, urine, tissue fluids, etc.) can be confounded by the other, major components of the samples (interferents), adversely affecting successful results. Direct determinations are desirable, because they are simple, and can reduce the risk of altering the results through contamination or dilution. The successful measurement of key determinants of environmental and human health in real samples (pesticides, hormones, drugs, metabolites, etc.) is challenging because many current analyses require sample cleanup, concentration and other preparation steps, adding both time and cost, as well as the risk of potential contamination or dilution of the samples. My research program is aimed at developing new approaches for the direct, online, ‘real-time’ measurement of trace level molecules (analytes) in complex, real samples, with important applications in environmental, bioanalytical (medical, pharmaceutical) and material sciences. The basis for this work is to use polymer (or other) membranes as a direct bridge between complex air or water based samples and mass spectrometers (MS), which are used for the subsequent identification and measurement of trace level analytes. The technique, called membrane introduction mass spectrometry (MIMS), is direct and continuous, eliminating sample pretreatment steps: quantitative, molecularly specific measurements are possible. Analytes that transfer from the sample across the membrane do so as a mixture, where they are converted into ions, and analyzed by the MS. Because analyte transfer from a sample is continuous across the membrane, MIMS can also determine concentration changes over time, providing key information (e.g. real-time air quality measurements, industrial waste stream monitoring, point-of-care medical diagnostics, etc.) that can be missed when analyzing single samples. MIMS' selectivity for analytes arises from the membrane choice, the ion generation approach and the mass measurement steps. My research will explore the development of improved, miniaturized membrane-sample interfaces, enabling rapid, low-cost, selective, direct measurements for small samples, investigate selective and sensitive ion generation approaches and their subsequent MS detection, and the evolutionary development of compact, portable MIMS based systems, that in the long term will enable direct, real-time measurements when and where they are needed, providing high precision results out-of-the-lab, crucial in events such as critical incidents (environmental spills) as well as in providing timely medical diagnostics, enabling better quality health care, improving the quality of life for all Canadians.