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Analytical and Environmental Chemistry Research

Our group’s research focuses on the identification of emerging environmental contaminants using a combination of state-of-the-art mass spectrometry, multidimensional separation techniques and computational chemistry. We study how these pollutants impact the environment and human health, and work collaboratively with partners in industry and government to guide the development of safer chemicals and effective regulatory interventions.

Environmental mass spectrometry

An atmospheric pressure ion source: the reaction vessel in which we do our chemistry!

  Tens of thousands of chemical substances, consisting of millions of individual chemical compounds, have been introduced to the global market. These chemicals are essential to modern society, but concerns have been raised that some may persist in the environment for many years and bioaccumulate in humans and wildlife.

  Attempts to detect and regulate these chemicals have been limited to only a handful of substances. Mass spectrometry is the most widely used technique for the identification of environmental contaminants. In such experiments, the identity of a pollutant molecule must be deduced from the behaviour of its corresponding ion. Our group studies this ion chemistry and devises novel approaches to selectively ionize and detect toxic chemicals. Our lab is equipped with state-of-the-art mass spectrometry instrumentation that can simultaneously detect tens of thousands of compounds present in complex environmental and biological samples. We develop computational and informetric approaches to analyze mass spectrometry data with the ultimate goal of identifying emerging contaminants.

Multidimensional separations

The contour plot obtained from a GCxGC experiment is like a topographic map where the peaks and mountains correspond to chemical compounds.

  Comprehensive two-dimensional gas chromatography (GCxGC) is an elegant technique that can separate complex mixtures prior to mass spectrometry detection.  As sample molecules pass through a tubular gas chromatography (GC) column, their progress is impeded by their affinity or natural attraction to the walls of the column (stationary phase) and separation occurs due to differences in affinities between compounds. In GCxGC, separation occurs during two stages of GC, which is enabled by a device called a modulator that serves to trap molecules eluting from the primary column and re-injecting them into the secondary column (2nd dimension).

  Our group is studying the benefits of combining GCxGC with atmospheric pressure ionization sources that will allow us to perform faster separations, exploit structure-diagnostic ion-molecule reactions for structure elucidation, and coupling GCxGC to advanced tandem mass spectrometry techniques, including ion mobility. In ion mobility experiments, collisions with gas molecules impede the mobility of the ions, resulting in separation according to their shape, which is characterized as an ion’s collisional cross section (CCS). While the mass of a molecule can be used to deduce the composition of its constituent elements, its shape is directly related to its structure, environmental behaviour, and biological function. Our group is working on how to use CCS measurements to discover undocumented pollutants, and potential environmental impacts, without prior knowledge of their occurrence or structure.

Exposomics

Chemical exposures are complex and poorly characterized. Exposure can occur during one's occupation. It can also occur during the course of everyday life, through diet and inhalation of indoor dust.

  The “exposome” represents all environmental exposures during the course of an individual’s or organism's lifetime. While environmental exposures are widely acknowledged to cause chronic disease, such as cancer, many of these exposures remain poorly characterized.

  Our group employs two fundamental strategies to study the exposome: The “bottom-up” approach involves measuring sources of exposure, including water, air, diet and other sources of outdoor and indoor pollution. The top-down strategy involves biological monitoring of exposed individuals and organisms that offer a more complete and accurate view of an individual’s exposures and their associated risks.

  We collaborate with clinician scientists, chemical biophysicists, computational chemists, epidemiologists, and experts in public health, to identify novel contaminants that are associated with adverse health outcomes at all stages of life. Identification of emerging pollutants is a crucial step towards establishing guidelines to limit exposure, and to prevent health outcomes that result from pollution.