Advanced Separation and Detection Methods for Supercritical Fluid Chromatography

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Our work aims to replace organic solvents with environmentally cleaner alternatives, which is a major concern in analytical chemistry and beyond. Many analytical labs coping with growing hazardous waste and slow sample throughput are switching to supercritical CO2 as a mobile phase, due to its low cost, green nature, and remarkable properties. For instance, in supercritical fluid chromatography (SFC), it yields faster separations than liquid chromatography and can analyze heavier compounds than gas chromatography. However, supercritical CO2 is non-polar and requires a polar organic modifier like methanol to be added for it to separate polar analytes. This removes the green benefits of SFC and destroys its otherwise unique ability to use the highly desirable universal flame ionization detector (FID) and others. These limitations can seriously constrain SFC users in the pharmaceutical, petroleum, and polymer industries, which are prevalent in Canada.      We will develop a new separation method for SFC that we discovered and patented. It is based on using water as a novel stationary phase and does not employ organic modifiers but only pure supercritical CO2. The method analyzes polar molecules well and is FID compatible, making it potentially very useful. Our work will critically advance this approach and its capabilities, and allow it to analyze important classes of molecules that are currently problematic. For instance, we will expand on altering the water stationary phase composition to enable chiral molecule separations, which are essential in drug discovery. This will open new ways to customize pharmaceutical separations and large-scale drug purification. We will also explore the promising potential of this water phase to separate unsaturated organic compounds from their saturated analogs. This could greatly assist in the interference free analysis of compounds like unsaturated fatty acids in complex oils. Through altering the water phase pH, efforts will also be made to separate and analyze organic bases, which are of broad importance to petrochemical, pharmaceutical, and other industries. In a parallel approach, we will make an unconventional attempt to actively alter the water stationary phase pH during separations in order to manipulate analyte retention. If it works, it could allow for the ultimate control in separations, where analytes are eluted on demand. Such an advance could have huge impact in the ability to analyze for target substances in large complex matrices, such as naphthenic acids or amines in heavy oil. A powerful new sulfur detector that we invented will also be examined with SFC in a related approach. These efforts will greatly simplify regulatory analysis of sulfur compounds in complex samples like crude oil, giving a competitive edge to petrochemical users, and open exciting new routes for the gas phase detection of related species, such as chemical warfare agents. The proposed work will train 6 students per year.