Advanced separation and detection methods for supercritical fluid chromatography

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Replacing organic solvents with environmentally clean solvents is a growing area of concern and research. Supercritical fluids are widely used in this regard. They have gas and liquid-like properties that yield remarkable solvating and mass transport capabilities. Many laboratories coping with mounting hazardous waste and slow sample throughput are now using them to replace conventional isolation and analysis methods. Supercritical carbon dioxide is very popular due to its low cost, relative environmental compatibility and mild critical parameters. In supercritical fluid chromatography (SFC), it is used to transport sample components through a column that separates them for analysis, before it decompresses into a gas. In this way, SFC unites the dissolving power of liquid chromatography with a speed and separation capability similar to that of gas chromatography. However, supercritical carbon dioxide is non-polar and cannot well dissolve and separate polar molecules unless a polar modifier such as methanol is added. The flame ionization detector (FID) is very widely used in chromatography due to its excellent universal response towards organic compounds. Since methanol creates a noisy background signal in the FID, this detector cannot be used with modified SFC. Presently, the ability to separate polar compounds using modified supercritical carbon dioxide and detect them with the FID, or other novel universal detectors, would greatly assist various laboratories using SFC to monitor their processes and products. Frequent SFC users include the pharmaceutical, petroleum, and polymer industries, which are prevalent in Canada. Our research will: 1. Develop a new universal acoustic detector for modified SFC that can operate in the presence of methanol. 2. Evolve new methods of using only water (it has no FID response) and carbon dioxide to separate/analyze polar analytes with FID. 3. Exploit using short column SFC-FID methods to elute polar compounds without modifiers. And 4. Advance a potential new multiple flame detector for SFC to selectively sense sulfur and phosphorus analytes in organic solvents. We will compare the developed methods with current techniques, and validate them by analyzing various samples.