Understanding the concentrations of sulfur and nitrogen is of critical importance in refining operations for two main reasons: regulatory purposes and process optimization. In most markets, worldwide regulatory agencies, such as the Environmental Protection Agency (EPA), limit the total amount of sulfur and nitrogen in fuel and refined products. This is because fuels containing high levels of sulfur release sulfur dioxide gas when burned, causing a range of health issues, as well as environmental issues, such as acid rain. As regulations push for cleaner fuels, greater pressure will be placed on manufacturers to better monitor pollutants, such as SO2 and NOx, through constant fuel analysis. Moreover, expensive catalysts utilized in refining processes degrade much faster in the presence of high sulfur and nitrogen concentrations. Fuel analysis can therefore help to optimize production processes.