Regulators worldwide are imposing tighter and more comprehensive emissions requirements in response to increasing concern about the impact of airborne pollutants. Fenceline emissions have traditionally been monitored through a combination of off-line laboratory techniques, such as GC-MS or HPLC, which lack the time resolution, responsiveness, and comprehensiveness of analysis to provide timely information on such a dynamic and complex matrix. Online monitoring is an important tool to ensure the root cause of air quality perturbations can be rapidly identified and addressed.