The presentations will provide an in depth review of the sampling and analysis of gas and liquid phase samples using atomic fluorescence spectrometry for offline and online applications. The focus of the lecture will be on how to conduct the most accurate analysis on various streams during the gas and oil processing and also during petrochemical production. Examples will be provided of mercury mass balance studies and the effectiveness of mercury removal techniques. The impacts of mercury on plant operation will be explained in relation to the interpretation of Hg data generated.