Wilks Enterprise has published a new White Paper that discusses various oil in water methods and their correlation with regulatory methods. While the amount of oil in water is highly regulated -- it can also be a challenging measurement. It is complicated by the fact that oil comes in many forms and the measurement is defined by the particular regulatory method. When EPA 1664 is the regulatory method, the “oil” is anything that is extracted into hexane and remains after the hexane has been evaporated and shows up as weight. In regions where infrared analysis is the defining method, the “oil” is whatever is extracted into the solvent and has carbon-hydrogen bonds that absorb infrared light at a specific frequency. Each method is looking at different properties of oil and can potentially give different results.