Abstract: The present invention proposes a process for extracting and determining nitrogenous and acidic compounds in various types of petroleums, derivatives or thermal degradation products, and in process waters before the production/refining phase. When the methodology is applied to petroleum and byproducts, the process comprises the extraction steps (1); separation (2); pre-concentration (3); and analysis (4). When the methodology is applied to thermal degradation products, there is a need for a previous step to simulate the heating of petroleum containing different chemicals (if necessary) with the purpose of promoting thermal degradation of the species present and of the petroleum, and generating nitrogen compounds with simpler composition.