This control method is used for the analysis of diethanolamine (DEA) in solutions used to remove acid gases, such as hydrogen sulfide and carbon dioxide from hydrocarbon streams. The method utilizes an acid-base titration that determines basic constituents, i.e., free amine and amine associated with weak acids. The value obtained is a measure of the potential efficiency of the solution to remove the above gases. The lower limit of detection is less than 1 wt-%.