The invention concerns a method for determining the presence and quantity of an amine-based additive in fluids, particularly aqueous fluids used in hydrocarbon recovery such as drilling fluids, drill-in fluids, completion fluids, and the like. It was discovered that, after isolating the amine-based additive, the amount of clay stabilizer is linearly dependent upon the spectrometric count of its peak fluorescent spectrum. The method is reproducible and is not bothered by the presence of lignosulfonate and/or lignite which interferes with conventional methods.