An accurate, simple and rapid method for the determination of cationic surfactant was developed. The method is based on the formation of ion association between anionic dye and cationic surfactant. In this study, titan yellow and cetylpyridinium chloride were selected as dye and reactant surfactant, respectively. The ion association exhibits an absorption maximum at 400 nm. Beer's law was obeyed for cetylpyridinium chloride in the concentration range of 1-28 µg mL -1 and the detection limit was

more »

... 0.4 µg mL -1 . The proposed method was successfully applied to the determination of trace cationic surfactant in environmental water samples.