The analysis of cationic surfactants

Abstract Long‐chain cationic surfactants have become a very important class of industrial chemicals. These useful oleochemicals are usually based on vegetable oils and animal fats. They have many applications which include fabric softeners, antistatic agents, organo clays, emulsifiers, germicides, flotation, chemicals, corrosion inhibitors and foam depresents. The fatty quaternary ammonium compounds (quats) are by far the most important of this group of the commerical compounds. However, the fatty amine salts and amine oxides must also be classified as cationic surfactants. Although not as widely used as quats, they have special properties and uses which are often unique and useful. The various analytical methods used for these chemicals serves several objectives, including routine quality control, identification and characterization, determination in mixtures and formulations, determination at use level, and determination in the environment. In general, the objective of the analysis will determine what method will be used. Routine quality control procedures will most often use wet methods or some simple instrumental techniques. Identification and characterization of unknown cationic samples often require the most sophisticated of instrumental and chromatographic methods. Use level and environmental samples usually must be analyzed using the most sensitive methods. Often, colorimetric analysis is adequate. These samples often must undergo rigorous separation and celan‐up techniques before the method of choice can be used. The methodology for the analysis of fatty amines, amine oxides and quaternary ammonium compounds is reviewed with the various analytical objectives in mind. However, the main emphasis is placed on the quats.