The characterization of nonionic surfactants by NMR

The methods currently reported in the literature for the characterization of nonionic surfactants are usually applied to one portion of the molecule and require a knowledge of the other portion for complete identification. This indirect approach leaves much to be desired. A simple, rapid, and more direct method of characterization is to measure the proton signal intensity in high resolution nuclear magnetic resonance (NMR) spectra. This method determines the hydrophile to hydrophobe ratio without requiring standard samples for calibration or a prior knowledge of the hydrophobe. In addition, this method will frequently give much valuable information about the identity of the hydrophobe, such as the average chain length, the degree of branching, and the type of aromatic substitution, if any. This method has been applied to the characterization of the common types of commercial polyethylene oxide condensates. The application of NMR to the analysis of formulated detergent products is also discussed.