Characterization of nonionic surfactants using supercritical fluid chromatography and carbon-13 nuclear magnetic resonance spectroscopy

Capillary supercritical fluid chromatography, using a carbon dioxide mobile phase and flame ionization detection, was employed for characterization of nonionic alcohol ethoxylate surfactants. Data from separations was used to calculate average molecular weights, degree of ethoxylation and distribution of telomers. The SFC approach was compared with carbon-13 nuclear magnetic resonance spectroscopy for evaluation of the same samples. The faster chromatographic technique permitted information to be obtained in the presence of materials which interfered with the NMR analysis, and provided a means of identifying the minor components of mixtures. The advantages and disadvantages of the methods are discussed and the complementary nature of the techniques illustrated.