POLARITY OF NONIONIC SURFACTANTS AS DETERMINED BY GAS-CHROMATOGRAPHY

The use of gas chromatography to determine the polarity of model and commercial surface active agents is discussed. Various polarity parameters are presented, and their positive and negative features are discussed. Effects of chromatographic conditions upon these polarity parameters are presented. The use of the polarity index and the retention index of ethanol and methanol, and the sum of the first five McReynolds constants is favorable. Relationships between various polarity parameters and between these parameters and the hydrophile lipophile balance (HLB) are discussed. The effect of surfactant structures upon their polarity parameters is presented. Polarity parameters can be used to estimate the HLB of surfactants and they can be used as analytical coefficients to characterize the average structure of nonionic surfactants. Some properties of nonionic surfactants can be predicted from their polarity parameters. They can be also used to predict and interpret the behavior of extractants and surfactants at various liquid/liquid interfaces. They can be used to discuss the kinetic data and the mechanism of metal extraction by various extractants.