GENERAL-METHOD FOR THE STUDY OF SOLUTE SURFACTANT ASSOCIATION EQUILIBRIA OF VOLATILE SOLUTES BY HEADSPACE GAS-CHROMATOGRAPHY

A general methodology for measurement of solute-surfactant association s for volatile solutes based on headspace gas chromatography has been developed. A general theoretical model is also developed to treat the experimental data that requires no analytical solute standard. The mod el is applicable to any volatile solutes, especially very hydrophobic solutes such as n-alkylbenzenes, for which accurate aqueous standard s olutions cannot be prepared. Parameters such as solute-surfactant asso ciation constant, solute-micelles association constant and partition c oefficient, critical micelles concentration, intramicellar mole fracti on, and intramicellar activity coefficient of n-alkylbenzenes are obta ined as a function of aqueous surfactant concentrations.