Constant chemical potential titration.: Application to determination of nonionic surfactant concentrations

Titration is most often associated with the idea of a stoichiometric reaction. Generally, it is not considered possible to titrate a compound against a reagent unless the titration reaction is near total and if the result is not a product of well-defined stoichiometry. In this work, we illustrate that accurate titration is possible with compounds and reagents that interact to form an association of undefined stoichiometry, Our model is the potentio-metric titration of nonionic surfactant with cationic surfactant using a cationic surfactant-selective electrode. The result of this reaction is mixed micelles, the composition of which depends on the concentrations of the two surfactants in solution.