The solubilisation and inactivation of preservatives by non-ionic detergents

Abstract

Abstract A novel potentiometric method, which depends on the pH changes which occur when an acidic material is solubilised, has been used to determine the solubilisation of the weakly acidic preservative, p-hydroxybenzoic acid, in a non-ionic detergent. From the pH changes observed, the partition coefficient, Km, for the distribution of the un-ionised acid between the micellar and the aqueous phase has been calculated and found to be 2.8 × 103. Specific interaction between the acid and the detergent. to form a complex is shown not to be important. It is suggested that the arguments against specific interaction apply generally to other preservatives and non-ionic detergents.