Titrations of non-ionic surfactants with sodium tetraphenylborate using the orion surfactant electrode

Abstract

A method for the determination of non-ionic surfactants is described. The poly(oxyethylene) portion of non-ionic surfactants forms psuedo-crown compounds in the presence of barium ions. The Orion surfactant electrode is used as the end-point indicator in titrations of these compounds with sodium tetraphenylborate. Stoichiometric constants for the reaction of barium non-ionic complexes with sodium tetraphenylborate have been established. The results of titrations of several non-ionic surfactants indicate that an average of 5.16 oxyethylene units will form a complex with one tetraphenylborate ion. Empirical titration factors have also been established for several classes of non-ionic surfactants and used in the analysis for the non-ionic content of commercial detergent products. An average recovery of 96.4% was obtained in the analysis of three standard detergent products. The described method has been used successfully in the routine determination of non-ionic surfactants.