RELATIONSHIP BETWEEN COMPLEX COMPOSITIONS AND THEIR BACTERIAL-ACTIVITY IN BINARY MIXTURE OF SODIUM 1-OCTANESULFONATE AND LANTHANUM(III) CHLORIDE

The composition of complexes formed in aqueous solution consisting of a binary mixture of sodium 1-octanesulfonate (NaOS) and lanthanum(III) chloride (LaCl3) was studied by measuring surface tension, electric c onductivity and proton spin-lattice relaxation time. In the molar rati o of octanesulfonic anion and lanthanum(III) cation below 0.1, a 3:1-c omplex was formed. The area per the 3:1-complex adsorbed at air-water interface was 208 Angstrom(2) on the assumption of a monomolecular lay er. The formations of 2:1- and 1:1-complex were found in the vicinity of 0.5 and above 1.2 of LaCL3/NaOS, respectively. Whereas, when LaCl3 was added to 15 mol m(-3) NaOS, the bactericidal activity of the mixed solution against Escherichia coli ATCC 25922 markedly increased with increasing the molar ratio (LaCl3/NaOS) up to 1.0 and finally remained constant. The contribution of complexes on the bactericidal activity was estimated at 1.5:1:1 from the combination of data of complex distr ibutions and bactericidal activity.