Solution properties of a saponin (Acaciaside) in the presence of Triton X-100 and Igepal

The micellization of the saponin, Acaciaside, and its mixed-micelle formati on with Triton X-100 were studied by fluorimetric and microcalorimetric met hods. The energetics of the micellization process and the polarity of the m ixed micelles formed were evaluated. The nonideality of the mixed micelles (the deviation from Clint's equation) and the molecular interactions of Aca ciaside with Triton X-100 in the mixed micelles were quantified by Rubingh' s formalism in light of regular solution theory. The Acaciaside was found t o protect both Triton X-100 and Igepal from clouding. Using the clouding po int as the solubility limit of the surfactant there Triton X-100 and Igepal ) the energetics of the process have also been evaluated. Similar to hydrop hobic solutes, the entropies of solution of both Triton X-100 and Igepal ar e significantly negative.