Raymond L. Henry

Osmotic behavior of poloxamer 407 and other non-ionic surfactants in aqueous solutions

Solutions of non-ionic surfactants were prepared in water and buffer. The osmotic behavior of these solutions were studied by measuring their osmolality, using the freezing point depression method. Graphical representation of osmolality versus concentration depicted non-linear parabolic curves that were applied to logarithmic and polynomial mathematical models. One such surfactant, poloxamer 407, was selected and studied in solutions of water and buffer. We observed curves of similar profile, which were attributed to its interaction and association in aqueous solution. In the liquid state the osmotic influence is due to the surfactant-water interaction. When the solution is warmed and converted to the gel state, the polymer is taken out of play and the osmotic influence is due to the aqueous solution only. This phenomenon was supported by in vitro red blood cell tonicity observations.