Interactions in aqueous systems containing sodium cholate/calcium chloride mixtures

A systematic examination was made of the effects of sodium cholate and calcium chloride concentrations on the phases formed at 298 K. The phase diagram is a rather complex one, showing regions in which a single phase and a mixture of several phases coexist. At lower concentrations, cholate anions may exist as monomers or may be incorporated into an equimolar complex with calcium. Inside the precipitation region the appearance of various solid crystalline phases and of a liquid crystalline phase as well as of their mixtures can be observed. In the micellar region, calcium cholate (CaC2) coexists with cholate micelles, while in the region where a gel-like phase is formed the coexistence of CaC2, as solid crystalline phase, and of sodium cholate (NaC), as liquid crystalline phase, has been confirmed. The Krafft point for CaC2 as determined from specific conductivity measurements is 316 K. (C) 1996 Academic Press, Inc.