Dialysis Method for Determining Preservative Distribution in Emulsions

Preservation of Solubilized and Emulsified Systems I: Correlation of Mathematically Predicted Preservative Availability with Antimicrobial Activity

“…Distribution of Chlorocresol between Mineral Oil and Water and i n Mineral Oil Emulsions Stabilized with Cetomacrogol-The experimental procedures for the determination of distribution coefficients and the dialysis technique for studying the distribution of a preservative in emulsions were described previously (7).…”

“…Garrett (3) suggested that an ultracentrifuge technique be used to determine the "operative partition coefficient" in the actual emulsion system and the equilibrium concentration of surfactant in the aqueous phase as a function of the total surfactant concentration. However, studies using a three-chamber dialysis cell (7), which permitted direct estimation of the distribution of a preservative and surfactant between the oil, micellar, and aqueous phases of an emulsion, demonstrated excellent agreement between observed and predicted values of [Db] when the initial (i.e., total) surfactant concentration and K,", obtained by simple partition between the oil and water phases, were substituted into the equation.…”

“…Mathematical models have been developed that predict the preservative concentration required in a surfactant solution (1-3) or an emulsion (2)(3)(4)(5)(6)(7)(8)(9). These models were based on the assumption that antimicrobial activity is a function of the free (unbound or nonmicellar) preservative concentration in the aqueous phase.…”

The Preservation of Cosmetic and Pharmaceutical Creams

“…For example, Bean et al (1969) have derived an expression for calculating preservative activity in emulsions or creams which incorporates oil :water ratio, partition of preservative between these phases and its interaction with the emulsifying agent (surfactant) present (Equation 1). Kazmi & Mitchell (1971, 1976…”