Coprecipitating ammonium-iron(III)-hexacyanoferrate(II) from aqueous dispersion with albumin and trichloroacetic acid

Ammonium-iron(III)-hexacyanoferrate(II) (AFCF) is a caesium-binding agent u sed, for example, to prevent the absorption of radioactive caesium from the alimentary tract of domestic animals. Owing to its colloidal nature, its s eparation from aqueous solution with standard methods is tedious, complicat ing in vitro studies. A new and simple method for separating AFCF from wate r and water-soluble components was developed, based on quantitative copreci pitation with bovine albumin and trichloroacetic acid (TCA). The resulting precipitate and supernatant can be separated with low centrifugal forces. B ound caesium follows AFCF into the precipitate, whereas free caesium remain s in solution. This makes the method a potential tool in the study of the t hermodynamic and kinetic properties of AFCF-caesium interactions in vitro. Effects of different factors, such as concentrations of components, speed a nd duration of centrifugation and temperature, are described.