title: Cosolutes effects on aqueous two-phase systems equilibrium formation studied by physical approaches.
abstract: The effect of urea and sodium salts of monovalent halides on the aqueous polyethyleneglycol solution and binodal diagrams of polyethyleneglycol-potassium phosphate (polyethyleneglycol of molecular mass 1500, 4000, 6000 and 8000) were studied using different physical approaches. The effect of these solutes on the binodal diagram for polyethyleneglycol-potassium phosphate was also investigated. The cosolutes affected in a significant manner the water structured around the ethylene chain of polyethyleneglycol inducing a lost of this. The equilibrium curves for the aqueous two-phase systems were fitting very well by a sigmoidal function with two parameters, which are closely related with the cosolute structure making or breaking capacity on the water ordered.
authors.affiliation: Physical-Chemistry Department, Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, FonCyT, CIUNR and CONICET, Suipacha 570, S2002RLK Rosario, Argentina.
authors.forename: M Guadalupe
authors.initials: MG
authors.lastname: Bertoluzzo
authors.forename: Rubén
authors.initials: R
authors.lastname: Rigatuso
authors.forename: Beatriz
authors.initials: B
authors.lastname: Farruggia
authors.forename: Bibiana
authors.initials: B
authors.lastname: Nerli
authors.forename: Guillermo
authors.initials: G
authors.lastname: Picó
mesh_terms: D003102:Colloids; D008970:Molecular Weight; D010710:Phosphates / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry; D012492:Salts / Q000737:chemistry; D012996:Solutions; D013816:Thermodynamics; D014508:Urea / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D003102:Colloids; D010710:Phosphates; D017680:Potassium Compounds; D012492:Salts; D012996:Solutions; D014867:Water; D011092:Polyethylene Glycols; D014508:Urea; C013216:potassium phosphate