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Edson Anibal De Macedo - One of the best experts on this subject based on the ideXlab platform.

  • gibbs free energy of transfer of a Methylene Group on ucon sodium or potassium phosphate salts aqueous two phase systems hydrophobicity effects
    The Journal of Chemical Thermodynamics, 2010
    Co-Authors: Sara C. Silvério, José. A. Teixeira, Oscar Rodriguez, Edson Anibal De Macedo
    Abstract:

    Abstract The Gibbs free energy of transfer of a suitable hydrophobic probe can be regarded as a measure of the relative hydrophobicity of the different phases. The Methylene Group (CH2) can be considered hydrophobic, and thus be a suitable probe for hydrophobicity. In this work, the partition coefficients of a series of five dinitrophenylated-amino acids were experimentally determined, at 23 °C, in three different tie-lines of the biphasic systems: (UCON + K2HPO4), (UCON + potassium phosphate buffer, pH 7), (UCON + KH2PO4), (UCON + Na2HPO4), (UCON + sodium phosphate buffer, pH 7), and (UCON + NaH2PO4). The Gibbs free energy of transfer of CH2 units were calculated from the partition coefficients and used to compare the relative hydrophobicity of the equilibrium phases. The largest relative hydrophobicity was found for the ATPS formed by dihydrogen phosphate salts.

  • Gibbs free energy of transfer of a Methylene Group on {UCON + (sodium or potassium) phosphate salts} aqueous two-phase systems: Hydrophobicity effects
    Journal of Chemical Thermodynamics, 2010
    Co-Authors: Sara C. Silvério, Osvaldo Rodriguez, José. A. Teixeira, Edson Anibal De Macedo
    Abstract:

    The Gibbs free energy of transfer of a suitable hydrophobic probe can be regarded as a measure of the relative hydrophobicity of the different phases. The Methylene Group (CH2) can be considered hydrophobic, and thus be a suitable probe for hydrophobicity. In this work, the partition coefficients of a series of five dinitrophenylated-amino acids were experimentally determined, at 23 °C, in three different tie-lines of the biphasic systems: (UCON + K2HPO4), (UCON + potassium phosphate buffer, pH 7), (UCON + KH2PO4), (UCON + Na2HPO4), (UCON + sodium phosphate buffer, pH 7), and (UCON + NaH2PO4). The Gibbs free energy of transfer of CH2units were calculated from the partition coefficients and used to compare the relative hydrophobicity of the equilibrium phases. The largest relative hydrophobicity was found for the ATPS formed by dihydrogen phosphate salts. © 2010 Elsevier Ltd. All rights reserved.

Sara C. Silvério - One of the best experts on this subject based on the ideXlab platform.

  • gibbs free energy of transfer of a Methylene Group on ucon sodium or potassium phosphate salts aqueous two phase systems hydrophobicity effects
    The Journal of Chemical Thermodynamics, 2010
    Co-Authors: Sara C. Silvério, José. A. Teixeira, Oscar Rodriguez, Edson Anibal De Macedo
    Abstract:

    Abstract The Gibbs free energy of transfer of a suitable hydrophobic probe can be regarded as a measure of the relative hydrophobicity of the different phases. The Methylene Group (CH2) can be considered hydrophobic, and thus be a suitable probe for hydrophobicity. In this work, the partition coefficients of a series of five dinitrophenylated-amino acids were experimentally determined, at 23 °C, in three different tie-lines of the biphasic systems: (UCON + K2HPO4), (UCON + potassium phosphate buffer, pH 7), (UCON + KH2PO4), (UCON + Na2HPO4), (UCON + sodium phosphate buffer, pH 7), and (UCON + NaH2PO4). The Gibbs free energy of transfer of CH2 units were calculated from the partition coefficients and used to compare the relative hydrophobicity of the equilibrium phases. The largest relative hydrophobicity was found for the ATPS formed by dihydrogen phosphate salts.

  • Gibbs free energy of transfer of a Methylene Group on {UCON + (sodium or potassium) phosphate salts} aqueous two-phase systems: Hydrophobicity effects
    Journal of Chemical Thermodynamics, 2010
    Co-Authors: Sara C. Silvério, Osvaldo Rodriguez, José. A. Teixeira, Edson Anibal De Macedo
    Abstract:

    The Gibbs free energy of transfer of a suitable hydrophobic probe can be regarded as a measure of the relative hydrophobicity of the different phases. The Methylene Group (CH2) can be considered hydrophobic, and thus be a suitable probe for hydrophobicity. In this work, the partition coefficients of a series of five dinitrophenylated-amino acids were experimentally determined, at 23 °C, in three different tie-lines of the biphasic systems: (UCON + K2HPO4), (UCON + potassium phosphate buffer, pH 7), (UCON + KH2PO4), (UCON + Na2HPO4), (UCON + sodium phosphate buffer, pH 7), and (UCON + NaH2PO4). The Gibbs free energy of transfer of CH2units were calculated from the partition coefficients and used to compare the relative hydrophobicity of the equilibrium phases. The largest relative hydrophobicity was found for the ATPS formed by dihydrogen phosphate salts. © 2010 Elsevier Ltd. All rights reserved.

Robin D Rogers - One of the best experts on this subject based on the ideXlab platform.

  • solvent property characterization of poly ethylene glycol dextran aqueous biphasic systems using the free energy of transfer of a Methylene Group and a linear solvation energy relationship
    Industrial & Engineering Chemistry Research, 2005
    Co-Authors: Melanie L Moody, Heather D Willauer, Scott T Griffin, And Jonathan G Huddleston, Robin D Rogers
    Abstract:

    Aqueous biphasic systems (ABSs) composed of poly(ethylene glycol) (PEG) and dextran have long been proposed as useful liquid/liquid extraction systems for biological macromolecules. More recently, they have been proposed as useful partitioning systems for molecular characterization in quantitative structure activity relationships. In this context, the distribution ratios of a wide range of organic solutes differing in structure and functionality were measured in a PEG/dextran ABS and the results compared to the corresponding 1-octanol/water partition coefficients. The relative hydrophobicity of the phases was quantified from the free energy of transfer of a Methylene Group measured for a homologous series of alcohols. A linear free energy relationship based on Abraham's generalized solvation equation has been derived from the solute partitioning data, which allows a direct comparison to be made between the solvent properties of a PEG/dextran ABS and those of traditional solvent/water systems used, for exa...

  • solvent properties of aqueous biphasic systems composed of polyethylene glycol and salt characterized by the free energy of transfer of a Methylene Group between the phases and by a linear solvation energy relationship
    Industrial & Engineering Chemistry Research, 2002
    Co-Authors: Heather D Willauer, And Jonathan G Huddleston, Robin D Rogers
    Abstract:

    Aqueous biphasic systems (ABSs) composed of poly(ethylene glycol) (PEG) and salt have been examined as potential environmentally benign solvents for liquid/liquid extraction. These systems might also represent an alternative to traditional solvent/water systems used in quantitative structure−activity relationships (QSARs). For the application and design of these systems, it is important to have a thorough understanding of the nature of the solvent and its interactions with the solute, and thus, PEG/salt ABSs have been characterized to this end by a variety of methods. The relative hydrophobicities of several PEG/salt ABSs composed of different molecular weights of PEG (1000, 2000, and 3400) and a variety of inorganic salts [K3PO4, K2CO3, (NH4)2SO4, Li2SO4, MnSO4, ZnSO4, and NaOH] were measured by the free energy of transfer of a Methylene Group ΔGCH2. These results indicate that the relative hydrophobicity of a PEG/salt ABS is a function of only the degree of phase divergence of the biphasic system as exp...

José. A. Teixeira - One of the best experts on this subject based on the ideXlab platform.

  • gibbs free energy of transfer of a Methylene Group on ucon sodium or potassium phosphate salts aqueous two phase systems hydrophobicity effects
    The Journal of Chemical Thermodynamics, 2010
    Co-Authors: Sara C. Silvério, José. A. Teixeira, Oscar Rodriguez, Edson Anibal De Macedo
    Abstract:

    Abstract The Gibbs free energy of transfer of a suitable hydrophobic probe can be regarded as a measure of the relative hydrophobicity of the different phases. The Methylene Group (CH2) can be considered hydrophobic, and thus be a suitable probe for hydrophobicity. In this work, the partition coefficients of a series of five dinitrophenylated-amino acids were experimentally determined, at 23 °C, in three different tie-lines of the biphasic systems: (UCON + K2HPO4), (UCON + potassium phosphate buffer, pH 7), (UCON + KH2PO4), (UCON + Na2HPO4), (UCON + sodium phosphate buffer, pH 7), and (UCON + NaH2PO4). The Gibbs free energy of transfer of CH2 units were calculated from the partition coefficients and used to compare the relative hydrophobicity of the equilibrium phases. The largest relative hydrophobicity was found for the ATPS formed by dihydrogen phosphate salts.

  • Gibbs free energy of transfer of a Methylene Group on {UCON + (sodium or potassium) phosphate salts} aqueous two-phase systems: Hydrophobicity effects
    Journal of Chemical Thermodynamics, 2010
    Co-Authors: Sara C. Silvério, Osvaldo Rodriguez, José. A. Teixeira, Edson Anibal De Macedo
    Abstract:

    The Gibbs free energy of transfer of a suitable hydrophobic probe can be regarded as a measure of the relative hydrophobicity of the different phases. The Methylene Group (CH2) can be considered hydrophobic, and thus be a suitable probe for hydrophobicity. In this work, the partition coefficients of a series of five dinitrophenylated-amino acids were experimentally determined, at 23 °C, in three different tie-lines of the biphasic systems: (UCON + K2HPO4), (UCON + potassium phosphate buffer, pH 7), (UCON + KH2PO4), (UCON + Na2HPO4), (UCON + sodium phosphate buffer, pH 7), and (UCON + NaH2PO4). The Gibbs free energy of transfer of CH2units were calculated from the partition coefficients and used to compare the relative hydrophobicity of the equilibrium phases. The largest relative hydrophobicity was found for the ATPS formed by dihydrogen phosphate salts. © 2010 Elsevier Ltd. All rights reserved.

Heather D Willauer - One of the best experts on this subject based on the ideXlab platform.

  • solvent property characterization of poly ethylene glycol dextran aqueous biphasic systems using the free energy of transfer of a Methylene Group and a linear solvation energy relationship
    Industrial & Engineering Chemistry Research, 2005
    Co-Authors: Melanie L Moody, Heather D Willauer, Scott T Griffin, And Jonathan G Huddleston, Robin D Rogers
    Abstract:

    Aqueous biphasic systems (ABSs) composed of poly(ethylene glycol) (PEG) and dextran have long been proposed as useful liquid/liquid extraction systems for biological macromolecules. More recently, they have been proposed as useful partitioning systems for molecular characterization in quantitative structure activity relationships. In this context, the distribution ratios of a wide range of organic solutes differing in structure and functionality were measured in a PEG/dextran ABS and the results compared to the corresponding 1-octanol/water partition coefficients. The relative hydrophobicity of the phases was quantified from the free energy of transfer of a Methylene Group measured for a homologous series of alcohols. A linear free energy relationship based on Abraham's generalized solvation equation has been derived from the solute partitioning data, which allows a direct comparison to be made between the solvent properties of a PEG/dextran ABS and those of traditional solvent/water systems used, for exa...

  • solvent properties of aqueous biphasic systems composed of polyethylene glycol and salt characterized by the free energy of transfer of a Methylene Group between the phases and by a linear solvation energy relationship
    Industrial & Engineering Chemistry Research, 2002
    Co-Authors: Heather D Willauer, And Jonathan G Huddleston, Robin D Rogers
    Abstract:

    Aqueous biphasic systems (ABSs) composed of poly(ethylene glycol) (PEG) and salt have been examined as potential environmentally benign solvents for liquid/liquid extraction. These systems might also represent an alternative to traditional solvent/water systems used in quantitative structure−activity relationships (QSARs). For the application and design of these systems, it is important to have a thorough understanding of the nature of the solvent and its interactions with the solute, and thus, PEG/salt ABSs have been characterized to this end by a variety of methods. The relative hydrophobicities of several PEG/salt ABSs composed of different molecular weights of PEG (1000, 2000, and 3400) and a variety of inorganic salts [K3PO4, K2CO3, (NH4)2SO4, Li2SO4, MnSO4, ZnSO4, and NaOH] were measured by the free energy of transfer of a Methylene Group ΔGCH2. These results indicate that the relative hydrophobicity of a PEG/salt ABS is a function of only the degree of phase divergence of the biphasic system as exp...