Activity of Water and Osmotic Coefficients for Two- and Three-Basic Amino Acid Ternary Solutions

Osmotic coeffs. of ternary systems amino acid-electrolyte-water; aminoethanoic acid (glycine) + NaCl + H2O; aminoethanoic acid + KCl + H2O; aminoethanoic acid + NaNO3 + H2O; aminoethanoic acid + NaSCN + H2O; aminoethanoic acid + NaCOOCH3 + H2O; (S)-2-aminopentanedioic acid sodium salt (sodium L-glutamate) + NaCl + H2O; (S)-2-aminobutanedioic acid sodium salt (sodium L-aspartate) + NaCl + H2O; (S)-2-aminopentanedioic acid sodium salt + KCl + H2O; (S)-2-aminobutanedioic acid sodium salt + KCl + H2O, are inferred from vapor pressure osmometry measurements performed at T = 310.15 K

Anion effect on glutamate solutions at 298.15 and 310.15 K as deduced from vapor pressure measurements

Osmotic coefficients are inferred from vapor pressure osmometry measurements that were performed for the ternary systems sodium glutamate–sodium thiocyanate–water varying the concentration of NaGlu and NaSCN (mNaGlu = 0.09, 0.33, 0.57 mol/kg and mNaSCN = 0.1–1 mol/kg) at T = 298.15 K and 310.15 K. No strong interaction between glutamate and thiocyanate as suggested by theoretical MD and half-empirical quantum-chemical calculations (ab initio methods) can be concluded based on the experimental data. Absolute values of osmotic coefficients show mostly negative deviations from ideal state at both temperatures and for all sodium glutamate background concentrations. This is typical of a simple salt solution and a hint at only minor interactions between amino acid and salt

Thermodynamic Properties of L-Aspartates of Alkali and Alkali-Earth Metals in Aqueous Solutions at 298.15 and 310.15 K and Specific Cation Effects on Biomolecule Solvation

Vapor pressure osmometry was applied to the systems calcium l-aspartate ((S)-aminobutanedioic acid calcium salt) + water for varying molalities of Ca-l-Asp (m (Ca-l-Asp) = 0.01-1.02 mol center dot kg(-1)) and guanidinium hydrochloride (methanamidine hydrochloride) + sodium L-aspartate ((S)-aminobutanedioic acid sodium salt) + water, varying the molalities of GndmCl and Na-l-Asp (m (Na-l-Asp) = 0.1, 0.25, 0.4, 0.57 mol center dot kg(-1) and m (GndmCl) = 0.1-1.1 mol center dot kg(-1)) at T = 298.15 K and 310.15 K. From vapor pressure osmometry, activities of water, and the corresponding osmotic coefficients of the mixtures Ca-l-Asp + water and Na-l-Asp + GndmCl + water have been calculated, both being directly related to the chemical potentials of the different species and therefore to their Gibbs energy. Mean molal ion activity coefficients were obtained from experimental data fits with the Pitzer equations and the corresponding dual and triple interaction parameters were derived for the Ca-l-Asp + water binary system. beta ((2)) Pitzer parameters different from zero are required for Ca-l-Asp in water to reproduce the osmotic coefficient decrease with increasing concentration. Mean Spherical Approximation parameters accounting for Coulomb and short range interactions that describe the calcium and magnesium aspartates and glutamates are given. The decrease in the chemical potential of the aspartates corresponds to the Hofmeister series: NaAsp > Mg(Asp)(2) > CaAsp. A strong interaction between amino acid and salt due to specific dispersion interactions in amino acid salt systems containing guanidinium based salt has been revealed that is in agreement with MD and half-empirical quantum-chemical calculations

Osmotic Coefficients of Two Amino Acid Magnesium Salts at 298.15 and 310.15 K

The concentration dependence of the vapor pressures of magnesium l-glutamate and magnesium l-aspartate solutions has been studied with the help of vapor pressure osmometry measurements, performed as a function of salt concentration in the range m (i) = 0.01-0.43 and m (i) = 0.01-0.30 mol center dot kg(-1), respectively, at T = 298.15 and 310.15 K. From these experimental results, the activities of water and the corresponding osmotic coefficients have been calculated for all systems investigated. Mean molal ion activity coefficients were obtained from experimental data fits with the Pitzer equations and the corresponding dual and triple interaction parameters were derived. beta ((2)) Pitzer parameters different from zero are required where the osmotic coefficient decreases strongly with increasing concentration at 298.15 and 310.15 K. beta ((1)) and beta ((2)) analysis shows that the interaction nature is different for magnesium aspartate and magnesium glutamate solutions (the ratio of repulsion/attraction parts is different). The decrease in the chemical potential of the glutamates corresponds to the Hofmeister series: KGlu > NaGlu > Mg(Glu)(2) > Ca(Glu)(2)

Activity of water and osmotic coefficients of histidine derivatives in aqueous solutions at 310.15 K

From the data of vapor pressure osmometry the activity of water, osmotic coeffs., and the values of activity coeffs. of two derivs. of histidine: N-Boc-L-histidine (Boc-His-OH, m = 0.005-0.14 mol/kg-1) and N-Boc-L-histidine-Me ether (Boc-His-OMe, m = 0.005-0.05 mol/kg-1) are obtained in aq. solns. at 310.15 K. From the comparison of water activity and osmotic coeff. values it follows that Boc-His-OMe shows a more pronounced deviation from ideality than Boc-His-OH. Both components exhibit a stronger non-ideality than histidine and a weaker one than His/HCl. By means of potentiometric titrn. the acid-base properties of Boc-His-OMe are investigated and the ionization const. at 298.15 K is detd. The pK value related to the acid-base equil. of the nitrogen atom in the imido group of the imidazole ring is higher (6.47) than the corresponding value of histidine (6.00)

Activity of water, osmotic and activity coefficients of sodium glutamate and sodium aspartate in aqueous solutions at 310.15 K

The vapor pressures of aq. solns. of sodium L-glutamate (mi = 0.05-0.57 mol kg-1) and sodium L-aspartate (mi = 0.005-0.48 mol kg-1) were precisely measured at T = 310.15 K and the activity of water and the osmotic and activity coeffs. of the solutes were calcd. from these data. The concn. dependence of the osmotic coeffs. is described with the help of the Pitzer equation and the mean spherical approxn. (MSA). It is shown that it is possible to describe thermodn. properties of sodium aspartate and sodium glutamate solns. up to 0.5 molkg-1 with distance parameter R as the single fit parameter

Osmotic coefficients and activity coefficients in binary water/5-​(hydroxymethyl)​furfural and in ternary water/5-​(hydroxymethyl)​furfural/salt solutions at 298.15 K

This contribution is about the investigation of osmotic coefficients and the water activity of binary water/5-(hydroxymethyl)furfural (5-(hydroxymethyl)furan-2-carbaldehyde, HMF) and ternary water/5-(hydroxymethyl)furfural/salt (salt = NaCl or LiCl) solutions. Osmotic coefficients were determined by vapour pressure osmometry at 298.15 K and 975 hPa. HMF molalities ranged from (0.5 to 5) mol.kg(-1) in the binary solutions, while for the ternary solutions HMF molalities ranged from (1 to 5) mol.kg(-1)with salt molalities equal to (1 or 3) mol.kg(-1). The osmotic coefficients of the binary solutions were approximated with a Pitzer-type function to calculate activity coefficients of HMF in water. Osmotic coefficients of ternary systems were approximated according to the Zdanovskii-Stokes-Robinson (ZSR) semi-ideal mixing rule. Two-parameter fitting (third order terms in the power series) was applied to calculate solute activity coefficients in the ternary solutions. (C) 2019 Elsevier Ltd

Osmotic Coefficients and Activity Coefficients in Aqueous Aminoethanoic Acid-​NaCl Mixtures at 298.15 K

Osmotic coeffs. are inferred from vapor pressure osmometry measurements that were performed at T = 298.15 K for ternary amino acid-​electrolyte-​water systems with variation in the concns. of amino acid (aminoethanoic acid, glycine) and electrolyte (NaCl) up to high concns. of aminoethanoic acid (3 mol·kg-​1) and NaCl (3 mol·kg-​1)​. From the consideration of the Gibbs-​Duhem equation at mutual data treatment, interparticle interactions in ternary aminoethanoic acid-​NaCl-​water systems have been deduced in a wide concn. range. A two-​parameter fit (third order terms in the power series) according to Bower and Robinson is used for calcn. of component activity coeffs

Cation Effect on Water Activity of Ternary (S)-Aminobutanedioic Acid Magnesium Salt Solutions at 298.15 and 310.15 K

Vapor pressure osmometry was applied to the system aminomethanamidine hydrochloride (guanidinium hydrochloride, GndmCl) + (S)-aminobutanedioic acid hemimagnesium salt (magnesium l-aspartate, Mg-(L-Asp)(2)) + water for varying molalities of GndmCl and Mg-(L-Asp)(2) (m(Mg-(Asp)2) = 0.1, 0.2, and 0.3 mol/kg and m(GndmCl) = 0.11.2 mol/kg) at T = 298.15 and 310.15 K. From vapor pressure osmometry, activities of water, activity coefficients of water, and the corresponding osmotic coefficients of the mixtures Mg-(L-Asp)(2) + water and Mg-(L-Asp)(2) + GndmCl + water have been calculated, both being directly related to the chemical potentials of the different species and therefore to their Gibbs energy. Electrolyte perturbed-chain statistical associating fluid theory (ePC-SAFT) accounting for Coulomb and short-range (hard chain, dispersion, association) interactions was used to model the own experimental data of binary Mg-(L-Asp)(2) + water and ternary GndmCl + Mg-(L-Asp)(2) + water solutions. ePC-SAFT was further applied to model osmotic coefficients of NaGlu + KCl + water, NaGlu + NaCl + water, NaAsp + NaCl + water, NaAsp + KCl + water, aminoethanoic acid + NaNO3 + water, and aminoethanoic acid + NaSCN + water as well as thermodynamic properties of these solutions such as fugacity coefficients and activity coefficients of the mixture components. Without fitting any parameters to data of the ternary salt + aminoethanoic acid + water system, osmotic coefficients, phi, and activity coefficients of water, gamma(1), and aminoethanoic acid have been predicted, and phi and gamma(1) were in good agreement with the experimental data. In contrast, a negative binary interaction parameter k(ij) had to be introduced to model phi of ternary systems salt + amino acid salt + water in accurate agreement with the experimental data

Guanidinium Cation Effect on the Water Activity of Ternary (S)​Aminopentanedioic Acid Sodium Salt Solutions at 298.15 and 310.15 K

Vapor pressure measurements were applied to the systems guanidinium hydrochloride (methanamidine hydrochloride) + sodium L-glutamate (S-aminopenthanedioic acid sodium salt) + water at varying concentrations of GndmCl and Na-L-Glu (m(NaGlu) = 0.11.6 mol/kg; m (GndmCl) = 0.104 mol/kg, 0.301 mol/kg, 0.684 mol/kg) for two temperatures, T = 298.15 and 310.15 K. From the experimental results, activities of water, activity coefficients of water, and the corresponding osmotic coefficients of the mixtures Na-L-Glu + GndmCl + water have been calculated, both being directly related to the chemical potentials of the different components and therefore to their Gibbs energy. The modeling of the components chemical potentials in ternary GndmCl + Na-L-Glu + water solutions was done with the equation of state ePC-SAFT. Osmotic coefficients, fugacity coefficients, and activity coefficients of the mixture components were modeled. Experimental osmotic coefficient values demonstrate nonlinear concentration dependences with several extremums at different NaGlu molalities. The theoretical ePC-SAFT approach correctly describes the experimental data. Negative values of binary interaction parameters between the guanidinium ion and the amino acid salt were required in order to model osmotic coefficients of ternary systems salt + amino acid salt + water in good agreement with the experimental data, which shows that the non-Coulomb short-range interactions between ion and amino acid salt are very strong