Saturated Solubilities Research Articles

Exploring solubility and energetics: Dissolution of biologically important l-threonine in diverse aqueous organic mixtures across the temperature range of 288.15 K to 308.15 K

This research provides a thorough investigation into the solubility behavior and solution thermodynamics of l-threonine in significant organic solvent systems. The work was done on measuring the actual solubility and subsequently calculating overall transfer solvation free energetics (∆Genergetic0i) and transfer entropies (∆St0i) at a temperature of 298.15 K. These measurements were performed as l-threonine transitioned from water to different water-organic mixed solvents systems. The saturated solubilities of l-threonine were determined using the ‘gravimetric method’ at five equidistant temperatures namely 288.15 K, 293.15 K, 298.15 K, 303.15 K and 308.15 K. By analyzing the data on solubility, we further obtained the different energies involved in solvation related issues. In the case of single solvents, the nature of solubility of l-threonine was observed like: dimethylsulfoxide (DMSO) < acetonitrile (ACN) < N, N-dimethylformamide (DMF) < ethylene glycol (EG) < water (H2O), irrespective of the experimental conditions. Specifically, at 298.15 K, the solubilities of l-threonine in single solvents were found to be as follows: 0.8220 mol per kg of water, 0.3101 mol per kg of EG, 0.1337 mol per kg of DMF, 0.1107 mol per kg DMSO and 0.1188 mol per kg of ACN. This research critically examines the relationship between the experimental saturated solubility of l-threonine and the complex properties influencing its solvation energy in diverse aqueous organic solvent systems.

Exploring the solubility and solvation energetics of L-phenylalanine across diverse aqueous organic solutions at five equidistant temperatures (288.15 K to 308.15 K)

This research elucidates comprehensive insights into the dissolution nature and solvation energetics of L-phenylalanine across distinct solvent environments. Specifically, the investigation encompasses saturated solubility measurements and the subsequent derivation of overall transfer free energies (ΔGt0(i)) and entropies (ΔSt0(i)) at 298.15 K, of L-phenylalanine from an aqueous medium to aqueous solutions comprising protic ethylene glycol (EG), dipolar aprotic N,N-dimethylformamide (DMF), acetonitrile (ACN), and dimethyl sulfoxide (DMSO). In this study the 'gravimetric method' was used to find the saturated solubilities of L-phenylalanine at five equidistant temperatures (288.15 K to 308.15 K). These experimental solubility measurements serve as the foundational dataset for the subsequent determination of transfer energies. The investigated drenched or equilibrium solubility data was applied to ascertain the solvation energies. In case of pure solvent, we get the solubility trend of L-phenylalanine as follows: ACN < DMSO < DMF < EG < water, at any temperature. At 298.15 K, we found the solubilities of L- phenylalanine in pure solvents like water, EG, DMF, DMSO and ACN are 0.1675, 0.0911, 0.0888, 0.0850 and 0.0811 mol·kg−1 respectively. A pivotal facet of this study involves the examination of the correlation between the saturated solubility of L-phenylalanine and the intricate characteristics of its solvation energetics across diverse aqueous organic solvent systems.

Solubility and dissolution thermodynamics of L-histidine and L-tryptophan in aqueous ethanol solution at five equidistant temperatures

This study highlights the saturated solubilities and dissolution thermodynamical properties of two very important amino acids viz. L-histidine and L-tryptophan having various roles in many field in pure aqueous and aqua-ethanol medium at particular as well as range of temperature employing static gravimetric method which is very systematic and error free. Finding confirms that L-histidine shows more solubility in water rich region and L-tryptophan shows more solubility in organic rich region. L-tryptophan has an extra benzene ring which makes L-tryptophan more covalent than L-histidine moiety. Consequently, solubility of former in water rich region becomes low. In connection with those mentioned properties other various physiochemical parameters like co-solvent diameter, apparent dipole moment, apparent molar volume, solvent diameter etc. are also estimated. All observations are explained clearly on the ground of several solution related interactions namely cavity forming, solvent-solvent, solvent-solute interactions etc. Both total and chemical transfer Gibbs energies as well as entropies are calculated and explained to give support to stability and variation of solubility in both aqueous and aqua-ethanol media.

Effect of Spray Drying Method on the Properties of Glimepiride-loaded Solid Dispersion

Glimepiride (GLI) is a third-generation sulfonylurea class antidiabetic drug that has low aqueous solubility. The objective of this study was to evaluate the effect of solvents in the development of GLI-loaded solid dispersions (GLISD) using spray drying technique. Two GLI-SD were prepared by adding GLI, polyvinylpyrrolidone (PVP K30), and sodium lauryl sulfate (SLS) in an ethanol/water mixture (solvent evaporation, SE) and water only (surface attached, SA). Intrinsic saturated solubilities and in-vitro dissolution were evaluated and compared to the GLI powder and physical mixture (PM). In addition, physicochemical studies such as scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction were also evaluated. We found that the solubility of GLI was significantly improved by both the preparation methods. The SE method showed 4,960-fold improvement while the SA method displayed 2,900-fold enhancement, which is equivalent to the PM. The in-vitro dissolution studies showed that both methods had a higher release rate, about 1.3-fold for SE and 2-fold for SA, as compared to pure GLI powder. However, GLI release slightly decreased with time for the SA method. Furthermore, solid-state characterizations also revealed that most of the crystalline drug was transformed to the amorphous form in both GLI-SD. Thus, these results indicate that choice of the solvent system plays an important role in the spray drying technique which affects the solubility, dissolution, and crystallinity of poorly soluble drugs such as GLI.

Influence of Cr3C2 and VC Content on WC Grain Size, WC Shape and Mechanical Properties of WC-6.0 wt. % Co Cemented Carbides.

In this paper, the influences of Cr3C2/VC content on WC grain size, WC grain shape and mechanical properties of WC–6 wt. % Co cemented carbides were investigated. The results showed that the grain size first rapidly decreased and then slightly decreased with the increasing Cr3C2/VC content, and VC led to finer grain size and narrower size distribution. HRTEM/EDS analysis of the WC/Co interface indicates that the segregation concentration of V is much larger than that of Cr, which may be a strong response to the higher inhibition efficiency of VC. The addition of Cr3C2 induced triangular prism shape WC grains while VC generated stepped triangular prism grains. Despite the grain growth inhibitor (GGI) mechanisms of Cr3C2/VC have been extensively studied in the literature, the doping amount, especially the doping limit, has not been systematically investigated. In this work, the saturated solubilities of Cr and V in cobalt binder phase along with carbon content hare been predicted based on thermodynamic calculations. Based on the theoretical calculations, the doping amount of Cr3C2/VC is designed to be gradually increasing until more or less over their maximum solubilities in the binder phase, thereby investigating the subsequent microstructure and mechanical properties. When the doping of Cr3C2/VC exceeds the maximum solubility in Co phase, Co-rich Cr-carbides and Co-deficient V-carbides would form respectively, which were detrimental to the transverse rupture strength (TRS) and impact toughness. The hardness increased with the increasing Cr3C2/VC content, while the fracture toughness decreased with the increasing Cr3C2/VC content. The TRS initially enhanced and then declined, but the stepped triangular prism shape grains and low fraction of WC/Co interface in WC–6Co–VC cemented carbide led to a more pronounced decline in the TRS. The sample with 0.6 wt. % Cr3C2 addition had good comprehensive mechanical properties, its hardness, fracture toughness and TRS were 1880 kg/mm2, 9.32 MPa·m1/2 and 3450 MPa, respectively.

Thermodynamic properties and thermodynamic modelling for aqueous mixed system containing lithium metaborate and sodium metaborate

The pH values, solubilities and water activities in the system LiB(OH)4–NaB(OH)4–H2O at 323.15 K were investigated. The mole fractions of boron species were calculated in the aqueous borate solutions, and the distribution and relevant mechanism were also discussed. The solubility diagrams in the ternary system were drawn at 323.15 K. The phase diagram consists of two single salt regions for LiB(OH)4 and NaB(OH)4·2H2O, one invariant point co-saturated with the above salts. On the basis of the Pitzer model, the Pitzer binary parameters and mixing parameters were fitted with the water activities, saturated vapour pressure and solubilities in the ternary system. The dissolution equilibrium constants (Ksp) of LiB(OH)4 and NaB(OH)4·2H2O were calculated using the experimental solubility data. The calculated solubilities with the parameters and Ksp agree well with the experimental data.

Solubility, Preferential Solvation, and Solvent Effect of Micoflavin in Aqueous Mixtures of Dimethylsulfoxide, Isopropanol, Propylene Glycol, and Ethanol

The saturated thermodynamic solubilities of micoflavin in four mixtures of dimethyl sulfoxide (DMSO, 1) + water (2), isopropanol (1) + water (2), propylene glycol (PG, 1) + water (2), and ethanol (...

Electrolytic Effect on the Solubility and Solvation Thermodynamics of l-Serine and l-Isoleucine in Aqueous Media

By the analytical gravimetric technique, the equilibrium saturated solubilities of l-serine and l-isoleucine in aqueous solutions of sodium nitrate (NaNO3) and potassium nitrate (KNO3) were measure...

Mode of hydrophilic and hydrophobic interactions of DL-Tyrosine, DL-Leucine, DL-Isoleucine and DL-Threonine in aqueous binary mixture of dipolar aprotic acetonitrile

The saturated solubilities of DL- Tyrosine, DL-Leucine, DL-Isoleucine and DL-Threonine in binary aqueous dipolar aprotic acetonitrile solvent were estimated by ‘formol titrimetry’ at nine equidistant temperatures under 0.1 MPa pressure. The chemical effects of the standard transfer energetics of these amino acids obtained after elimination of cavity forming, dipole-dipole and dipole-induced dipole interaction effect from the total, are useful to know about chemical stability of it in such system and solvent-solvent interaction therein. Hydrophobic and hydrophilic interactions of standard transfer Gibbs free energies and entropies, as obtained after subtraction of dispersion from chemical interaction are guided by the attached side chains.

Solubility and Thermodynamics of Solute–Solvent Interactions of Some Amino Acids in Aqueous Sodium Bromide and Potassium Bromide Solutions

The study presents the saturated solubilities of four amino acids such as glycine, dl-alanine, dl-valine, and dl-serine in water media containing sodium bromide and potassium bromide electrolytes at standard temperature (298.15 K) which were evaluated by applying the “gravimetric method”. Various physicochemical and thermodynamical parameters such as enthalpy of solvation, free energy change, density, molar volume, solvent diameter, cosolvent diameter, apparent dipole moment of aqueous electrolyte systems, mole fraction of salt and solvent, mean molecular weight of electrolyte solvent and isothermal expansibility constant of aqueous electrolytes were estimated at standard temperature (298.15 K). The characteristics and degree of solubilities of the experimental molecules in water media in the presence of NaBr and KBr were examined by means of the salting-in effect which was further justified by relative solubility and salting-in constants. Various reasonings influencing the solubility were introduced and ...

Solubility and solute-solvent interactions of dl-alanine and dl-serine in aqueous potassium nitrate solutions

Present study described the saturated solubilities of dl-alanine and dl-serine in pure and aqueous binary potassium nitrate solutions, were estimated by an analytical ‘formol titration’ procedure at 298.15K. Various physicochemical and thermodynamical parameters like free energy change, density, molar volume, solvent diameter, co-solvent diameter, probable dipole moment of aqueous electrolyte systems, etc., were calculated at 298.15K. The nature and degree of solubilities of such amino acids in aqueous potassium nitrate solutions were analyzed in terms of salting-in effect which was further justified by relative solubility and salting-in constants. Finally, thermodynamics of solute-solvent interactions in terms of transfer Gibbs free energetics were calculated and described the relative stability of the amino acids in pure and binary mixture of solvents.

Evaluation and correlation of solubility and solvation energetics of DL-phenylalanine and DL-serine in water and aqueous ethylene glycol solutions

The saturated solubilities, the standard total transfer free energies (ΔGt0(i)) and entropies (ΔSt0(i)) of transfer of DL-serine and DL-phenylalanine from water to aqueous mixtures of protic ethylene glycol (EG) at 298.15K are reported in the present study. The transfer energies have been determined from the saturated solubility of the amino acids, which have been measured at five equidistant temperatures from 288.15 to 308.15K by ‘analytical gravimetric method’. The chemical parts of free energies (ΔGt, ch0(i)) and entropies (ΤΔSt, ch0(i)) of transfer of the amino acids have been computed by subtracting the cavity effects and dipole-dipole interaction effects from the total transfer free energy. The correlation of saturated solubility and the characteristics of the involved solvation energetics of the amino acids in aquo-organic solvent system are studied and also discussed critically in the present study.

Evaluation and correlation of solubility and solvation thermodynamics of glycine, dl-alanine and dl-valine in aqueous sodium sulphate solutions at two different temperatures

In the present study the saturated solubilities of glycine, dl-alanine, and dl-valine in aqueous mixtures of Na2SO4 were determined at 298.15K and 323.15K by using an analytical ‘gravimetric method’. The nature and extent of such solubilities of the experimental amino acids in aqueous Na2SO4 solutions are discussed in the light of salting-in and salting-out effect and compared with the values of the same amino acids reported earlier. The physicochemical and chemical factors affecting the solubility results were suggested and correlated with the thermodynamical aspects and parameters. Finally the transfer Gibbs free energies were calculated and employed to discuss the relative stability of the amino acids in aqueous and aqueous electrolyte solution.

The chemical stability of L-isoleucine, L-threonine, and L-serine in aqueous solutions of KCl at 298.15 K

The experimental saturated solubilities of L-isoleucine, L-threonine, and L-serine in aqueous mixtures of a KCl solution at 298.15 K are presented in this article. The solubilities are measured by gravimetric method. In the present study the theoretical calculation of the standard transfer Gibbs free energy, cavity forming enthalpy of transfer, cavity forming transfer Gibbs free energy, dipole-dipole interaction effect have been computed. The chemical effects of the transfer Gibbs energies for the present amino acids have been obtained by subtracting the cavity effects and dipole-dipole interaction effects from the ΔGt0(i). The stability of the experimental amino acids in aqueous KCl in terms of thermodynamic parameters is explained.

Comparative study on solubility of glycine, DL-alanine, DL-nor-valine and DL-serine in aqueous solutions of NaF and KF at 298.15 K

The experimental saturated solubilities of glycine, DL-alanine, DL-nor-valine and DL-serine in aqueous mixtures of NaF and KF solutions at 298.15K were reported in the present study. The solubilities were measured by using an analytical ‘gravimetric method’. In the present manuscript the nature and extent of saturated solubilities of the experimental amino acids in aqueous NaF and KF were discussed in the light of salting-in and salting-out effect and compared with the same amino acids in other halides which were observed in literatures as well as in present study.

Cytotoxicity and enhancement activity of essential oil from Zanthoxylum bungeanum Maxim. as a natural transdermal penetration enhancer.

The aim of this present study is to investigate the effect of Zanthoxylum bungeanum oil (essential oil from Z. bungeanum Maxim.) on cytotoxicity and the transdermal permeation of 5-fluorouracil and indomethacin. The cytotoxicity of Z. bungeanum oil on dermal fibroblasts and epidermal keratinocytes was studied using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The rat skin was employed to determine the percutaneous penetration enhancement effect of Z. bungeanum oil on hydrophilic and lipophilic model drugs, i.e., 5-fluorouracil and indomethacin. The secondary structure changes of the rat stratum corneum (SC) were determined using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and saturated solubilities and SC/vehicle partition coefficients of two model drugs with and without Z. bungeanum oil were also measured to understand its related mechanisms of action. It was found that the half maximal inhibitory concentration (IC50) values of Z. bungeanum oil were significantly lower in HaCaT and CCC-ESF-1 cell lines compared to the well-established and standard penetration enhancer Azone. The Z. bungeanum oil at various concentrations effectively facilitated the percutaneous penetration of two model drugs across the rat skin. In addition, the mechanisms of permeation enhancement by Z. bungeanum oil could be explained with saturated solubility, SC/vehicle partition coefficient, and secondary structure changes of SC.

Evaluation of In Vitro Dissolution and In Vivo Oral Absorption of Drug Nanopowders Prepared by Novel Wet-Milling Equipment

In vitro dissolution and in vivo oral absorption studies were carried out in order to evaluate the effects of nanoparticulation. Omeprazole, albendazole and danazol nanopowders were prepared using novel wet-milling equipment, an ULTRA APEX MILL, with Pluronic F-68 or F-108 as dispersing agents, followed by lyophilization. An in vitro dissolution study showed that the dissolution rates of all nanopowders were drastically improved compared to the corresponding bulk powders, and their apparent saturated solubilities also increased compared to mixed powders consisting of bulk powders and dispersing agents. The AUCs after oral administration to rats of omeprazole nanopowders with Pluronic F-68 and F-108, and albendazole nanopowder with Pluronic F-68, were 1.93, 2.90 and 10.3 times higher, respectively than those for the corresponding bulk powders. The ULTRA APEX MILL can be a very useful tool for pharmaceutical techniques to enhance the dissolution and oral bioavailability of poorly water-soluble drugs. Keywords: Dissolution rate, nanopowder, oral absorption, poloxamer, poorly water-soluble drug, wet-milling, Omeprazole, albendazole, danazol, pharmacogenomics, BCS, nanoparticles, Plasma, HPLC, Hixson-Crowell equation, Pluronic F-108, JP 2nd solution, FaSSIF solution, CMC, Pharmacokinetic, Tmax, Cmax value

Solubility of disperse yellow 54 in supercritical carbon dioxide with or without cosolvent

Extraction of disperse yellow 54 with supercritical carbon dioxide was conducted at 393.2 K and 30 MPa over a wide range of contact times. Saturated solubilities of the disperse dyestuff in supercritical carbon dioxide with or without cosolvent were also measured over the temperature and pressure ranges of 353.2 K to 393.2 K and 15 MPa to 30 MPa. Either ethanol or dimethyl sulfoxide, up to 5 mol%, was used as a cosolvent. As evidenced from the experimental results, the magnitudes of equilibrium solubility can be effectively enhanced in the presence of both two cosolvents. Dimethyl sulfoxide was found to yield higher solubility enhancement. Cosolvent effects were discussed on the basis of the Kamlet-Taft solvatochromic solvent parameters of cosolvents. The saturated solubility data were correlated with the Chrastil and the Mendez-Santiago and Teja equations. The Chrastil model correlated the solubility data to about within the experimental uncertainty. The correlated results of the Mendez-Santiago–Teja model supported the consistency of the solubility data over the entire experimental conditions.

Measurements of the solubilities of derivatized amino acids in supercritical carbon dioxide

The solubilities of phenylalanine and tyrosine in supercritical carbon dioxide (SCCO 2) were measured after derivatization as the N-acetyl amino acid ethyl ester, N-carbobenzoxy amino acid and N-acetyl amino acid. Using an SCCO 2 flow system, a measuring method of the saturated solubilities of the derivatized amino acids was established in which the contact height of the extraction cell, i.e. a packed column, is increased till the concentration of a derivatized amino acid at the exit of the cell reaches a plateau. The solubilities of N-acetyl phenylalanine ethyl ester (APEE) exceeded 0.001 mole fraction, which is higher than those of caffeine produced in industrial SCCO 2 processes. A possible way of separating the amino acid mixtures using polarity differences in different amino acid side chains was demonstrated using the solubility data of the N-acetyl-amino acid ethyl esters in SCCO 2, as the solubilities of APEE are higher than those of N-acetyl tyrosine ethyl ester by two orders of magnitude.

The effect of β-cyclodextrins on the permeation of diclofenac from supersaturated solutions

Supersaturation is a very useful method of enhancing the permeation of drugs across membranes such as skin, because unlike other methods, it does not interfere with the ultrastructure of the stratum corneum. Many drugs are able to form inclusion complexes with β-cyclodextrins (β-CDs) and this study investigates the anti-nucleating effects of these compounds on supersaturated solutions of diclofenac. The ability of various βCDs to form inclusion complexes with diclofenac was assessed by measuring their saturated solubilities. Solutions containing hydroxypropyl β-cyclodextrin (HPβ-CD, with a molar substitution of 0.9) produced a 7.5-fold increase in the solubility of diclofenac, which suggested that a strong complex was formed between the two compounds. This association was characterized using differential scanning calorimetry. Permeation across silicone membranes of these saturated solutions of diclofenac in the presence of the different βCDs produced similar flux values suggesting that the overall activity was also similar. The effect of different molar ratios of HPβ-CD and diclofenac, and the anti-nucleating effect of HPβ-CD (both on its own and in combination with a known anti-nucleant, hydroxypropylmethyl cellulose (HPMC)) on the diffusion of diclofenac across silicone membranes was investigated. HPβ-CD appears to have a stabilizing effect on supersaturated solutions of diclofenac as a co-ingredient with HPMC.