General Solvation Model Research Articles

Evaluation of fatty tissue representative solvents in extraction of medical devices for chromatographic analysis of devices’ extractables and leachables based on Abraham general solvation model

Extraction solvents used in chemical characterization (i.e., extractables and leachables testing, E&L) of fatty tissue-contacting medical devices for biocompatibility assessment per ISO 10993 have been studied by Abraham general solvation models. Chemically suitable alternative solvents to fatty tissues in solvation properties (solubility, partition, extraction, etc.) have been proposed based on Abraham's organic solvent system coefficients for water and air to condensed organic solvent phases. This evaluation is built upon the conclusion by Abraham, Acree Jr and Cometto-Muñiz that olive oil is chemically corresponding to fatty tissues. However, olive oil, if used as an extraction solvent to simulate fatty tissues, is in general not analytically expedient (realistic) per ISO 10993-18 (2020) for chromatographic analysis, and it is critical to seek alternative solvents to olive oil to perform the extraction. Although nonpolar solvents such as alkanes have been proposed and used as alternative solvents to vegetable oils, they are not equivalent to olive oil in solvation properties. Due to the practical challenge in chromatographic analysis of oil samples and the difference in migration kinetics of E&L between oil and organic solvents, the computational approach is the only realistic option to evaluate chemically alternative solvents to olive oil to simulate fatty tissue extraction. By comparing Abraham solvent system coefficients for water and air to condensed organic solvent phases distribution, a five-dimensional space distance (D) between solvents and olive oil as a reference solvent is calculated using Abraham and Martin equation to predict alternative or similar solvents to olive oil. The results of the calculation are further evaluated using E&L solubility ratio between solvents and olive oil, taking into consideration of solvent safety and physical properties. It is concluded from the study that butanone and dioxane are chemically the most suitable alternative or representative solvents to olive oil. They can be used as fatty tissue representative solvents in chemical characterization study of medical device. As Abraham solvation model is solvent system specific, not solute specific, the conclusions from this study are considered as universal.

Evaluation of blood simulating solvents in extractables and leachables testing for chemical characterization of medical devices based on Abraham general solvation model

Extraction vehicles (simulating solvents) used in chemical characterization (i.e., extractables/leachables testing) of blood-contacting medical devices for biocompatibility assessment per ISO 10993 have been studied by Abraham general solvation models. Chemically equivalent solvents to blood in solvation properties (solubility, partition, extraction, etc.) have been proposed based on Abraham’s organic solvent system coefficients for water and air to condensed organic solvent phases. This evaluation is built upon the conclusion by Abraham, Acree Jr and Cometto-Muñiz that water saturated n-butanol (called wet n-butanol) is chemically corresponding to blood. Although wet n-butanol can be directly used to replace blood in an extraction study (such as a simulated-use extraction study per ISO 10993-18 (2020)), it can be beneficial to have alternate solvents to wet n-butanol (butan-1-ol) when chromatographic interference is practically significant. By comparing Abraham solvent system coefficients for water to condensed organic solvent phases distribution, a five-dimensional space distance (D) between solvents and reference solvent (wet n-butanol) is calculated using Abraham and Martin equation to predict equivalent or similar solvents (to wet n-butanol). It is concluded from the study that ethanol/water (60/40, V/V) and ethanol/water (50/50, V/V) are chemically equivalent or quite similar to wet n-Butanol. Other two less similar solvents are ethylene glycol and ethanol/water (70/30, V/V). Thus, n-butanol, ethanol/water (60/40, V/V) and ethanol/water (50/50, V/V) can be used as blood simulating solvents in chemical characterization study of medical device. In certain situations, ethylene glycol might be desirable as an alternate solvent, as it is not a mixture. As Abraham solvation model is general (solvent system specific, not solute specific), the conclusions from this study are considered as universal.

Activity coefficients at infinite dilution for organic solutes dissolved in two 1-alkylquinuclidinium bis(trifluoromethylsulfonyl)imides bearing alkyl side chains of six and eight carbons

Infinite dilution activity coefficients and gas-to-liquid partition coefficients are reported for 47 and 45 organic probe molecules dissolved in 1-hexylquinuclidinium bis(trifluoromethylsulfonyl)imide ([Quin6]+[Tf2N]−) and 1-octylquinuclidinium bis(trifluoromethylsulfonyl)imide ([Quin8]+[Tf2N]−), respectively, as determined by inverse gas chromatography in the temperature range of 313K to 353K. The measured partition coefficient data were converted to water-to-liquid partition coefficients using standard thermodynamic relationships and published gas-to-water partition coefficient data. Both sets of calculated partition coefficient data for each ionic liquid solvent were analyzed in terms of the Abraham general solvation model. Mathematical correlations derived from the Abraham model described the measured partition coefficient data to within 0.14 or fewer log units.

LSER-based modeling vapor pressures of (solvent + salt) systems by application of Xiang-Tan equation

The study deals with modeling the vapor pressures of (solvent+salt) systems depending on the linear solvation energy relation (LSER) principles. The LSER-based vapor pressure model clarifies the simultaneous impact of the vapor pressure of a pure solvent estimated by the Xiang-Tan equation, the solubility and solvatochromic parameters of the solvent and the physical properties of the ionic salt. It has been performed independently two structural forms of the generalized solvation model, i.e. the unified solvation model with the integrated properties (USMIP) containing nine physical descriptors and the reduced property-basis solvation model. The vapor pressure data of fourteen (solvent+salt) systems have been processed to analyze statistically the reliability of existing models in terms of a log-ratio objective function. The proposed vapor pressure approaches reproduce the observed performance relatively accurately, yielding the overall design factors of 1.0643 and 1.0702 for the integrated property-basis and reduced property-basis solvation models.

Predicting Abraham model solvent coefficients.

BackgroundThe Abraham general solvation model can be used in a broad set of scenarios involving partitioning and solubility, yet is limited to a set of solvents with measured Abraham coefficients. Here we extend the range of applicability of Abraham’s model by creating open models that can be used to predict the solvent coefficients for all organic solvents.ResultsWe created open random forest models for the solvent coefficients e, s, a, b, and v that had out-of-bag R2 values of 0.31, 0.77, 0.92, 0.47, and 0.63 respectively. The models were used to suggest sustainable solvent replacements for commonly used solvents. For example, our models predict that propylene glycol may be used as a general sustainable solvent replacement for methanol.ConclusionThe solvent coefficient models extend the range of applicability of the Abraham general solvation equations to all organic solvents. The models were developed under Open Notebook Science conditions which makes them open, reproducible, and as useful as possible.Graphical Chemical space for solvents with known Abraham coefficients.Electronic supplementary materialThe online version of this article (doi:10.1186/s13065-015-0085-4) contains supplementary material, which is available to authorized users.

The charge-asymmetric nonlocally determined local-electric (CANDLE) solvation model.

Many important applications of electronic structure methods involve molecules or solid surfaces in a solvent medium. Since explicit treatment of the solvent in such methods is usually not practical, calculations often employ continuum solvation models to approximate the effect of the solvent. Previous solvation models either involve a parametrization based on atomic radii, which limits the class of applicable solutes, or based on solute electron density, which is more general but less accurate, especially for charged systems. We develop an accurate and general solvation model that includes a cavity that is a nonlocal functional of both solute electron density and potential, local dielectric response on this nonlocally determined cavity, and nonlocal approximations to the cavity-formation and dispersion energies. The dependence of the cavity on the solute potential enables an explicit treatment of the solvent charge asymmetry. With four parameters per solvent, this "CANDLE" model simultaneously reproduces solvation energies of large datasets of neutral molecules, cations, and anions with a mean absolute error of 1.8 kcal/mol in water and 3.0 kcal/mol in acetonitrile.

Modeling vapor pressures of solvent systems with and without a salt effect: An extension of the LSER approach

A new polynomial vapor pressure approach for pure solvents is presented. The model is incorporated into the LSER (linear solvation energy relation) based solvation model framework and checked for consistency in reproducing experimental vapor pressures of salt-containing solvent systems. The developed two structural forms of the generalized solvation model (Senol, 2013) provide a relatively accurate description of the salting effect on vapor pressure of (solvent+salt) systems. The equilibrium data spanning vapor pressures of eighteen (solvent+salt) and three (solvent (1)+solvent (2)+salt) systems have been subjected to establish the basis for the model reliability analysis using a log-ratio objective function.The examined vapor pressure relations reproduce the observed performance relatively accurately, yielding the overall design factors of 1.084, 1.091 and 1.052 for the integrated property-basis solvation model (USMIP), reduced property-basis solvation model and concentration-dependent model, respectively. Both the integrated property-basis and reduced property-basis solvation models were able to simulate satisfactorily the vapor pressure data of a binary solvent mixture involving a salt, yielding an overall mean error of 5.2%.

Thermochemical investigations of solute transfer into ionic liquid solvents: updated Abraham model equation coefficients for solute activity coefficient and partition coefficient predictions

Experimental data have been compiled from the published chemical and engineering literature pertaining to the infinite dilution activity coefficients, gas solubilities and chromatographic retention factors for solutes dissolved in ionic liquid (IL) solvents. Chromatographic retention factors for 45 solutes on a 1-butyl-1-methylpyrrolidinium tricyanomethanide IL gas–liquid chromatographic stationary phase are included in the compilation. The published experimental data were converted to gas-to-IL and water-to-IL partition coefficients and correlated with the ion-specific equation coefficient version of the Abraham general solvation model. Ion-specific equation coefficients were calculated for 40 different cations and 16 different anions. The calculated ion-specific equation coefficients describe the experimental gas-to-IL and water-to-IL partition coefficient data to within 0.123 and 0.149 log units, respectively.

Solvation-based modeling vapor pressures of (solvent + salt) systems with the application of Cox equation

A solvation model framework, based on the LSER (linear solvation energy relationship) principles, is proposed for correlating vapor pressures of (solvent+salt) systems. The LSER method basely uses a linear combination of several solvatochromic indices of solvents to describe their physical properties. The assumption inherent in the solvation-based vapor pressure approach is attributed to an additional effect of several physical quantities, i.e. the vapor pressure of a pure solvent estimated by the Cox equation, the salt concentration, the solvatochromic indicators of the solvent and the physical properties of the ionic salt species. It has been performed independently two structural forms of the generalized solvation model, i.e. the integrated property-basis model using nine physical descriptors USMIP (the unified solvation model with the integrated properties) and the reduced property-basis one. Also, a simplified concentration-dependent vapor pressure model is presented. The observed vapor pressure data of fifteen (solvent+salt) and two (solvent (1)+solvent (2)+salt) systems have been processed to establish the basis for the model reliability analysis using a log-ratio objective function. The proposed vapor pressure approaches reproduce the observed performance relatively accurately, yielding the overall design factors of 1.065 and 1.072 for the solvation-based models with the integrated and reduced properties and 1.017 for the concentration-based model, respectively. Both the integrated property-basis and reduced property-basis solvation models were able to simulate satisfactorily the vapor pressure data of a binary solvent mixture involving a salt, yielding an overall mean error of 5.7%.

Mathematical correlations for describing enthalpies of solvation of organic vapors and gaseous solutes into ionic liquid solvents

Previously reported ion-specific equation coefficients for the Abraham general solvation model are updated using recently published enthalpy of solution data for organic solutes dissolved in room temperature ionic liquids (RTILs). Reported for the first time are equation coefficients for 1-hexyloxymethyl-3-methylimidazolium, 1,3-dihexyloxymethylimidazolium, 3-methyl-N-butylpyridinium, tris(pentafluoroethyl)trifluoro phosphate, and tetracyanoborate ions. In total 12 sets of cation-specific and 10 sets of anion-specific equation coefficients have been determined for each model. The derived correlations describe the 942 experimental enthalpies of solvation to within a standard deviation of about 1.65 kJ/mol.

Linear Free Energy Relationship Correlations for Enthalpies of Solvation of Organic Solutes into Room-Temperature Ionic Liquids Based on the Abraham Model with Ion-Specific Equation Coefficients

Mathematical correlations have been developed for describing the enthalpy of solvation of organic solutes into room-temperature ionic liquids (RTILs) based on the Abraham general solvation model with ion-specific equation coefficients. The derived correlations contain six cation-specific and six anion-specific equation coefficients that were determined through regression analyses. The derived equations correlated the observed enthalpies of solvation data to within a standard deviation of about 1.7 kJ/mol. The nine sets of cation-specific and eight sets of anion-specific equation coefficients that have been calculated can be combined to yield equations capable of predicting the enthalpies of solvation of organic solutes and gases in 72 different RTILs.

Linear Free Energy Relationship Correlations for Room Temperature Ionic Liquids: Revised Cation-Specific and Anion-Specific Equation Coefficients for Predictive Applications Covering a Much Larger Area of Chemical Space

Previously reported ion-specific equation coefficients for both the Abraham general solvation model and Goss modified Abraham model are updated using recently measured activity coefficient, gas chromatographic retention factor, and solubility data for solutes dissolved in room temperature ionic liquids (RTILs). Reported for the first time are equation coefficients for 1-propyl-2,3-dimethylimidazolium cation, and octylsulfate and thiocyanate anions. In total nine sets of cation-specific and eight sets of anion-specific equation coefficients have been determined for each model. The derived correlations describe the 976 experimental gas-to-RTIL partition coefficients to within a standard deviation of 0.12 log units and the 955 experimental water-to-RTIL partitions to within a standard deviation of 0.15 log units.

Thermochemical behavior of dissolved carboxylic acid solutes: part 5 – mathematical correlation of 3,5-dinitrobenzoic acid solubilities with the abraham solvation parameter model

In connection with the thermochemical behavior of dissolved carboxylic acid solutes, the Abraham general solvation model is used to calculate the numerical values of the solute descriptors for 3,5-dinitrobenzoic acid from experimental solubilities in organic solvents.

Solubility of crystalline nonelectrolyte solutes in organic solvents: mathematical correlation of 3-nitrobenzoic acid solubilities with the Abraham general solvation model

The Abraham general solvation model is used to calculate the numerical values of the solute descriptors for 3-nitrobenzoic acid from experimental solubilities in organic solvents. The mathematical correlations take the form of log ( C S / C W ) = c + r R 2 + s π 2 H + a Σ α 2 H + b Σ β 2 H + v V x log ( C S / C G ) = c + r R 2 + s π 2 H + a Σ α 2 H + b Σ β 2 H + l ⁢ log L ( 16 ) where C S and C W refer to the solute solubility in the organic solvent and water, respectively; C G is a gas-phase concentration; R 2 is the solute excess molar refraction; V x is McGowan volume of the solute; Σ α 2 H and Σ β 2 H are measures of the solute hydrogen-bond acidity and hydrogen-bond basicity; π 2 H denotes the solute dipolarity/polarizability descriptor; and L (16) is the solute gas-phase dimensionless Ostwald partition coefficient into hexadecane at 298 K. The remaining symbols in the above expressions are known solvent coefficients, which have been determined previously for a large number of gas/solvent and water/solvent systems. We estimate R 2 as 0.9900 and calculate V x as 1.1059, and then solve a total of 48 equations to yield π 2 H=1.1800, Σ α 2 H=0.7300, Σ β 2 H=0.5200 and log L (16)=5.6011. These descriptors reproduce the experimental data with a standard deviation of only 0.082 log units.

Thermochemical behavior of dissolved carboxylic acid solutes: part 4 – mathematical correlation of 4-nitrobenzoic acid solubilities with the abraham solvation parameter model

The Abraham general solvation model is used to calculate the numerical values of the solute descriptors for 4-nitrobenzoic acid from experimental solubilities in organic solvents. The mathematical correlations take the form of where C S and C W refer to the solute solubility in the organic solvent and water, respectively, C G is a gas phase concentration, R 2 is the solute excess molar refraction, V x is the McGowan volume of the solute, and are measures of the solute hydrogen-bond acidity and hydrogen-bond basicity, denotes the solute dipolarity/polarizability descriptor, and L (16) is the solute gas phase dimensionless Ostwald partition coefficient into hexadecane at 298 K. The remaining symbols in the above expressions are known solvent coefficients, which have been determined previously for a large number of gas/solvent and water/solvent systems. We estimate R 2 as 0.9900, set = 0.6800 and calculate V x as 1.1059, and then solve a total of 51 equations to yield = 1.5200, = 0.4000, and log L (16) = 5.7699. These descriptors reproduce the observed log(C S /C W ) and log(C S /C G ) values with a standard deviation of only 0.076 log units.

Thermochemical behavior of dissolved Carboxylic Acid solutes: Part 2 – Mathematical Correlation of Ketoprofen Solubilities with the Abraham General Solvation Model

The Abraham general solvation model is used to calculate the numerical values of the solute descriptors for ketoprofen from experimental solubilities in organic solvents. The mathematical correlations take the form of where CS and CW refer to the solute solubility in the organic solvent and water, respectively, C G is a gas phase concentration, R 2 is the solute excess molar refraction, V x is McGowan volume of the solute, Σ and Σ are measures of the solute hydrogen-bond acidity and hydrogen-bond basicity, denotes the solute dipolarity/polarizability descriptor and L (16) is the solute gas phase dimensionless Ostwald partition coefficient into hexadecane at 298 K. The remaining symbols in the above expressions are known solvent coefficients, which have been determined previously for a large number of gas/solvent and water/solvent systems. We estimate R 2 as 1.6500 and calculate V x as 1.9779, and then solve a total of 19 equations to yield = 2.260, Σ = 0.550 and Σ = 0.890. These descriptors reproduce the 19 observed log(C S /C W ) values with a standard deviation of only 0.123 log units. The log(C S /C G ) correlation could not be used in the present study because of both lack of experimental vapor pressure data for ketoprofen at 298.15 K, and lack of the Ostwald partition coefficient for ketoprofen into hexadecane.

Thermochemical behavior of dissolved Carboxylic Acid solutes: Part 3 – Mathematical Correlation of 2-Methylbenzoic acid solubilities with the Abraham Solvation Parameter Model

The Abraham general solvation model is used to calculate the numerical values of the solute descriptors for 2-methylbenzoic acid from experimental solubilities in organic solvents. The mathematical correlations take the form of where CS and CW refer to the solute solubility in the organic solvent and water, respectively, CG is a gas phase concentration, R 2 is the solute excess molar refraction, Vx is McGowan volume of the solute, are measures of the solute hydrogen-bond acidity and hydrogen-bond basicity, denotes the solute dipolarity/polarizability descriptor and L (16) is the solute gas phase dimensionless Ostwald partition coefficient into hexadecane at 298 K. The remaining symbols in the above expressions are known solvent coefficients, which have been determined previously for a large number of gas/solvent and water/solvent systems. We estimate R 2 as 0.7300 and calculate Vx as 1.0726, and then solve a total of 47 equations to yield = 0.8400, = 0.4200, = 0.4400 and log L (16) = 4.6770. These descriptors reproduce the observed log(C S /C W ) and log(C S /C G ) values with a standard deviation of only 0.076 log units.

Thermochemical behavior of dissolved carboxylic acid solutes: Solubilities of 3-methylbenzoic acid and 4-chlorobenzoic acid in organic solvents

The Abraham general solvation model is used to correlate the solubility behavior of 3-methylbenzoic acid and 4-chlorobenzoic acid in alcohol and ether solvents. The mathematical correlations take the form of [Formula: see text] [Formula: see text] where CS and CW refer to the solute solubility in the organic solvent and water, respectively; CG is a gas-phase concentration; R2 is the solute excess molar refraction; Vx is the McGowan volume of the solute; ΣαH2 and ΣβH2 are measures of the solute hydrogen-bond acidity and hydrogen-bond basicity; πH2 denotes the solute dipolarity–polarizability descriptor; and L(16) is the solute gas-phase dimensionless Ostwald partition coefficient into hexadecane at 298 K. The remaining symbols in the above expressions are known solvent coefficients, which have been determined previously for a large number of gas–solvent and water–solvent systems. The Abraham general solvation model was found to describe the experimental solubility data and published literature partitioning data of 3-methylbenzoic acid and 4-chlorobenzoic acid to within overall standard deviations of 0.079 log units and 0.085 log units, respectively. Key words: 3-methylbenzoic acid solubilities, 4-chlorobenzoic acid solubilities, alcohol solvents, partition coefficients, molecular solute descriptors, solubility predictions.

Solubility of Crystalline Nonelectrolyte Solutes in Organic Solvents: Mathematical Correlation of Acetylsalicylic Acid Solubilities with the Abraham General Solvation Model

Solubility of Crystalline Nonelectrolyte Solutes in Organic Solvents: Mathematical Correlation of Acetylsalicylic Acid Solubilities with the Abraham General Solvation Model

Solubility predictions for crystalline polycyclic aromatic hydrocarbons (PAHs) dissolved in organic solvents based upon the Abraham general solvation model

The Abraham general solvation model is used to predict the saturation solubility of crystalline non-electrolyte solutes in organic solvents. The derived equations take the form of log C S C W =c+rR 2+sπ 2 H +a∑α 2 H +b∑β 2 H +vV x log C S C G =c+rR 2+sπ 2 H +a∑α 2 H +b∑β 2 H +l log L 16 where C S and C W refer to the solute solubility in the organic solvent and water, respectively, C G is a gas phase concentration, R 2 the solute’s excess molar refraction, V x the McGowan volume of the solute, ∑ α 2 H and ∑ β 2 H are the measures of the solute’s hydrogen-bond acidity and hydrogen-bond basicity, π 2 H denotes the solute’s dipolarity/polarizability descriptor, and L 16 is the solute’s gas phase dimensionless Ostwald partition coefficient into hexadecane at 298 K. The remaining symbols in the above expressions are known coefficients, which have been determined previously for a large number of gas/solvent and water/solvent systems. Computations show that the Abraham general solvation model predicts the observed solubility behavior of pyrene, acenaphthene and fluoranthene to within an average absolute deviation of about +45%.