Linear Solvation Energy Relationship Model Research Articles

Extractability of Fumaric Acid by Tributyl Amine (TBA) in Ketones and Alcohols

Fumaric acid extraction from aqueous media by tributyl amine (TBA), which is an aliphatic amine, was studied at 298 K. Ketones (methyl isobutyl ketone (MIBK), heptan-2-one, octan-2-one) and alcohols (isoamyl alcohol, octan-1-ol, decan-1-ol) were selected as the diluent for dissolving TBA. Distribution ratio (KD), loading ratio (T), and extraction degree (DE) were calculated from experimental results. 96% efficiency was reached with isoamyl alcohol at 2.08 mol·kg–1 of TBA concentration. Futher, the linear solvation energy relationship (LSER) modeling cooperated with Hidebrand–Hansen solubility parameters was used for prediction KD of alcoholic diluents. The LSER model gave closeness prediction to experimental data.

Mechanisms and modeling of halogenated aliphatic contaminant adsorption by carbon nanotubes

This paper examines the adsorption of environmentally relevant halogenated aliphatic compounds using single-walled (SWCNT) and multi-walled carbon nanotubes (MWCNT), and the development of linear solvation-energy relationships (LSER) to examine those adsorption mechanisms. The poly-parameter LSER model was also compared to those previously generated for the adsorption of aromatic compounds by CNTs. The adsorption affinity of aliphatic compounds was greater on the SWCNT than MWCNT with similar oxygen contents. This was attributed to the pore-filling mechanism that was enhanced by higher micropore volume of the SWCNT bundles over the MWCNT bundles. LSER models showed that, at higher concentrations, B (the hydrogen bond accepting ability) was the most influential descriptor for both SWCNT and MWCNT. Other important descriptors were V followed by P, both of which exhibited a positive correlation with adsorption, indicating that their size and polarizability favors adsorption. The contribution of these descriptors to overall adsorption was 2–3 times less than the B. In comparison, V was the most important descriptor in the aromatic compound LSER models. This difference indicates that adsorbate hydrophobicity greatly affects the adsorption of aromatic compounds by CNTs, whereas, aliphatic compounds are affected by both the hydrophobic driving force and other interactions.

Effect of Diluents on the Extraction of Fumaric Acid by Tridodecyl Amine (TDA)

Separation of fumaric acid from aqueous media with tridodecyl amine (TDA), which is a long chain aliphatic amine, was carried out at 298 K. Different categories of diluents, ketones (methyl iso butyl ketone (MIBK), 2-heptanone, and 2-octanone) and alcohols (isoamyl alcohol, 1-octanol, and 1-decanol) were used to dissolve TDA. Distribution coefficients (KD), extraction efficiency (E), and loading factors (Z) were obtained as a function of experimental results. The most operative diluent was determined as heptan-2-one with the highest distribution coefficient (KD) value of 26.00. In additional to experimental studies, the linear solvation energy relationship (LSER) modeling with included Hidebrand–Hansen solubility parameters was applied for alcoholic diluents. Predicted data by LSER gave good agreement with experimental data.

Development of a new separation media using ultra-thin glassy carbon film modified silica

A self-polymerizable octatetrayne, 1,8-dialdehydebenzyl-1,3,5,7-octatetrayne, is synthesized and covalently attached to an amino-functionalized surface of silica particles. The silica particles with a monolayer coverage of octatetrayne were then thermally processed to various final temperatures of 200, 400 and 700°C. The amino-functionalization, covalent attachment of octatetrayne and thermal process of silica particles were monitored by scanning electron microscopy (SEM), infrared (IR) spectroscopy and thermogravimetric analysis (TGA). The thermally processed particles were then packed into a capillary column and evaluated as a stationary phase for HPLC. After chromatographic evaluation, the optimized temperature for thermal processing was determined to be 400°C, which provides the best modified silica particles SiO2-OCT-T400 with an ultra-thin glassy carbon film coating. The linear solvation energy relationship model indicated that the primary contributors in retention are dispersion and H-bond basicity. The application of SiO2-OCT-T400 as a stationary phase was further demonstrated by successful separation of nonpolar hydrocarbons mixture and a nucleosides mixture.

Characterization of novel metallacarborane-based sorbents by linear solvation energy relationships

Two novel metallacarborane-based stationary phases for high performance liquid chromatography were synthesized and characterized utilizing linear solvation energy relationships concept. Interactions taking place between selected probes (45 analytes) and the stationary phases and the mobile phases consisting of a mixture of acetonitrile with buffer were described by the linear solvation energy relationship model in a broad range of acetonitrile/buffer ratios. The interaction properties of the metallacarborane phases were compared with plain silica, the starting material for the preparation of the metallacarborane phases, and with a typical silica-based reversed-phase sorbent. It was clearly demonstrated that the metallacarborane sorbents provide qualitatively and quantitatively different interactions with respect to both the plain silica and reversed-phase stationary phase. It was shown that these novel phases might have also a separation potential in the area of hydrophilic interaction liquid chromatography.

Extraction Equilibria of Gibberellic Acid by Tridodecylamine Dissolved in Alcohols

Gibberellic acid (1.877·10–3 mol·kg–1) extraction from aqueous solution using tridodecylamine (TDA, 0.1 mol·kg–1 to 0.8 mol·kg–1) as extractant dissolved in three solvents (isoamyl alcohol, octane-1-ol, and decane-1-ol) at 298 K has been studied. Extraction parameters such as loading factor Z, extraction efficiency E, and distribution coefficient D, have been found using experimental data. The highest removal of gibberellic acid is found to be 96.37 % (D = 26.602, TDA = 0.5 mol·kg–1) with isoamylalcohol, 87.74 % (D = 7.160, TDA = 0.4 mol·kg–1) with octane-1-ol, and 71.87 % (D = 2.554, TDA = 0.4 mol·kg–1) with decane-1-ol. As per the experimental values of Z (1.19 to 6.52 with isoamyl alcohol, 0.85 to 5.26 with octane-1-ol, and 0.71 to 4.18 with decane-1-ol) and Bizek’ approach, the equilibrium complexation constants for 1:1 and 1:2 acid–TDA complexes have been determined. The linear solvation energy relationship (LSER) model is used to represent the extraction equilibrium of acid by TDA. D values are predicted using the LSER model parameters which fit the experimental results.

Intensification of Pyridine-3-carboxylic Acid Extraction Using N-Methyl-N,N-dioctyloctan-1-ammonium Chloride in Different Type of Diluents

The extraction of pyridine-3-carboxylic acid was investigated using N-methyl-N,N-dioctyloctan-1-ammonium chloride (TOMAC) with different diluents having distinct functional groups. Nine diluents were used in the study, i.e., octan-1-ol, nonan-1-ol, decan-1-ol, ethyl ethanoate, propyl ethanoate, heptan-2-one, octan-2-one, octane, and decane. The measurements were performed at room temperature (T = 298 K). The experimental results of batch extractions were used to calculate distribution coefficients (KD), loading factors (Z), and extraction efficiency (E). The maximum distribution coefficient (KD = 2.335) was obtained with octan-1-ol, and its extraction efficiency was 70.16 %. Besides, the highest loading factor was reached to a value of (0.179 at 0.440) mol·kg–1 equilibrium amine concentration. The results of the liquid–liquid equilibrium measurements were correlated by a linear solvation energy relationship (LSER) model which takes into account physical interactions. Experimental and model results of pyri...

Ionic liquids as stationary phases in gas chromatography--an LSER investigation of six commercial phases and some applications.

The separation properties of six novel stationary phases for gas chromatography, commercially available from Sigma-Aldrich (Supelco) and based on ionic liquids (ILs), were investigated. The linear solvation energy relationship model (LSER) was used to describe the molecular interactions between these stationary phases and 30 solutes. The solutes belong to different groups of compounds, like haloalkanes, alcohols, ketones, aromatics, aliphatics, and others. A good description of different interactions, as described by the LSER model, could be achieved. The calculated values of system constants for the ionic liquid phases were compared with constants of commonly used standard phases like a 5% phenyl/95% dimethyl siloxane and a polyethylene glycol phase. The solute descriptors are in good agreement with those found by previous authors who have used the LSER model for 44 different ionic liquids as stationary phase. The experiments were carried out at two temperatures to evaluate the influence on the phase parameters and separation characteristics. The interactions of different functional groups with the IL phases are discussed. These novel IL phases are a promising replacement of or an addition to common polar phases. Based on the evaluated phase properties, several possibilities for applications of these novel phases are shown.

Distribution of Penicillin G from the Aqueous Phase to the Organic Phase Using Amberlite LA-2 Extractant in Different Diluents

Benzyl penicillin, known as penicillin G (PG), is a β-lactam antibiotic and also a weak monocarboxylic acid. The penicillin G extraction from aqueous solution by Amberlite LA-2 in different diluents, that is, octan-1-ol, nonan-1-ol, 3-methyl-1-butanol, ethyl ethanoate, propyl ethanoate, 4-methylpentan-2-one, octan-2-one, octane, and decane has been studied. According to experimental results, some thermodynamic parameters, such as distribution coefficients (KD), loading factors (Z), and the extraction efficiency or degree (E), were calculated. The best extraction efficiency, distribution coefficient, and loading factor were determined using 3-methyl-1-butanol diluent as values of 92.63, 12.25, and 0.195, respectively. The linear solvation energy relationship (LSER) model was regressed for the experimental results of the distribution coefficient with the regression coefficient (R2) as 0.96. Besides, the equilibrium model for the extraction degree of alcohols has been applied and compared with experimental data.

Preparation and chromatographic evaluation of new branch-type diamide-embedded octadecyl stationary phase with enhanced shape selectivity

A novel branch-type diamide-embedded octadecyl stationary phase was prepared by facile amidation. The preparation of this new phase involves the synthesis of new bifunctional silane ligand and surface modification of spherical silica via anchoring of silane coupling agent. The obtained diamide-embedded octadecyl stationary phase demonstrated excellent hydrophobic selectivity, as well as enhanced shape and planarity selectivity in comparison to commercial polymeric and monomeric C18 phases, respectively, as revealed by the systematic investigation into its liquid chromatographic retention of isomeric polycyclic aromatic hydrocarbons. The applicability of this new stationary phase was further testified by the effective separation of isomeric compounds belong to different chemical classes, including chain isomers of alkylbenzenes, and positional isomers of substituted aromatics. An in-depth analysis of the separation mechanisms other than molecular shape recognition involved in the new stationary phase was performed using a linear solvation energy relationships model and compared with its monoamide and pure C18 counterparts correspondingly. The performance of the new stationary phase in quantitative analysis of phenols from real-world samples was also evaluated.

Development of in silico models for predicting LSER molecular parameters and for acute toxicity prediction to fathead minnow (Pimephales promelas)

Many chemicals with toxic effects to aquatic species are produced every year. To date, linear solvation energy relationship (LSER) models for toxicity prediction to aquatic species are limited to non-polar and polar narcotic compounds. In this study, the Verhaar scheme was used to classify chemicals into five modes of toxic actions. LSER models for predicting acute toxicity to fathead minnow were developed by identifying chemical functional groups that influence toxicity prediction of reactive chemicals. Moreover, the predictive models that can be used to estimate LSER molecular parameters have been developed by using quantum chemical and Dragon descriptors. All the predictive models were developed following the OECD guidelines for QSAR model development and validation, with a satisfactory goodness-of-fit, robustness and predictive ability. The McGowans volume was the most significant descriptor in the toxicity models. This study also inferred that, compounds with carbonyl group have different behaviors such that some can biodegrade in the organism while others do not biodegrade, which might be the reason for the difficulties in modeling the acute toxicity of reactive chemicals.

Novel imidazolium-embedded and imidazolium-spaced octadecyl stationary phases for reversed phase liquid chromatography

Two new stationary phases modified by alkylimidazoliums were prepared for the first time and characterized. One of the new phases was obtained via monomeric immobilization of octadecylimidazole to γ-chloropropyltrimethoxysilane modified silica to form polar-embedded phase; the other one was prepared by co-immobilization of two silane coupling agents (γ-chloropropyltrichlorosilane and octadecyltrichlorosilane) to silica, followed by quaternization of methylimidazole to form polar-spaced phase. This study was intended to compare the retention characteristics of these two stationary phases using linear solvation energy relationships model, as well as to examine the difference in selectivity by eluting alkylbenzenes, alkylnaphthalenes, condensed-ring and phenylene polynuclear aromatic hydrocarbons on both phases. Different effects of distributions of polar functional group and octadecyl chain were found to impact the chromatographic properties.

Separation of Oxoethanoic Acid from Aqueous Solution by N-Methyl-N,N-dioctyloctan-1-ammonium Chloride

Extractability of oxoethanoic acid (glyoxylic acid (GA)) from aqueous solutions, with N-methyl-N,N-dioctyloctan-1-ammonium chloride (Aliquat 336 (A336)) in various diluents, including isoamyl alcohol, octan-1-ol, nonan-1-ol, decan-1-ol, methyl ethyl ketone (MEK), diisobuthyl ketone (DIBK), hexan-2-one, toluene, kerosene, and n-hexane has been investigated. Batch extraction results were calculated and reported as distribution coefficients (KD), loading factors (Z), and extraction efficiency (E) at T = 298 K. These solvents with using A336 is more effective than a single solvent (KD ≫ 1). Hexan-2-one has been found to be the most effective diluent with the highest value of KD (17.37) at 1.31 mol·kg–1 concentration of A336. The results of the liquid–liquid equilibrium measurements were correlated by a linear solvation energy relationship (LSER) model which takes into account physical interactions and Freundlich and Langmuir equations. Experimental results of the oxoethanoic acid extraction are compared to mo...

Linear solvation energy relationships as classifier in non-target analysis – An approach for isocratic liquid chromatography

Linear solvation energy relationship (LSER) models are developed to characterize various HPLC columns and to predict retention of candidate compounds in non-target analysis of environmental samples. The models can be applied as classifier to exclude potential candidate structures with the same empirical formula. The application of the classifier was tested for a set of 19 isomers with empirical formula C12H10O2. The performance of the classifier was also demonstrated for a validation set of seven structural diverse compounds, where all potential candidates for the corresponding empirical formulas were included in the studies. Herein, the standard deviation of all compound descriptors of the respective candidate compounds was used as indication for potential exclusions on a certain column.

Development and validation of theoretical linear solvation energy relationship models for toxicity prediction to fathead minnow (pimephales promelas)

The acute toxicity predictive models are vitally important for the toxicological information used in the ecological risk assessments. In this study, we used Verhaar classification scheme to group compounds into five modes of toxic action. The quantum chemical descriptors that characterize the electron donor–acceptor property of the compounds were introduced into the theoretical linear solvation energy relationship (TLSER) models. The predictive models have relatively larger data sets, which imply that they cover a wide applicability domain (AD). All models were developed following the Organization for Economic Co-operation and Development (OECD) QSAR models development and validation guidelines. The adjusted determination coefficient (Radj2) and external explained variance (QEXT2) of the models were ranging from 0.707 to 0.903 and 0.660 to 0.858, respectively, indicating high goodness-of-fit, robustness and predictive capacity. The cavity term (McGowans volume) was the most significant descriptor in the models. Moreover, the electron donor–acceptor (E-TLSER) models are comparable to the TLSER models for the toxicity prediction to fathead minnow. Thus, the E-TLSER models developed can be used to predict acute toxicity of new compounds within the AD.

Applicability of the linear solvation energy relationships in the prediction for adsorption of aromatic compounds on activated carbons from aqueous solutions

A correlation capable of predicting adsorption capacities from the commonly available physicochemical properties of an adsorbate is of great significance to the engineering design of adsorption process. Apart from van der Waals force, dipole–dipole, induced dipole–dipole, and hydrogen-bonding donor–acceptor interactions exist between aromatic compounds (AOCs) and activated carbons. Correlations between the solubility normalized Freundlich affinity coefficients (KFS) of six AOCs on four activated carbons and the linear solvation energy relationship (LSER) variables of the AOCs were established. The modeling results demonstrate that the LSER model could be applied to predict the adsorption of AOCs on the activated carbons with KFS as a measure of the relative interaction strengths between the adsorbents and the adsorbates. Although derived from the properties of the adsorbates, the LSER modeling parameters were correlated with the surface chemistry of the studied activated carbons, suggesting that the LSER models could also reflect the natures of the adsorbents.

Reactive Extraction of Pyridine Carboxylic Acids with N, N-Dioctyloctan-1-Amine: Experimental and Theoretical Studies

The paper represents the equilibrium study on reactive extraction of pyridine-3-carboxylic acid (NA) and pyridine-4-carboxylic (iNA) acid from aqueous solution by N, N-dioctyloctan-1-amine (TOA) dissolved in five different diluents [dodecane, methyl benzene, decan-1-ol, 4-methylpentan-2-one (MIBK), and chloroform] at constant temperature of 298 ± 1 K. According to an experimental study, the extraction ability of diluents with TOA is found to be in the order of chloroform > decan-1-ol > MIBK > methyl benzene > dodecane for both acids. The highest extraction efficiency in terms of the distribution coefficient (K D) is found to be 45.15 and 25.79 for NA (0.12 mol · dm−3) and iNA (0.03 mol · dm−3), respectively. The values of loading ratio, Z (between 0.194 and 0.512) for both acids indicate the formation of 1:1 acid-TOA complexes in the organic phase. The values of the equilibrium constants (K 11) are determined from the experimental data using mass action law. These estimated values of K 11 are compared with the predicted values of K 11 from relative basicity and linear solvation energy relationship (LSER) models. The LSER model predicts the K 11 with an error limit of ±3% for NA and ±2% for iNA.

Prediction of gas chromatographic retention indices as classifier in non-target analysis of environmental samples

Kováts and Lee retention indices were predicted by the help of experimental and calculated boiling points and also by linear solvation energy relationship (LSER) models. The developed approaches should be applied as classifiers in non-target analysis of environmental samples to identify contaminants. To demonstrate the application as a classifier, an example of 14 isomers with empirical formula C12H10O2 was selected. Furthermore, seven compounds with different molecular composition were used to illustrate the application in non-target analysis, where progressive candidate exclusion is performed. The models help to reduce the number of potential candidates, and seem to be a useful addition to already existing classifiers.

Extraction of Gibberellic Acid from Aqueous Solution by Trioctyl Amine (TOA)

Gibberellic acid (GA) extraction from fermentation broth by trioctyl amine (TOA), which is a long chain aliphatic amine was studied. Initial concentration of GA was 0.65 g · L−1. This was performed using the fungi Gibberella fujikuroi in fermentation. Alcohols (isoamyl alcohol, n-octanol, n-decanol) have been used to dissolve TOA for preparing organic phases. All experiments were studied as batch extraction. Distribution coefficients (KD), loading factors (Z), and extraction efficiency (E) were calculated. The highest extraction efficiency, distribution coefficient, and loading factor were achived with isoamyl alcohol diluent as value of 80.6, 98.7, and 4.58, respectively. Furthermore, the linear solvation energy relationship (LSER) model including Hansen solubility parameters regressed to experimental results. The LSER model predicts a close resemblance of experimental data.

Using linear solvation energy relationship model to study the retention factor of solute in liquid chromatography

This review highlights the use of linear solvation energy relationships (LSERs) to evaluate liquid chromatography systems. From the systems investigated, this paper discusses the descriptors of solutes and the coefficients of various descriptors in detail. Descriptors, such as the solute size, polarity/polarizability, hydrogen bond acidity, and hydrogen bond basicity, in the LSER were examined. The effects of the stationary phase and mobile phase properties on the coefficients of these descriptors were reviewed. The LSER coefficients were evaluated in terms of the corresponding properties of the stationary phase and mobile phase. Copyright © 2012 John Wiley & Sons, Ltd.