Observed Partition Coefficients Research Articles

Abraham model correlations for describing the partition of organic compounds from water into the methyl ethyl ketone extraction solvent

ABSTRACT Experimental water-to-methyl ethyl ketone partition coefficients have been determined for 34 different organic solutes at ambient room temperature based on gas–liquid chromatographic measurements. Updated Abraham model correlations were determined for describing solute transfer into methyl ethyl ketone by combining the measured partition coefficient data determined in the present study with published experimental values taken from chemical and engineering literature. Experimental data for 48 compounds were used in determining the revised Abraham model correlations. The revised mathematical correlations were determined to back-calculate the observed partition coefficient data to within an overall average standard deviation of 0.17 log units or less. The partitioning characteristics of the water-to-methyl ethyl ketone system are compared to the characteristics of two other biphasic water-to-ketone partitioning systems.

Development of Abraham model correlations for short-chain glycol-grafted imidazolium and pyridinium ionic liquids from inverse gas-chromatographic measurements

Infinite dilution activity coefficients and gas-to-liquid partition coefficients are herein reported for more than 45 organic solutes of varying polarity and hydrogen-bonding character dissolved within the ether-grafted ionic liquids 1-ethyl-3-(2-methoxyethyl)imidazolium bis(trifluoromethylsulfonyl)imide and N-(2-methoxyethyl)pyridinium bis(trifluoromethylsulfonyl)imide. Experimental values were determined in 10 K intervals from 323.15 to 373.15 K using the method of inverse gas chromatography. Measured infinite dilution activity coefficients were then used to determine the partial molar excess Gibbs free energies, enthalpies, and entropies associated with the dissolution of these model solutes into these two short-chain glycol-grafted ionic liquids. Finally, based on the measured infinite dilution activity coefficient data, Abraham model correlations have been established for solute transfer into these ionic liquids, including the calculation of cation-specific equation coefficients. The derived Abraham model correlations were found to back-calculate the observed partition coefficients to within 0.09 to 0.13 log units.

Abraham solvation parameter model: calculation of ion-specific equation coefficients for the N-Ethyl-N-methylmorpholinium and N-Octyl-N-methylmorpholinium cations

ABSTRACT Abraham model correlations are derived for describing gas-to-ionic liquid and water-to-ionic liquid partition coefficients from published experimental data for solutes dissolved in both N-ethyl-N-methylmorpholinium bis(trifluoromethylsulfonyl)imide and N-octyl-N-methylmorpholinium bis(trifluoromethylsulfonyl)imide. Derived Abraham model correlations describe the observed partition coefficient data to within 0.14 log units. As part of the current study, we also determined Abraham model ion-specific equation coefficients for both N-ethyl-N-methylmorpholinium and N-octyl-N-methylmorpholinium cations.

Characterization of the solubilizing ability of tetraalkylammonium ionic liquids containing a pendant alkyl chain bearing a basic N,N-dimethylamino or N,N-dimethylaminoethoxy functionality

Infinite dilution activity coefficients and gas-to-ionic liquid partition coefficients are reported for >40 different organic compounds dissolved in N-[2-(N′,N′-dimethylamino)ethyl]-N,N-(dimethyl)-1-propanaminium bis(trifluoromethylsufonyl)imide, N-[2-(N′,N′-dimethyl-amino)ethyl]-N,N-(dimethyl)-1-butanaminium bis(trifluoromethylsufonyl)imide, N-[2-(N′,N′-dimethylamino)ethoxyethyl]-N,N-(dimethyl)-1-propanaminium bis(trifluoromethylsufonyl)imide, and N-[2-(N′,N′-dimethylamino)ethoxyethyl]-N,N-(dimethyl)-1-butanaminium bis(trifluoromethylsufonyl)imide in the temperature range from 323.15K to 373.15K. Partial molar excess enthalpies and partial molar excess entropies of solution were calculated from the temperature dependence of the infinite dilution activity coefficient assuming a van't Hoff relationship. Abraham model ionic liquid-specific correlations were determined from the measured partition coefficients. The derived mathematical expressions described the observed partition coefficients to within a standard deviation of 0.14 log units (or less).

Development of Abraham model IL-specific correlations for N-triethyl(octyl)ammonium bis(fluorosulfonyl)imide and 1-butyl-3-methylpyrrolidinium bis(fluorosulfonyl)imide

ABSTRACTAbraham model correlations are derived for describing gas-to-ionic liquid and water-to-ionic liquid partition coefficients from published experimental data for solutes dissolved in both N-triethyl(octyl)ammonium bis(fluorosulfonyl)imide and 1-butyl-3-methyl-pyrrolidinium bis(fluorosulfonyl)imide. Derived Abraham model correlations describe the observed partition coefficient data to within 0.13 log units. As part of the current study the existing equation coefficients for the N-triethyl(octyl)ammonium cation were updated and reported for the first time were equation coefficients for the bis(trifluorosulfonyl)imide anion.

Infinite dilution activity coefficients and gas-to-liquid partition coefficients of organic solutes dissolved in 1-sec-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and in 1-tert-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

ABSTRACTInverse gas chromatography was used to measure infinite dilution activity coefficients and gas-to-liquid partition coefficients for 48 organic solute probes in either 1-sec-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or 1-tert-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide in the temperature range from 323.15 to 373.15 K. Partial molar excess enthalpies of solution were calculated from the variation of the infinite dilution activity coefficients with temperature. Abraham model correlations were also derived from the experimental partition coefficient data. The derived Abraham model correlations describe the observed partition coefficients to within 0.11 log units.

Infinite Dilution Activity Coefficients and Gas-to-Liquid Partition Coefficients of Organic Solutes Dissolved in 1-Benzylpyridinium Bis(Trifluoromethylsulfonyl)Imide and 1-Cyclohexylmethyl-1-Methylpyrrolidinium Bis(Trifluoromethylsulfonyl)Imide

Infinite dilution activity coefficients and gas-to-ionic liquid partition coefficients were measured for a chemically diverse set of 48 or more organic solute probes dissolved in the ionic liquids 1-benzylpyridinium bis(trifluoromethylsulfonyl)imide ([BzPy][Tf2N]) and 1-cyclohexylmethyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([ChxmPyrr][Tf2N]) in the temperature range from 323.15 to 373.15 K using inverse gas chromatography. Selectivities and capacities for different separation problems were calculated from the measured chromatographic data. The measured partition coefficients were correlated using mathematical equations based on the Abraham general solvation parameter model. The derived Abraham model correlations back-calculated the observed partition coefficients to within 0.12 log10 units.

Abraham Model Correlations for Triethylene Glycol Solvent Derived from Infinite Dilution Activity Coefficient, Partition Coefficient and Solubility Data Measured at 298.15 K

A gas chromatographic headspace analysis method was used to experimentally determine gas-to-liquid partition coefficients and infinite dilution activity coefficients for 29 liquid organic solutes dissolved in triethylene glycol at 298.15 K. Solubilities were also determined at 298.15 K for 23 crystalline nonelectrolyte organic compounds in triethylene glycol based on spectroscopic absorbance measurements. The experimental results of the headspace chromatographic and spectroscopic solubility measurements were converted to gas-to-triethylene glycol and water-to-triethylene glycol partition coefficients, and molar solubility ratios using standard thermodynamic relationships. Expressions were derived for solute transfer into triethylene glycol by combining our measured experimental values with published literature data. Mathematical correlations based on the Abraham model describe the observed partition coefficient and solubility data to within 0.16 log10 units (or less).

Development of Abraham model correlations for describing the transfer of molecular solutes into propanenitrile and butanenitrile from water and from the gas phase

ABSTRACTExperimental solubilities were measured for 20 crystalline organic solutes dissolved in propanenitrile and for 13 crystalline organic solutes dissolved in butanenitrile at 298.15 K. Infinite dilution activity coefficient data for solutes dissolved in propanenitrile and butanenitrile have been compiled from the published chemical and engineering literature and converted into gas-to-liquid partition coefficients and water-to-organic solvent partition coefficients through standard thermodynamic relationships. Abraham model correlations were developed for describing solute transfer into both propanenitrile and butanenitrile by combining our measured solubility data with the partition coefficients that we calculated from the published activity coefficient data. The derived Abraham model correlations were found to back-calculate the observed partition coefficients and molar solubility data to within 0.14 log units.

Abraham Model Expressions for Describing Water-to-Diethylene Glycol and Gas-to-Diethylene Glycol Solute Transfer Processes at 298.15 K

A gas chromatographic headspace analysis method was used to experimentally determine gas-to-liquid partition coefficients and infinite dilution activity dilution for 14 different aliphatic and cyclic hydrocarbons (alkanes, cycloalkanes, alkenes, alkynes), eight different aromatic compounds (benzene, alkylbenzenes, halobenzenes), five different chloroalkanes (dichloromethane, trichloromethane, 1-chlorobutane, 1,2-dichloropropane, isopropylbromide), tetrahydrofuran, butyl acetate, and acetonitrile dissolved in diethylene glycol at 298.15 K. Solubilities were also measured at 298.15 K for 31 crystalline nonelectrolyte organic solutes including several polycyclic aromatic hydrocarbons and substituted benzoic acid derivatives. The experimental results of the headspace chromatographic and spectroscopic solubility measurements were converted to gas-to-diethylene glycol and water-to-diethylene glycol partition coefficients, and molar solubility ratios using standard thermodynamic relationships. Expressions were derived for solute transfer into diethylene glycol from the calculated partition coefficients and solubility ratios. Mathematical correlations based on the Abraham model describe the observed partition coefficient and solubility data to within 0.14 log10 units (or less).

Influence of the natural colloids on the multi-phase distributions of antibiotics in the surface water from the largest lake in North China

Understanding antibiotic adsorption on natural colloids is crucial for prediction of the behavior, bioavailability and toxicity of antibiotics in natural waters. In the present study, the filtered water (dissolved phase, <0.7μm) was further separated into colloidal phase (1kDa-0.7μm) and soluble phase (<1kDa) by cross-flow ultrafiltration (CFUF), and the spatial-temporal variation and distribution of six antibiotics in multi-phases were investigated in Baiyangdian Lake. Results indicated that antibiotic concentrations differed significantly with sampling location and time. The mean concentrations of antibiotics ranged between 13.65 and 320.44ngL−1 in the dissolved phase, and the colloidal phase accounted for 4.7–49.8% of all antibiotics, suggesting that natural colloids play an important role as carriers of antibiotics in aquatic environments. Because of the influence of colloids, the partition coefficients of antibiotics between suspended particulate matter (SPM) and soluble phase (intrinsic partition coefficients, Kpint) were found to be 6.18–109.60% higher than corresponding observed partition coefficients (Kpobs, between SPM and dissolved phase). The mean partition coefficients between colloidal and soluble phase (Kcol.) ranged between 6218 and 117,374Lkg−1, which were 1–2 orders of magnitude greater than Kpint values. In order to explore the adsorption mechanism of antibiotics on colloids, Pearson's correlations were performed. The results showed that log Kcol. were negatively correlated with cations in natural colloids; especially with Mg (r, −0.643, P<0.01) for oxytetracycline (OTC), and with both Ca (−0.595, P<0.01) and Mg (−0.593, P<0.01) in the case of ofloxacin (OFL). This result revealed that the competitive effect between cations and antibiotics was the main factor influencing the adsorption behavior of antibiotics on natural colloids in the lake.

Ion-specific equation coefficient version of the Abraham model for ionic liquid solvents: determination of coefficients for tributylethylphosphonium, 1-butyl-1-methylmorpholinium, 1-allyl-3-methylimidazolium and octyltriethylammonium cations

ABSTRACTGas-to-ionic liquid partition coefficient data have been assembled from the published chemical literature for solutes dissolved in 1-allyl-3-methylimidazolium dicyanamide, 1-allyl-3-methylimidazolium bis(trifluoromethylsulphonyl)imide, octyltriethylammonium bis(trifluomethyl-sulphonyl)imide, tributylethylphosphonium diethylphosphate and 1-butyl-1-methylmorpholinium tricyanomethanide. The published experimental data were converted to water-to-ionic liquid partition coefficients using standard thermodynamic relationships. Both sets of partition coefficients were correlated with the Abraham solvation parameter model. The derived Abraham model correlations described the observed partition coefficient data to within 0.13 log units. Cation-specific equation coefficients were calculated for each of the cations present in the five ionic liquid solvents studied. The calculated cation-specific equation coefficients can be combined with previously reported ion-specific equation coefficients for 19 different anions to yield Abraham model correlations for predicting the partitioning the behaviour of solutes in 76 different anhydrous ionic liquid solvents.

Abraham model correlations for describing solute transfer into 2-butoxyethanol from both water and the gas phase at 298 K

Infinite dilution activity coefficients (γ∞) were measured at 298K for 12 different aliphatic hydrocarbons (alkanes, cycloalkanes, alkenes), 11 different aromatic compounds (benzene, alkylbenzenes, halobenzenes, naphthalene), and 2-chloro-2-methylpropane dissolved in 2-butoxyethanol at 298K using a headspace gas chromatographic method. As part of the experimental study solubilities of 19 crystalline nonelectrolyte solutes (2-hydroxybenzoic acid, acetylsalicylic acid, 3,5-dinitro-2-methylbenzoic acid, acenaphthene, trans-stilbene, xanthene, phenothiazine, 3,5-dinitrobenzoic acid, 3-chlorobenzoic acid, 2-methylbenzoic acid, 4-chloro-3-nitrobenzoic acid, 2-chloro-5-nitrobenzoic acid, benzoic acid, 4-aminobenzoic acid, benzil, thioxanthen-9-one, 3-nitrobenzoic acid, fluoranthene, and diphenyl sulfone) were determined in 2-butoxyethanol at 298K using a static, spectrophotometric method. The experimental values were converted to gas-to-2-butoxyethanol and water-to-2-butoxyethanol partition coefficients, and molar solubility ratios using standard thermodynamic relationships. Abraham model correlations for solute transfer into 2-butoxyethanol were derived from the calculated partition coefficients and solubility ratios. The derived Abraham model describes the observed partition coefficient and solubility data to within 0.14logunits (or less).

Comment on "structural determinants of drug partitioning in surrogates of phosphatidylcholine bilayer strata".

The Abraham model correlation for describing the partitioning behavior of solutes between water and hexadecane was redetermined using the measured partition coefficient data and solute descriptors derived from experimental data. The newly derived correlation provides a much better mathematical description of the observed partition coefficient data than the correlation given in the published paper.

Separation of 1,3-Propanediol from Aqueous Solutions by Ion Exchange Chromatography

Abstract 1,3-propanediol is a promising monomer with many applications and can be produced by bioconversion of renewable resources. The separation of this product from fermentation broth is a difficult task. In this work, the application of cation exchange resin for the separation of 1,3-propanediol from model aqueous solution was examined. The best effect of separation of 1,3-propanediol from glycerol using sorption method was obtained for H+ resin form, although the observed partition coefficient of 1,3-propanediol was low. On the basis of the results of the sorption of 1,3-propanediol, the ionic forms of the resin were selected and used in the next experiments (H+, Ca2+, Ag+, Na+, Pb2+, Zn2+). The best results in ion exchange chromatography were obtained for cation exchange resin in H+ and Ca2+ form. The use of smaller particle size of resin and a longer length of the column allows to obtain better separation of mixtures.

Partition-Diffusion Model for Enantioseparation of Phenylalanine Using Hollow Fiber SLM

This paper deals with the partittion-diffusion model of transport and enantioseparation of phenylalanine across hollow fiber supported liquid membranes. Observed partition coefficient between the feed phase and the membrane phase, the stripping phase and the membrane phase, mass transfer resistance of boundary layer in strip phase inside the hollow fibers, boundary layer in feed phase and the diffusion in the membrane phase are taken into account in the model equations.

Partition Coefficients of Organic Contaminants with Carbohydrates

In view of the current lack of reliable partition coefficients for organic compounds with carbohydrates (K(ch)), carefully measured values with cellulose and starch, the two major forms of carbohydrates, are provided for a wide range of compounds: short-chain chlorinated hydrocarbons, halogenated benzenes, alkyl benzenes, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and organochlorine pesticides. To ensure the accuracy of the K(ch) data, solute concentrations in both water and carbohydrate phases are measured by direct solvent extraction of the samples. For a given compound, the observed partition coefficient with cellulose (K(cl)) is virtually the same as that with starch (K(st)). This finding expedites the evaluation of organic contamination with different forms of carbohydrates. The presently determined K(ch) values of 13 PAHs are substantially lower (by 3-66 times) than the literature data; the latter are suspect as they were obtained with (i) presumably impure carbohydrate samples or (ii) indirectly measured equilibrium solute concentrations in carbohydrate and water phases. Although the K(ch) values are generally considerably lower than the respective K(ow) (octanol-water) or K(lipid) (lipid-water), accurate K(ch) data are duly required to accurately estimate the contamination of carbohydrates by organic compounds because of the abundance of carbohydrates over lipids in crops and plants. To overcome the current lack of reliable K(ch) data for organic compounds, a close correlation of log K(ch) with log K(ow) has been established for predicting the unavailable K(ch) data for low-polarity compounds.

Colloids as a sink for certain pharmaceuticals in the aquatic environment

The occurrence and fate of pharmaceuticals in the aquatic environment is recognized as one of the emerging issues in environmental chemistry and as a matter of public concern. Existing data tend to focus on the concentrations of pharmaceuticals in the aqueous phase, with limited studies on their concentrations in particulate phase such as sediments. Furthermore, current water quality monitoring does not differentiate between soluble and colloidal phases in water samples, hindering our understanding of the bioavailability and bioaccumulation of pharmaceuticals in aquatic organisms. In this study, an investigation was conducted into the concentrations and phase association (soluble, colloidal, suspended particulate matter or SPM) of selected pharmaceuticals (propranolol, sulfamethoxazole, meberverine, thioridazine, carbamazepine, tamoxifen, indomethacine, diclofenac, and meclofenamic acid) in river water, effluents from sewage treatment works (STW), and groundwater in the UK. The occurrence and phase association of selected pharmaceuticals propranolol, sulfamethoxazole, meberverine, thioridazine, carbamazepine, tamoxifen, indomethacine, diclofenac, and meclofenamic acid in contrasting aquatic environments (river, sewage effluent, and groundwater) were studied. Colloids were isolated by cross-flow ultrafiltration (CFUF). Water samples were extracted by solid-phase extraction (SPE), while SPM was extracted by microwave. All sample extracts were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the multiple reaction monitoring. Five compounds propranolol, sulfamethoxazole, carbamazepine, indomethacine, and diclofenac were detected in all samples, with carbamazepine showing the highest concentrations in all phases. The highest concentrations of these compounds were detected in STW effluents, confirming STW as a key source of these compounds in the aquatic environments. The calculation of partition coefficients of pharmaceuticals between SPM and filtrate (observed partition coefficients, Kobsp, Kobsoc), between SPM and soluble phase (intrinsic partition coefficients, Kintp, Kintoc), and between colloids and soluble phase (Kcoc) showed that intrinsic partition coefficients (Kintp, Kintoc) are between 25% and 96%, and between 18% and 82% higher than relevant observed partition coefficients values, and are much less variable. Secondly, Kcoc values are 3-4 orders of magnitude greater than Kintoc values, indicating that aquatic colloids are substantially more powerful sorbents for accumulating pharmaceuticals than sediments. Furthermore, mass balance calculations of pharmaceutical concentrations demonstrate that between 23% and 70% of propranolol, 17-62% of sulfamethoxazole, 7-58% of carbamazepine, 19-84% of indomethacine, and 9-74% of diclofenac are present in the colloidal phase. The results provide direct evidence that sorption to colloids provides an important sink for the pharmaceuticals in the aquatic environment. Such strong pharmaceutical/colloid interactions may provide a long-term storage of pharmaceuticals, hence, increasing their persistence while reducing their bioavailability in the environment. Pharmaceutical compounds have been detected not only in the aqueous phase but also in suspended particles; it is important, therefore, to have a holistic approach in future environmental fate investigation of pharmaceuticals. For example, more research is needed to assess the storage and long-term record of pharmaceutical residues in aquatic sediments by which benthic organisms will be most affected. Aquatic colloids have been shown to account for the accumulation of major fractions of total pharmaceutical concentrations in the aquatic environment, demonstrating unequivocally the importance of aquatic colloids as a sink for such residues in the aquatic systems. As aquatic colloids are abundant, ubiquitous, and highly powerful sorbents, they are expected to influence the bioavailability and bioaccumulation of such chemicals by aquatic organisms. It is therefore critical for colloids to be incorporated into water quality models for prediction and risk assessment purposes.

Characterization of the Partitioning of Gaseous Solutes Into Humic Acid with the Abraham Model and Temperature‐Independent Equation Coefficients

AbstractPublished gas‐to‐Leonardite humic acid partition coefficient data, measured at a relative humidity of 98% and at 278.15, 288.15, 298.15, 308.15, and 318.15 K, were correlated with the Abraham solvation parameter model. The five derived temperature‐specific correlations described the observed partition coefficient data to within an overall standard deviation of 0.33 log units. A method was devised for combining experimental partition coefficients measured at different temperatures into a single regression correlation. The proposed method described the 664 experimental partition coefficients, which covered the 278.15–348.15 K temperature interval, to within a standard deviation of 0.33 log units.

Enantioseparation of racemic alpha-cyclohexyl-mandelic acid across hollow fiber supported liquid membrane

This paper deals with the enantioseparation of racemic alpha-cyclohexyl-mandelic acid containing copper(II) N-dodecyl-(L)-hydroxyproline (CuN2) as a chiral carrier using hollow fiber supported liquid membrane. A mathematical model of transport and enantioseparation of chiral compounds was deduced, the observed partition coefficient between the feed phase and the membrane phase, the stripping phase and the membrane phase, mass transfer resistance of boundary layer in strip phase inside the hollow fibers, boundary layer in feed phase and the diffusion in the membrane phase are taken into account in the model equations. Using the experimental results, several parameters of the proposed model have been achieved by nonlinear fitting method. It is a simply mathematical model which can be easily used to predict the concentration of the enantiomers and the separation factor of the enantioseparation process, and it can also be used to design and scale up the enantioseparation process.