Application of capillary gas chromatography to studies on solvation thermodynamics

González, Francisco Rex

doi:10.1016/j.chroma.2003.11.024

Cited by 29 publications

(19 citation statements)

References 143 publications

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“…These last columns, however, have less acceptance among researchers for obtaining relevant physicochemical information [18,23,24]. The main argument against the capillary format is that some solvents would not form a uniform coating onto the silica walls, especially stationary phases having low viscosity and, even worse if they have high critical surface tension of wetting [24,25].…”

Section: Introductionmentioning

confidence: 99%

Determination of gas–liquid partition coefficients of several organic solutes in trihexyl(tetradecyl)phosphonium bromide using capillary gas chromatography columns

Ronco

Menestrina

Romero

et al. 2017

Journal of Chromatography A

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In this paper, we report gas-liquid partition constants for thirty-five volatile organic solutes in the room temperature ionic liquid trihexyl(tetradecyl)phosphonium bromide measured by gas-liquid chromatography using capillary columns. The relative contribution of gas-liquid partition and interfacial adsorption to retention was evaluated through the use of columns with different the phase ratio. Four capillary columns with exactly known phase ratios were constructed and employed to measure the solute retention factors at four temperatures between 313.15 and 343.15K. The partition coefficients were calculated from the slopes of the linear regression between solute retention factors and the reciprocal of phase ratio at a given temperature according to the gas-liquid chromatographic theory. Gas-liquid interfacial adsorption was detected for a few solutes and it has been considered for the calculations of partition coefficient. Reliable solute's infinite dilution activity coefficients can be obtained when retention data are determined by a unique partitioning mechanism. The partial molar excess enthalpies at infinite dilution have been estimated from the dependence of experimental values of solute activity coefficients with the column temperature. A thorough discussion of the uncertainties of the experimental measurements and the main advantages of the use of capillary columns to acquire the aforementioned relevant thermodynamic information was performed.

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Section: Introductionmentioning

confidence: 99%

Determination of gas–liquid partition coefficients of several organic solutes in trihexyl(tetradecyl)phosphonium bromide using capillary gas chromatography columns

Ronco

Menestrina

Romero

et al. 2017

Journal of Chromatography A

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“…4 Despite the advantages of WGC, PGC is still the dominant method in the γ ∞ determination, due to the difficulty in quantifying the very small values of SP amount and carrier gas flow rate in WGC. 5−10 Only a few published papers used WGC in γ ∞ determination, in which the carrier gas flow rates were generally measured by gas flow meter and might suffer from large errors.…”

mentioning

confidence: 99%

Accurate Measurements of Infinite Dilution Activity Coefficients Using Gas Chromatography with Static-Wall-Coated Open-Tubular Columns

Luo

et al. 2012

Anal. Chem.

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Wall-coated open-tubular (WCOT) columns provide higher column efficiency and lower solute interfacial adsorption effect than packed columns. However, previous efforts used to measure the infinite dilution activity coefficient (γ(∞)) via a chromatographic technique have used packed columns, because the low carrier gas flow rate (U) and the small stationary phase amount (n(2)) in WCOT columns raise large errors. By rationally revising the γ(∞)-calculation equation for static-wall-coated open-tubular column, we observed that U and n(2) are not necessarily needed and the resulting error could be reduced, and WCOT column gas chromatography subsequently became a superior method for the accurate γ(∞) determination. In this study, we validate our revised γ(∞)-calculation equation by measuring γ(∞) in an ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate system, in which 55 organic compounds covering a wide range of functional groups were used as probe solutes and their γ(∞) values in the ionic liquid were determined at 40.0, 50.0, and 60.0 °C. Experimental error analysis shows that our revised equation remarkably reduces the error compared to the common γ(∞)-calculation equation. Our data is consistent with previously reported values obtained via other techniques, which further proves the credibility of our revised equation. The accurately determined γ(∞) values can be directly used to calculate the partial molar excess enthalpy, selectivity, and capacity, which will benefit for the rapid screening of solvents (especially ionic liquids) in separation approaches.

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“…Este modelo de incremento de la retención R' descripto y ampliamente usado por Schurig y sus colaboradores permite calcular valores de constantes de partición evadiendo la determinación de la relación de fases [98]. Sin embargo, existen evidentes desventajas en el uso de esta aproximación:…”

Section: Modelo De Incremento De La Retención R'unclassified

“… Este procedimiento se basa en un soluto estándar B* cuya constante de partición se supone que no varía con la adición del selector enantiomérico al polisiloxano aquiral. Esta condición es muy difícil de alcanzar dado que, aun en el caso de una muy baja afinidad del estándar por el aditivo, la presencia del selector quiral modificará el volumen molar de la fase estacionaria y por lo tanto la constante de partición, K o de la sustancia de referencia [98].…”

Section: Modelo De Incremento De La Retención R'unclassified

“…Respecto de la relación de fases , se trata de un parámetro de la columna esencial (i) para comparar medidas realizadas sobre diferentes columnas, (ii) para estimar valores absolutos de a partir de la ecuación (1.31) y (iii) para la determinación de diferencias de entropía de transferencia de solutos. La dificultad aparente que conlleva el conocimiento preciso de en capilares de GC ha llevado, en algunos casos, a la evasión de su determinación directa [73,99,100] lo cual obliga a la utilización de distintas aproximaciones con niveles de precisión [101] tales que podrían enmascarar fenómenos de interés, por ejemplo, de solvatación [98,[102][103][104][105][106].…”

Section: Determinación De La Relación De Fasesunclassified

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Estudio de la complejación entre selectores quirales derivados de ciclodextrina y solutos con actividad óptica por cromatografía gaseosa en columnas capilares

Lebed¹

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Objetivo general Desarrollo de métodos separativos quirales para la enantioseparación de compuestos de distintas familias químicas por cromatografía gaseosa empleando columnas capilares que contienen sistemas mixtos formados por una matriz polimérica quiral a base de polisiloxanos en los que se disolvió un derivado de γ-ciclodextrina. Objetivos específicos - Preparación y desarrollo de capilares para cromatografía de gases conteniendo como fase estacionaria depositada una película uniforme de espesor conocido. Las fases que se prepararon contienen distintos porcentajes de octakis(3-O-butanoil-2,6-di-O-pentil)-γ-ciclodextrina disuelta en un polisiloxano de polaridad intermedia como OV-1701 (7% fenil-7% ciano-metilpolisiloxano). Los capilares de evaluaron cromatográficamente (medición de eficiencia de la columna y capacidad de enantioreconocimiento). Este derivado de ciclodextrina elegido es líquido a temperatura ambiente, por lo que se prepararon mezclas desde 0 hasta aproximadamente un 30% p/p de selector en el polisiloxano. - Determinación de las constantes de asociación absolutas entre el derivado de ciclodextrina y solutos ópticamente activos de diversas familias químicas en un rango de temperaturas determinado fundamentalmente por la presión de vapor del soluto estudiado - Evaluación de la contribución ejercida por la matriz aquiral sobre la retención cromatográfica total y sobre la enantioselectividad de las columnas. - Medición e interpretación de los parámetros termodinámicos involucrados en la enantioseparación a partir de la dependencia de las constantes de asociación soluto-selector con la temperatura. - Comparación de las constantes absolutas obtenidas a una dada temperatura con los valores que se obtendrían a partir del modelo de incremento de la retención a la misma temperatura. Evaluación crítica de los resultados.

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Application of capillary gas chromatography to studies on solvation thermodynamics

Cited by 29 publications

References 143 publications

Determination of gas–liquid partition coefficients of several organic solutes in trihexyl(tetradecyl)phosphonium bromide using capillary gas chromatography columns

Determination of gas–liquid partition coefficients of several organic solutes in trihexyl(tetradecyl)phosphonium bromide using capillary gas chromatography columns

Accurate Measurements of Infinite Dilution Activity Coefficients Using Gas Chromatography with Static-Wall-Coated Open-Tubular Columns

Estudio de la complejación entre selectores quirales derivados de ciclodextrina y solutos con actividad óptica por cromatografía gaseosa en columnas capilares

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