Retention Mechanism of Weak Polar Solutes in Reversed Phase Liquid Chromatography

Guillaume, Yves Claude; Guinchard, C.

doi:10.1021/ac960141c

Cited by 46 publications

(45 citation statements)

References 28 publications

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“…Enthalpy-entropy compensation revealed that the retention of the imidazole derivatives was most affected by solute complexation in the mobile phase and less by interaction with the stationary phase. This result is substantiated by the general observation that the main factor affecting retention in RPLC is the distribution of the solute in the hydroorganic clusters in the mobile phase [17,18], whereas interactions in the stationary phase play a minor role. This suggest general rules that might be of use in understanding solute retention mechanisms.…”

Section: Resultsmentioning

confidence: 70%

Peculiarities of the mechanism of retention of imidazole derivatives when using hydroxypropyl-β-cyclodextrin as mobile phase additive

Peyrin

Guillaume

1999

Chromatographia

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SummaryTwo different methods have been used to investigate the retention mechanism of a series of imidazole derivatives in reversed-phase liquid chromatography (RPLC) over a range of column temperatures and with different concentrations of hydroxypropyl-fl-cyclodextrin (HPfl-CD) in the mobile phase. The first approach was the separate study of each factor affecting the retention mechanism; the second method was the simultaneous variation of all these factors. Changes in Van't Hoff plots as a function of HP-fl-CD concentration were examined. Enthalpy and entropy were determined for two physicochemical processes: (i) solute transfer from the mobile phase to the stationary phase, and (ii) solute complexation by HP-fl-CD. These thermodynamic data showed that the mechanism of retention of the solute was dependent on the concentration of HP-fl-CD in the mobile phase. For a HP-fl-CD concentration, C, greater than to 4 mM, from 28 ~ to a critical temperature, T*, solute retention was entropy-dominated because of inclusion of the solute in the HP-fl-CD cavity. Above T* retention was enthalpy-dominated, because of interaction of the solute with the RP18 stationary phase. At first 7-* increased as C was increased up to a critical value, C**; it then remained relatively constant because of auto-association of the HP-fl-CD molecules in the mobile phase. Enthalpy-entropy compensation revealed that HP-fl-CD-solute complexation had a greater effect on retention than RP18 stationary phasesolute interaction. This confirms that the main parameter determining retention in RPLC is the distribution of the solute in the mobile phase, and that interactions with the stationary phase play a minor role.

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Section: Resultsmentioning

confidence: 70%

Peculiarities of the mechanism of retention of imidazole derivatives when using hydroxypropyl-β-cyclodextrin as mobile phase additive

Peyrin

Guillaume

1999

Chromatographia

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“…The different solvent structures between the MeCN/water and MeOH/water systems and the consequences have been well studied by a few research groups. 4,19,[21][22][23][24][25][26] Their conclusions in such studies seem to be useful to explain our results, too.…”

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confidence: 94%

“…On the other hand, formation of water-acetonitrile interaction may not be favored compared to maintaining water-water and acetonitrileacetonitrile interactions. 4,19,[23][24][25][26] Therefore water and acetonitrile molecules will tend to form clusters of single components in the mixture although water and acetonitrile are completely mixable at any ratio. Acetonitrile-enriched "microphases" persist in the mobile phase over a wide composition ranges at higher acetonitrile content.…”

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confidence: 99%

The Hydroxyl Group-Solvent and Carbonyl Group-Solvent Specific Interactions for Some Selected Solutes Including Positional Isomers in Acetonitrile/Water Mixed Solvents Monitored by HPLC

2002

Bulletin of the Korean Chemical Society

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We have evaluated the specific hydroxyl group-solvent and carbonyl group-solvent interactions by using an Alltima C18 stationary phase and by measuring the retention data of carefully selected solutes in 60/40, 70/30, and 80/20(v/v%) acetonitrile/water eluents at 25, 30, 35, 40, 45, and 50 o C. The selected solutes are phenol, acetophenone, alkylbenznes(benzene to hexylbenznene), 4 positional isomers of phenylbutanol, 5-phenyl-1-pentanol, 3 positional isomers of alkylarylketone derived from butylbenzene, and 1-phenyl-2-hexanone. The magnitudes of hydroxyl group-acetonitrile/water specific interaction enthalpies are larger than those of carbonyl group-acetonitrile/water specific interaction enthalpies in general while the magnitudes of carbonyl group-methanol/water specific interaction enthalpies are larger than those of hydroxyl group-methanol/water specific interactions. We observed clear discrepancies in functional group-solvent specific interaction among positional isomers. The variation trends of solute transfer enthalpies and entropies with mobile phase composition in the acetonitrile/water system are much different from those in the methanol/water system. The well-known pocket formation of acetonitrile in aqueous acetonitrile mixtures has proven to be useful to explain such phenomena.

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“…It is known that linear relationships of the medium-property type specific to the primary chromatographic charac teristics often mask the mechanism of processes that occur at the interface and in the bulk solution. [18][19][20][21][22][23] In addition, relationships between the values of changes in enthalpy and entropy of adsorption from solutions pro vide 14-16 important information. These relationships are defined as enthalpy-entropy compensation or thermo dynamic compensation effect.…”

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confidence: 99%

“…[26][27][28][29] A relation ship between the changes in the enthalpy and entropy is frequently observed in a series of closely related physico chemical processes, 30 a series of substances with similar structure, 31 or chemical reactions proceeding via the same mechanism. 32 In processes of liquid phase adsorption and HPLC, as a rule to study the dependence of the TCA on the solution composition 18, 19 a constant composition of the solution is used or the compensation effect in a series of adsor bates. 14- 16 Therefore, an interrelation of the regularities of the medium-property type and compensation effect has not been elucidated so far.…”

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confidence: 99%

Medium-property relationships and compensation effect in the adsorption of heteroaromatic compounds from aqueous acetonitrile solutions

Saifutdinov

2014

Russ Chem Bull

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The thermodynamics of the adsorption of heteroaromatic compounds of the 1,3,4 oxadi azole and 1,2,4,5 tetrazine series from aqueous acetonitrile solutions was studied in Henry´s region under the conditions close to equilibrium using the dynamic method. The applicability of the adsorption retention models to the description of medium-property relationships at different temperatures was evaluated. The effect of the composition of the solution on the thermodynamic characteristics of adsorption was studied. The effect of the acetonitrile concen tration on the enthalpy and entropy of adsorption cannot be described by simple plots, since it is determined by the nature of the adsorbate. At the same time, the Gibbs free energy change of adsorption is characterized by a monotonic dependence on the acetonitrile concentration. Linear relationships between changes in the enthalpy and entropy of adsorption of the same substance from water-acetonitrile media of different compositions were established. The char acter of these relationships is determined by the adsorbate nature and explains the dependence of its thermodynamic characteristics of adsorption on the solution composition. The compen sation of the values of enthalpy and entropy changes in a series of the studied adsorbates measured for the constant composition of the solution was discovered. The concentration of acetonitrile significantly affects the character of this compensation.High performance liquid chromatography (HPLC) enjoys wide use today in both the practical analytical chemistry and physicochemical studies aimed at investi gating the chemistry of adsorbent surface and processes at interfaces. 1-3 Success in the separation of mixtures of compounds was achieved due to the application of highly selective adsorbents as stationary phases for HPLC. Among these are chemically modified silicas, porous graphitic carbon, hypercrosslinked polystyrenes, and metal organic frameworks. 4-12 A further development of analytical pos sibilities of HPLC and physicochemical foundations of its application for study of adsorption equilibrium in solu tions is impossible without the progress in the theory of adsorption selectivity found in liquid phase adsorption in Henry´s region. It is also necessary to understand how the structure and properties of all components of a complicat ed heterogeneous system solution-solid affect the ther modynamic characteristics of adsorption (TCA) from so lutions. 13- 16 It is known that among the most important parameters determining the values of TCA from solutions are the com position of the liquid phase and nature of its components. 13 Many works were published in which the influence of the mobile phase composition on retention in HPLC at the same temperature of the column was studied. 1,17 At the same time, the knowledge of dependence of the TCA on the solution composition is needed to predict the position of the adsorption equilibrium and to control adsorption selectivity under variable experimental conditions. It is known that linear relation...

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Retention Mechanism of Weak Polar Solutes in Reversed Phase Liquid Chromatography

Cited by 46 publications

References 28 publications

Peculiarities of the mechanism of retention of imidazole derivatives when using hydroxypropyl-β-cyclodextrin as mobile phase additive

Peculiarities of the mechanism of retention of imidazole derivatives when using hydroxypropyl-β-cyclodextrin as mobile phase additive

The Hydroxyl Group-Solvent and Carbonyl Group-Solvent Specific Interactions for Some Selected Solutes Including Positional Isomers in Acetonitrile/Water Mixed Solvents Monitored by HPLC

Medium-property relationships and compensation effect in the adsorption of heteroaromatic compounds from aqueous acetonitrile solutions

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