Comparison of the adsorption equilibrium of a few low-molecular mass compounds on a monolithic and a packed column in reversed-phase liquid chromatography

Gritti, Fabrice; Pia̧tkowski, Wojciech; Guiochon, Georges

doi:10.1016/s0021-9673(02)01279-7

Cited by 114 publications

(66 citation statements)

References 49 publications

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“…Two solutes producing such profiles are the alkyl aromatics, butyl and amyl benzene [6,41]. As observed elsewhere [2], we find it unsurprising that the aromatics benzene [2], naphthalene [2], and nbz produce such peaks in MEKC with SDS, given the correlation of retention in RPLC and MEKC with SDS.…”

Section: Origin Of Diffuse Fronts and Sharp Rears Of Peaks In Mekcsupporting

confidence: 69%

“…curved noses) observed at high c s . To our knowledge, this is the first report of a successfully modeled aquiline profile in MEKC, although such profiles occur in RPLC [6,11,12]. Based on hypothetical variations of R versus c we have studied, the aquiline profile arises from the nonlinear concave downward decrease of R with c shown later; in contrast, linear decreases of R with c produce anti-Langmuirian profiles.…”

Section: Isothermsmentioning

confidence: 88%

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Origin of peak asymmetry and isotherm nonlinearity in micellar electrokinetic chromatography: Variation of peak shape with buffer concentration

Williamson¹,

Davis²

2006

Electrophoresis

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The diffuse fronts and sharp rears of peaks of nitrobenzene (nbz) solubilized at high concentrations in 50 mM SDS and 2.5, 25, and 50 mM sodium tetraborate buffers were modeled in MEKC by measurements of, and fits to, concave upward isotherms, and by numerical solution of the continuity equation. The isotherms varied with buffer concentration, with the smallest limiting slope and largest curvature found for the 50 mM tetraborate buffer. The Brunauer, Emmett, and Teller isotherm described the peak profiles in all buffers, with symmetrical peaks observed at sub- and low-mM levels of nbz, anti-Langmuirian peaks observed at 10-20 mM levels, and aquiline peaks resembling curved noses observed at 20-30 mM levels. The variation of the partition coefficient with nbz and buffer concentrations was shown to result from nonideal thermodynamics. High-buffer concentrations salt out nbz from the mobile phase, as quantified by a mobile-phase activity coefficient related to the Setchenov constant of nbz in sodium tetraborate. The activity coefficient of nbz in SDS micelles was shown to resemble that measured by other researchers for benzene in micelles of sodium octyl sulfate, i.e. it decreases with increasing solute concentration and increases with electrolyte concentration. Many examples from the literature are discussed, in which the variation of the intramicellar activity coefficient with solute mole fraction is consistent with peaks having diffuse fronts and sharp rears.

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Section: Origin Of Diffuse Fronts and Sharp Rears Of Peaks In Mekcsupporting

confidence: 69%

Section: Isothermsmentioning

confidence: 88%

Origin of peak asymmetry and isotherm nonlinearity in micellar electrokinetic chromatography: Variation of peak shape with buffer concentration

Williamson¹,

Davis²

2006

Electrophoresis

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“…Here, coefficient b has clear physical meaning. In contrast, both the isotherm and b have limited meaning in condensed media [25,26]. With increasing analyte concentration, analyte is preferentially solubilized by analyterich micelles, instead of analyte-free ones.…”

Section: Isothermmentioning

confidence: 99%

Modeling of anti-Langmuirian peaks in micellar electrokinetic chromatography: Benzene and naphthalene

Williamson¹,

Davis²

2005

Electrophoresis

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Peaks of benzene (bz) and naphthalene (np) having diffuse fronts and steep rears under overload conditions were studied quantitatively in MEKC with SDS surfactant. The retardation factors of these compounds, solubilized at microM to mM concentrations by either 10, 30, or 50 mM SDS, were determined by vacancy MEKC and frontal analysis MEKC. Isotherm coordinates were calculated from the retardation factors, and the equation for the concave upward anti-Langmuir isotherm was fit to them. Peak profiles were computed with the MacCormack algorithm from the isotherm fits and a simplified continuity equation appropriate to MEKC. These profiles were compared to ones generated in normal MEKC from samples of bz and np solubilized at muM to mM concentrations by either 10, 30, or 50 mM SDS. In all cases, the anti-Langmuir isotherm described the asymmetry of experimental peaks. For bz in 30 and 50 mM SDS and np in 10 and 50 mM SDS, good to excellent agreement was found between the experimental and predicted profiles. For bz in 10 mM SDS, the experimental profiles were more broadened than the predicted ones, although their asymmetries agreed. For np in 30 mM SDS, the experimental isotherm predicted greater peak asymmetry than was observed, and the correct anti-Langmuir isotherm for all sample concentrations and field strengths was calculated from the most asymmetrical peak by the inverse method. The relative decrease of zone velocity with increasing analyte concentration was calculated from the isotherm parameters, electrokinetic mobilities, retardation factors, surfactant concentrations, and CMC. The simplification of the continuity equation was justified.

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“…The porous polymer-based monoliths were proved excellent for the rapid separation of large molecules [7][8][9][10][11] and the porous silica-based monoliths were very suitable for the fast separation of small molecules. [12][13][14][15] Several recent reviews describing the preparation and application of monoliths have been published. [16][17][18][19][20][21] The most common polymer-based monolithic columns were prepared by in-situ polymerization of organic monomers in suitable pore-forming solvents within capillary tubes.…”

Section: Introductionmentioning

confidence: 99%

Rapid Separation of Proteins by Capillary HPLC on a Short Polymethacrylate‐based Strong Cation‐exchange Monolithic Column

2010

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A polymethacrylate-based strong cation-exchange capillary monolithic column was prepared by in-situ copolymerization for the fast separation of proteins. Glycidyl methacrylate (GMA) was used as monomer, ethylenedimethacrylate (EDMA) as cross link agent and the mixture of 1-propanol, 1,4-butanediol and water as porogen solvent. The monolith was sulfonated using 1 mol/L Na 2 SO 3 based on a ring opening of epoxides. The influences of the contents of the porogen solvent and GMA and the various concentration ratios of 1-propanol to 1,4-butanediol in the polymerization mixture on the morphology, porosity, globule size, stability and column efficiency were investigated. The morphology and pore size distribution of the monolith were characterized by SEM and mercury intrusion porosimetry, respectively. Using only 1.5 cm length of this monolithic capillary column, four kinds of proteins, trypsin, cytochrome C, lysozyme (egg white) and egg albumin, were successfully separated from each other in 5 min at a high flow rate of 110 mm/s.

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Comparison of the adsorption equilibrium of a few low-molecular mass compounds on a monolithic and a packed column in reversed-phase liquid chromatography

Cited by 114 publications

References 49 publications

Origin of peak asymmetry and isotherm nonlinearity in micellar electrokinetic chromatography: Variation of peak shape with buffer concentration

Origin of peak asymmetry and isotherm nonlinearity in micellar electrokinetic chromatography: Variation of peak shape with buffer concentration

Modeling of anti-Langmuirian peaks in micellar electrokinetic chromatography: Benzene and naphthalene

Rapid Separation of Proteins by Capillary HPLC on a Short Polymethacrylate‐based Strong Cation‐exchange Monolithic Column

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