Search results for "Half-widths"

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Peak half-width plots to study the effect of organic solvents on the peak performance of basic drugs in micellar liquid chromatography.

2009

The addition of the anionic surfactant sodium dodecyl sulphate (SDS) to hydro-organic mixtures of methanol, ethanol, propanol or acetonitrile with water yielded enhanced peak shape (i.e. increased efficiencies and symmetrical peaks) for a group of basic drugs (β-blockers) chromatographed with a Kromasil C18 column. The effect can be explained by the thin layer of surfactant associated to the hydrocarbon chain on the stationary phase in the presence of the organic solvents, which covers the free silanols on the siliceous support avoiding their interaction with the cationic basic drugs. These instead interact with the anionic head of the surfactant increasing their retention and allowing a mo…

AcetonitrilesInorganic chemistryAdrenergic beta-AntagonistsBiochemistryMicelleAnalytical ChemistryPropanolchemistry.chemical_compoundPulmonary surfactantBasic compoundsSodium dodecyl sulphatePeak performanceSodium dodecyl sulfateAcetonitrileMicelleschemistry.chemical_classificationChromatographyOrganic ChemistrySodium Dodecyl SulfateGeneral MedicineOrganic solventsHydrocarbonchemistryMicellar liquid chromatographyAlcoholsLinear Modelsβ-BlockersMethanolMicellar liquid chromatographyPeak half-widthsChromatography LiquidJournal of chromatography. A
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Half-width plots, a simple tool to predict peak shape, reveal column kinetics and characterise chromatographic columns in liquid chromatography: Stat…

2013

Peak profiles in chromatography are characterised by their height, position, width and asymmetry; the two latter depend on the values of the left and right peak half-widths. Simple correlations have been found between the peak half-widths and the retention times. The representation of such correlations has been called half-width plots. For isocratic elution, the plots are parabolic, although often, the parabolas can be approximated to straight-lines. The plots can be obtained with the half-widths/retention time data for a set of solutes experiencing the same kinetics, eluted with a mobile phase at fixed or varying composition. When the analysed solutes experience different resistance to mas…

Peak profiles in chromatography are characterised by their height position width and asymmetry; the two latter depend on the values of the left and right peak half-widths. Simple correlations have been found between the peak half-widths and the retention times. The representation of such correlations has been called half-width plots. For isocratic elution the plots are parabolic although often the parabolas can be approximated to straight-lines. The plots can be obtained with the half-widths/retention time data for a set of solutes experiencing the same kinetics eluted with a mobile phase at fixed or varying composition. When the analysed solutes experience different resistance to mass transfer the plots will be solute dependent and should be obtained with the data for each solute eluted with mobile phases at varying composition. The half-width plots approach is a simple tool that facilitates the prediction of peak shape (width and asymmetry) with optimisation purposes reveal the interaction kinetics of solutes in different columns and characterise chromatographic columns. This work shows half-width plots for different situations in isocratic elution including the use of different flows the effect of temperature the modification of the stationary phase surface by an additive the existence of specific interactions within the column and the comparison of columns. The adaptation to gradient elution is also described. Previous knowledge on half-width plots is structured and analysed to which new results are added.Work (thermodynamics)Column characterisationmedia_common.quotation_subjectKineticsLiquid chromatographyAnalytical chemistryHalf-widthsInteraction kineticsBiochemistryAsymmetryAnalytical ChemistryPeak shapeColumn (typography)Position (vector)Mass transferPhase (matter)media_commonChromatographyElutionChemistryOrganic ChemistryGeneral MedicineModels TheoreticalKineticsPredictionChromatography LiquidJournal of Chromatography A
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