Search results for "peak shape"

showing 3 items of 3 documents

Estimation of Solute-Stationary Phase and Solute-Mobile Phase Interactions in the Presence of Ionic Liquids

2019

The presence of free silanols on alkyl-bonded reversed-phase stationary phases is responsible for broad and asymmetrical peaks when basic drugs are chromatographed with conventional octadecylsilane (C18) columns due to ionic interactions. In the last few years, ionic liquids (ILs) have attracted attention to reduce this undesirable silanol activity. ILs should be considered as dual modifiers (with a cationic and anionic character), which means that both cations and anions are able to adsorb on the stationary phase, creating a positively or negatively charged layer, depending on the relative adsorption. The accessibility of basic compounds to the silanols is prevented by both the IL cation a…

Inorganic chemistryRPLCIonic bondingFiltration and Separation01 natural sciencesAnalytical ChemistryIonlcsh:Chemistryionic liquidschemistry.chemical_compoundAdsorptionPhase (matter)Triethylaminepeak shape010405 organic chemistry010401 analytical chemistryCationic polymerizationchemical equilibrialcsh:QC1-9990104 chemical sciencesSilanolbasic drugslcsh:QD1-999chemistryIonic liquidlcsh:PhysicsSeparations
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Anomalous Evolution of the Near-Side Jet Peak Shape in Pb-Pb Collisions at √sNN = 2.76 TeV

2017

The measurement of two-particle angular correlations is a powerful tool to study jet quenching in a pT region inaccessible by direct jet identification. In these measurements pseudorapidity (Δη) and azimuthal (Δφ) differences are used to extract the shape of the near-side peak formed by particles associated with a higher pT trigger particle (1<pT,trig<8  GeV/c). A combined fit of the near-side peak and long-range correlations is applied to the data allowing the extraction of the centrality evolution of the peak shape in Pb-Pb collisions at √sNN=2.76  TeV. A significant broadening of the peak in the Δη direction at low pT is found from peripheral to central collisions, which vanishes above 4…

Pb-Pb collisionsPhysics and Astronomy(all)hiukkasfysiikkaNuclear Experimentjet peak shape
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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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