Linear Chromatography

Guiochon, Georges; Shirazi, Dean G.; Felinger, Attila; Katti, Anita M.

doi:10.1016/b978-012370537-2/50030-8

Cited by 305 publications

(727 citation statements)

References 110 publications

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“…Although the injection of sample causes this perturbation, the sample and this perturbation do not elute at the same time from the column. This phenomenon is predicted under nonlinear elution conditions by chromatographic theory and has been observed in recent experiments (7)(8)(9)(10). Molecules contained in the injected pulse exit as a "mass" peak which cannot be observed directly unless these molecules are distinguishable from the competing agent by an appropriate detector (e.g., using an isotopically-labeled analyte and a radioactivity detector or mass spectrometer; see chromatograms in Ref.…”

mentioning

confidence: 65%

“…Both zonal elution and frontal analysis have been shown to give comparable binding parameters when their data are fit to the appropriate equations [13]. However, frontal analysis gives raw adsorption isotherm data while zonal elution gives the best estimates of the isotherm parameters [9]. As a result, frontal analysis is not subject to errors due to differences in mass peaks versus perturbation peaks.…”

Section: Nih-pa Author Manuscriptmentioning

confidence: 99%

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Immobilization of α1-acid glycoprotein for chromatographic studies of drug–protein binding II. correction for errors in association constant measurements

Mallik

Xuan

Guiochon

et al. 2008

Analytical Biochemistry

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A new method for the immobilization of α 1 -acid glycoprotein (AGP) in HPLC columns was recently described for applications such as drug binding studies. Part of this earlier work used self-competition zonal elution studies to measure association equilibrium constants between immobilized AGP and R-or S-propranolol. It was later found that analysis of these data by a common equation derived for linear elution conditions gave erroneous values for experiments actually conducted under nonlinear conditions. This report discusses the nature of this error and uses frontal analysis to estimate the true binding strength between R-and S-propranolol and HPLC columns containing immobilized AGP.A recent paper examined the binding of R-and S-propranolol to a new type of α 1 -acid glycoprotein (AGP) column (1). Part of this earlier work used self-competition zonal elution studies for association equilibrium constant measurements, an approach which has since been noted to contain some errors that are not uncommon in the literature but that do need to be corrected to better estimate the true binding strength of R-and S-propranolol with AGP.The column used in Ref.(1) was prepared through the controlled and mild oxidation of AGP, followed by the immobilization of this protein to hydrazide-activated silica. Part of this paper evaluated binding of this AGP column to R-and S-propranolol by using a self-competition zonal elution experiment (i.e., the "perturbation method", "step and pulse method" or "system peak" method) (2-4). In this approach, a small sample of R-or S-propranolol was injected as a pulse onto the AGP column while a known, fixed concentration of the same compound was applied in the mobile phase as a competing agent. The resulting shift in the retention factor (k') for the observed peak was measured as a function of the mobile phase concentration of the analyte [A]. Plots of 1/k' versus [A] appeared to give a linear response for mobile phases containing 0 to 5 µM propranolol.In these experiments (1), association equilibrium constants were obtained by fitting the data to an equation from the literature that pertains to an analyte at infinite dilution, or "linear elution conditions" (see Eq. 1 in Ref. 1 and equivalent equations in Refs. 5 and 6). However, for an analyte at a finite concentration, this same equation can introduce errors when obtaining *Author for correspondence: Phone 402-472-2744; FAX 402-472-9402; Email, dhage@unlserve.unl.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author...

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confidence: 65%

Section: Nih-pa Author Manuscriptmentioning

confidence: 99%

Immobilization of α1-acid glycoprotein for chromatographic studies of drug–protein binding II. correction for errors in association constant measurements

Mallik

Xuan

Guiochon

et al. 2008

Analytical Biochemistry

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“…This method should only be employed if the isotherms are very precisely measured in a rather wide concentration range [24]. Furthermore, the fitted parameters of the commonly used isotherm equations do not provide directly useful information for technical applications or even only for judging the selectivity of adsorption.…”

Section: The Need For Isotherm Measurements In Mip Characterizationmentioning

confidence: 99%

Isotherm charts for material selection and method development with molecularly imprinted polymers and other sorbents

Dorkó

Tamás

Horvai

2017

Talanta

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A simple and efficient method is presented for assessing molecularly imprinted polymers (MIP) and other sorbents from the point of view of practical applications. The adsorption isotherms of the compounds, which need to be separated or detected in an application, are constructed from a small number of measured points on a log-log chart and then are compared graphically. Despite its simplicity and robustness this method reveals the information needed for optimal selection between MIPs and alternative sorbents. The design of separation or detection methods with MIPs is also supported by the proposed graphical isotherm comparison. Many experimental isotherms are presented supporting the proposed method.

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“…The binding properties of the materials were determined by classical staircase frontal analysis (for a proper understanding of the technique, reading of references [17,18] is suggested). For this purpose, stock solutions of S-NAP or IBU were prepared in 0.05% acetic acid in MeOH at two different concentrations: 0.05 and 0.5 mmol/L.…”

Section: Chromatographic Evaluationmentioning

confidence: 99%

Imidazolium-based functional monomers for the imprinting of the anti-inflammatory drug naproxen: Comparison of acrylic and sol–gel approaches

Kadhirvel

Azenha

Shinde

et al. 2013

Journal of Chromatography A

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a b s t r a c tImidazolium-based monomers were, for the first time, employed in a comprehensive investigation of the molecular imprinting process of naproxen in both acrylic and sol-gel tridimensional networks. To this end, molecularly imprinted polymer (MIP) and xerogel (MIX) were both optimized for performance, by testing different porogen, template speciation and component ratios. The developed imprints were characterized for their pore properties (nitrogen adsorption analysis), site heterogeneity, binding properties and other performance parameters such as the imprinting factor, selectivity (HPLC column tests), column efficiency and mass transfer kinetics (frontal analysis study). MIP exhibited mesoporosity (D p 29 nm), whereas MIX did not, which was reflected in both the lower number of accessible imprinted sites (4.9 mol/g versus 3.7 mol/g) and the slower binding/dissociation in MIX. The naproxen/ibuprofen selectivity ratio was estimated as 6.2 for the MIX and 2.5 for the MIP. Given the high importance of capacity and fast mass transfer in typical applications of imprinted materials, and the satisfactory selectivity of MIP, it can be concluded that the acrylic approach was globally the most advantageous. Still, the remarkably high selectivity of MIX and its reasonable capacity demonstrate that future work devoted to further optimization of both formats is worthwhile.

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Linear Chromatography

Cited by 305 publications

References 110 publications

Immobilization of α1-acid glycoprotein for chromatographic studies of drug–protein binding II. correction for errors in association constant measurements

Immobilization of α1-acid glycoprotein for chromatographic studies of drug–protein binding II. correction for errors in association constant measurements

Isotherm charts for material selection and method development with molecularly imprinted polymers and other sorbents

Imidazolium-based functional monomers for the imprinting of the anti-inflammatory drug naproxen: Comparison of acrylic and sol–gel approaches

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