Modelling oligomer formation in chromatographic separations

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011Jørgen M., MollerupOligomer forms of proteins are formed by self and cross association or complex formation with ligands. Modelling …

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011

Jørgen M., Mollerup

Oligomer forms of proteins are formed by self and cross association or complex formation with ligands. Modelling studies using an ion-exchange adsorbent have demonstrated that the formation of an oligomer form of a target protein can improve a chromatographic separation because the oligomer form displaces the impurities. The results of the investigation show that the process is very robust, that the purity, the yield, and the productivity increase with increasing load and increasing salt concentration in the eluant. An impurity level less than 1ppm is easy to achieve having a yield of 98%.A universal model for the adsorption equilibria of...

Method development and validation for optimised separation of salicylic, acetyl salicylic and ascorbic acid in pharmaceutical formulations by hydrophilic interaction chromatography and response surface methodology

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011Nader, Hatambeygi , Ghazaleh, Abedi , Mohammad, TalebiThis paper introduces a design of experiments (DOE) approach for method optim…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011

Nader, Hatambeygi , Ghazaleh, Abedi , Mohammad, Talebi

This paper introduces a design of experiments (DOE) approach for method optimisation in hydrophilic interaction chromatography (HILIC). An optimisation strategy for the separation of acetylsalicylic acid, its major impurity salicylic acid and ascorbic acid in pharmaceutical formulations by HILIC is presented, with the aid of response surface methodology (RSM) and Derringer's desirability function. A Box-Behnken experimental design was used to build the mathematical models and then to choose the significant parameters for the optimisation by simultaneously taking both resolution and retention time as the responses. The refined model had a satisfactory coefficient (R2>0.92, n=27). The four independent variables studied simultaneously...

DISPERSIVE DERIVATIZATION LIQUID-LIQUID EXTRACTION OF DEGRADATION PRODUCTS/PRECURSORS OF MUSTARDS AND V-AGENTS FROM AQUEOUS SAMPLES

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011Meehir, Palit , Gary, MallardA new derivatization and extraction technique termed as dispersive derivatization liquid–liquid extra…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011

Meehir, Palit , Gary, Mallard

A new derivatization and extraction technique termed as dispersive derivatization liquid–liquid extraction (DDLLE) speeds up the analysis process by removing the requirement for drying of the sample. The derivatization process takes place at the interface between the analyte containing aqueous phase and derivatization agent laden organic phase. The organic phase is highly dispersed using disperser solvent so that the total surface area is large. The derivatizing agent used is 1-(heptafluorobutyryl)imidazole and the resulting heptafluorobutyryl (HFB) derivatized analytes are partitioned into the organic phase. In addition to reduced sample preparation time, for some of the analytes, the HFB derivatives provide better...

Innovative HPLC method development for the screening of 19 antimalarial drugs based on a generic approach, using design of experiments, independent component analysis and design space

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011B., Debrus , P., Lebrun , J. Mbinze, Kindenge , F., Lecomte , A., Ceccato , …An innovative methodology based on design of exper…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011

B., Debrus , P., Lebrun , J. Mbinze, Kindenge , F., Lecomte , A., Ceccato , ...

An innovative methodology based on design of experiments (DoE),independent component analysis (ICA) and design space (DS) was developed in previous works and was tested out with a mixture of 19 antimalarial drugs. This global LC method development methodology (i.e. DoE-ICA-DS) was used to optimize the separation of 19 antimalarial drugs to obtain a screening method. DoE-ICA-DS methodology is fully compliant with the current trend of quality by design. DoE was used to define the set of experiments to model the retention times at the beginning, the apex and the end of each peak. Furthermore, ICA was used to numerically separate...

High-capacity composite adsorbents for nucleic acids

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011Peter, Tiainen , M. Rokebul, Anower , Per-Olof, LarssonCytopore ™ is a bead-shaped, macroporous and easily compressible cellulose…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011

Peter, Tiainen , M. Rokebul, Anower , Per-Olof, Larsson

Cytopore ™ is a bead-shaped, macroporous and easily compressible cellulose-based anion-exchange material intended for cultivation of anchor-dependent animal cells. Reticulated vitreous carbon (RVC) is a strong, non-compressible, high voidage (97%) matrix material that can be cut to desired geometrical shapes. Cytopore and RVC were combined to cylindrical composites (25×10mm) fitted inside chromatography columns. The composite combined the advantageous properties of both its constituents, making it suitable for column chromatography. The composite could withstand very high flow rates without compaction of the bed (>25 column volumes per minute; 4000cm h−1). Chromatography runs with tracers showed a low HETP value (0.3mm), suggesting...

DEVELOPMENT AND VALIDATION OF A CONFIRMATORY METHOD FOR THE DETERMINATION OF 12 NON STEROIDAL ANTI-INFLAMMATORY DRUGS IN MILK USING LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011Estelle, Dubreil-Chéneau , Yvette, Pirotais , Mélaine, Bessiral , Brigitte, Roudaut , Eric, VerdonA rapid and reliable LC-MS/MS…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011

Estelle, Dubreil-Chéneau , Yvette, Pirotais , Mélaine, Bessiral , Brigitte, Roudaut , Eric, Verdon

A rapid and reliable LC-MS/MS method for the simultaneous confirmation of twelve non steroïdal anti-inflammatory drugs (NSAIDs) in bovine milk was developed and fully validated in accordance with the European Commission Decision 2002/657/EC. The validation scheme was built in accordance with the MRLs or target analytical levels (EU-CRL recommended concentrations and detection capabilities) of the analytes, except for diclofenac for which the lower level of validation achieved was 0.5 μg kg−1 whereas its MRL is 0.1 μg kg−1. The NSAIDs investigated were as follows: phenylbutazone (PBZ), oxyphenylbutazone (OPB), naproxen (NP), mefenamic acid (MF), vedaprofen (VDP), flunixin (FLU), 5-hydroxyflunixin (FLU-OH), tolfenamic...

Practical Implications of the “Tanaka” Stationary Phase Characterization Methodology using Ultra High Performance Liquid Chromatographic Conditions

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011Melvin R., Euerby , Matthew, James , Patrik, PeterssonThe practical implications of performing column characterization protocols (i…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011

Melvin R., Euerby , Matthew, James , Patrik, Petersson

The practical implications of performing column characterization protocols (i.e. Tanaka) and their resultant chromatographic selectivity parameters using small dimension columns (i.e. 50×2.1mm I.D.) at high pressures have been critically compared to those obtained using conventional LC methodology. Retention factors should be corrected for the system extra column volume even when determined on Ultra High Performance Liquid Chromatographic (UHPLC) systems with low system volumes.An increase in pressure resulted in a general increase in the retention factor for most analytes, the degree being dependent on the physico/chemical properties of each analyte and the chromatographic conditions employed. However, analytes chromatographed at pH values...

Fast separations of chiral β-blockers on a cellulose tris(3,5-dimethylphenylcarbamate)-coated zirconia monolithic column by capillary electrochromatography

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011Avvaru Praveen, Kumar , Jung Hag, ParkCellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) isan excellent chiral selector for enantio…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011

Avvaru Praveen, Kumar , Jung Hag, Park

Cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) isan excellent chiral selector for enantioseparation of a wide variety of chiral compounds. The monolithic chiral columns are becoming popular in liquid chromatography and capillary electrochromatography. In this work, we present the fast separation of chiral β-blockers on a CDMPC-modified zirconia monolithic column by capillary electrochromatography (CEC). The porous zirconia monolithic capillary column was prepared by using the sol-gel technology and then zirconia surface modified with CDMPC. The enantioseparationswereperformed in reversed-phase (RP)eluents of a phosphate solution (pH 4.4)modifiedwith acetonitrile or alcohol. The enantioseparations of a set of eightchiral β-blockers were achieved in less than one minute. Influences...

Development of cadmium/silver/palladium separation by ion chromatography with quadrupole inductively coupled plasma mass spectrometry detection for off-line cadmium isotopic measurements

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011C., Gautier , M., Bourgeois , H., Isnard , A., Nonell , G., Stadelmann , …A separation method was investigated to perform off-l…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011

C., Gautier , M., Bourgeois , H., Isnard , A., Nonell , G., Stadelmann , ...

A separation method was investigated to perform off-line cadmium isotopic measurements on a 109Ag transmutation target. Ion chromatography (IC) with Q ICPMS detection (quadrupole inductively coupled plasma mass spectrometry detection) was chosen to separate cadmium from the isobarically interfering elements, silver and palladium, present in the sample. The optimization of chromatographic conditions was particularly studied. Several anion and cation columns (Dionex AG11®, CS10® and CS12®) were compared with different mobile phases (HNO3, HCl). The separation procedure was achieved with a carboxylate-functionalized cation exchange CS12 column using 0.5M HNO3 as eluent. The developed technique yielded satisfactory results in terms of separation...

Constructing Chiral Caves and Efficiently Separating Enantiomers of Glutamic Acid with Novel Surface-Imprinting Technique

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011Baojiao, Gao , Yingxin, Chen , Jiying, MenDimethylaminoethyl methacrylate (DMAEMA) was first graft-polymerized onto the surfaces of…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 12 June 2011

Baojiao, Gao , Yingxin, Chen , Jiying, Men

Dimethylaminoethyl methacrylate (DMAEMA) was first graft-polymerized onto the surfaces of micron-sized silica gel particles in the manner of “grafting from” in a solution polymerization system, obtaining the grafted particles PDMAEMA/SiO2. Then, the molecular imprinting towards the grafted PDMAEMA was conducted with one enantiomer of glutamic acid (Glu), L-Glu, as template molecule and with 2,2’-dichlorodiethylether (DCEE) as crosslinking agent by adopting the novel surface-molecular imprinting technique established by our research group, and the single enantiomer (L-Glu) molecule- imprinted material MIP-PDMAEMA/SiO2 was obtained. With another enantiomer of glutamic acid, D-Glu, as the contrast compound, the recognition property of MIP-PDMAEMA/SiO2 for L-Glu was...

Liquid phase microextraction applications in food analysis

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 7 June 2011María, Asensio-Ramos , Lidia M., Ravelo-Pérez , Miguel Ángel, González-Curbelo , Javier, Hernández-BorgesOver the last years, …

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 7 June 2011

María, Asensio-Ramos , Lidia M., Ravelo-Pérez , Miguel Ángel, González-Curbelo , Javier, Hernández-Borges

Over the last years, liquid-phase microextraction (LPME) in its different application modes (single drop microextraction, dispersive liquid-liquid microextraction and hollow fiber-LPME) has been increasingly applied for the extraction of both inorganic and organic analytes from different matrices. Its advantages over conventional extraction procedures (simplicity, effectiveness, rapidity and low consumption of organic solvents) has also attracted its application in the complex food analysis field, in which it has clearly provided good and challenging results. A comprehensive review dealing with those articles published since its introduction till the end of March 2011 is presented, offering also a critical vision of the analytical...

high-performance liquid chromatography COUPLED to direct analysis in real time mass spectrometry: INVESTIGATIONS ON GRADIENT ELUTION AND influence of complex matrices on signal intensities

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011Susanne, Beißmann , Wolfgang, Buchberger , Robert, Hertsens , Christian W., KlampflDirect analysis in real time (DART) time-of-fli…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011

Susanne, Beißmann , Wolfgang, Buchberger , Robert, Hertsens , Christian W., Klampfl

Direct analysis in real time (DART) time-of-flight mass spectrometry (TOF-MS) has been tested for its suitability as a detector for gradient elution HPLC. Thereby a strong dependency of signal intensity on the amount of organic solvent present in the eluent could be observed. Adding a make-up liquid (iso-propanol) post-column to the HPLC effluent greatly enhanced detection limits for early eluting compounds. Limits of detection achieved employing this approach were in the range of 7–27μgL−1 for the parabene test mixture and 15–87μgL−1 for the pharmaceuticals. In further investigations DART ionization was compared to several other widely used atmospheric pressure ionization methods...

Annealing of silica to reduce the concentration of isolated silanols and peak tailing in reverse phase liquid chromatography

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011Josh J., Newby , Michael A., Legg , Benjamin, Rogers , Mary J., WirthNon-porous, colloidal silica particles were annealed at three …

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011

Josh J., Newby , Michael A., Legg , Benjamin, Rogers , Mary J., Wirth

Non-porous, colloidal silica particles were annealed at three different temperatures, 800, 900 and 1050°C. The adsorption of lysozyme, a probe of surface roughness, was consistent with progressively reduced surface roughness as temperature increased. The heat treated silica particles were rehydroxylated and then used to pack UHPLC columns. The cationic protein lysozyme was used to probe silanol activity, which exhibited progressively less tailing as the annealing temperature increased. FTIR spectroscopy confirmed that the abundance of isolated silanols on the surface was reduced by annealing at 900°C or 1050°C. FTIR also revealed that there was markedly increased hydrogen bonding of the isolated...

The inuence of the memory e_ect on preparative sep arations using the amylose tris(3,5-dimethylphenylcarbamate) stationary phase

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011Joel, Putnam , Georges, GuiochonAcid/base mobile phase modi_ers a_ect enantioseparations in ways that are not yet under6 stood for th…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011

Joel, Putnam , Georges, Guiochon

Acid/base mobile phase modi_ers a_ect enantioseparations in ways that are not yet under6 stood for the lack of systematic studies, which makes the scale-up of preparative separations di_cult to predict. Shifts of the selectivity of certain pairs of enantiomers upon exposure of the column to these modi_ers is amply documented. Furthermore, once the modi_er has been removed from the mobile phase, the improved selectivity remains, this phenomenon has been named the memory e_ect. We selected four enantiomeric pairs for a systematic study of this memory e_ect. The selectivity of 4-chlorophenylalanine ethyl ester (4CPEE) improves after a solution of ethanesulfonic acid...

Speciation analysis of arsenic compounds in edible oil by ion chromatography – inductively coupled plasma mass spectrometry

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011Yun-Ling, Chu , Shiuh-Jen, JiangAn inductively coupled plasma mass spectrometer (ICP-MS) was used as an ion chromatographic (IC) dete…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011

Yun-Ling, Chu , Shiuh-Jen, Jiang

An inductively coupled plasma mass spectrometer (ICP-MS) was used as an ion chromatographic (IC) detector for the speciation analysis of arsenic in edible oil. The arsenic species studied include arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine and arsenocholine. Gradient elution using (NH4)2CO3 and methanol at pH 8.5 allowed the chromatographic separation of all species in less than 8minutes. Effluents from the IC column were delivered to the nebulizer of ICP-MS for the determination of arsenic. The concentrations of arsenic species have been determined in several used and fresh vegetable oil samples. In this study, a microwave-assisted extraction method was used...

Application of multiwall carbon nanotubes-based matrix solid phase dispersion extraction for determination of hormones in butter by gas chromatography mass spectrometry

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011Rui, Su , Xinghua, Wang , Xu, Xu , Ziming, Wang , Dan, Li , …The multiwall carbon nanotubes (MWCNTs)-based matrix solid phase di…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011

Rui, Su , Xinghua, Wang , Xu, Xu , Ziming, Wang , Dan, Li , ...

The multiwall carbon nanotubes (MWCNTs)-based matrix solid phase dispersion (MSPD) was applied for the extraction of hormones, including 17-α-ethinylestradiol, 17-α-estradiol, estriol, 17-β-estradiol, estrone, medroxyprogesterone, progesterone and norethisterone acetate in butter samples. The method includes MSPD extraction of the target analytes from butter samples, derivatization of hormones with heptafluorobutyric acid anhydride-acetonitrile mixture, and determination by gas chromatography-mass spectrometry. The mixture containing 0.30g graphitized MWCNTs and 0.10g MWCNTs was selected as absorbent. Ethyl acetate was used as elution solvent. The elution solvent volume and flow rate were 12mL and 0.9mLmin−1 respectively. The recoveries of hormones obtained by analyzing the five spiked butter...

On-line concentration sample stacking coupled with water-in-oil microemulsion electrokinetic chromatography

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011Hsi-Ya, Huang , Wan-Ling, Liu , Brenda, Singco , Shih-Huan, Hsieh , Yung-Han, ShihThis study describes for the first time, the abi…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011

Hsi-Ya, Huang , Wan-Ling, Liu , Brenda, Singco , Shih-Huan, Hsieh , Yung-Han, Shih

This study describes for the first time, the ability of a normal stacking mode (NSM) on-line concentration step coupled with water-in-oil (W/O) microemulsion electrokinetic chromatography (MEEKC), using six common penicillin antibiotics (oxacillin, penicillin V, penicillin G, nafcillin, ampicillin, and amoxicillin) as test analytes. Optimization of penicillin separation in the conventional W/O MEEKC system demonstrated that change in the type and concentration of the oil phase (1-butanol) and column temperature had a pronounced effect on the separation. With the subsequent development of the NSM coupled with W/O MEEKC, improved separation and detection sensitivities were observed when an organic solvent plug (1-propanol;...

Morphological analysis of physically reconstructed capillary hybrid silica monoliths and correlation with separation efficiency

Publication year: 2011Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011Stefan, Bruns , Takeshi, Hara , Bernd M., Smarsly , Ulrich, TallarekWe report an experimental study on the structural (especially r…

Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 1 June 2011

Stefan, Bruns , Takeshi, Hara , Bernd M., Smarsly , Ulrich, Tallarek

We report an experimental study on the structural (especially radial) heterogeneity of eleven 100μm i.d. capillary tetramethoxysilane-methyltrimethoxysilane hybrid silica monoliths with different pore and skeleton sizes, which were imaged by an optimized confocal laser scanning microscopy method. This method allows the optical sectioning of the monoliths, which is a prerequisite for quantitative morphological image analysis. Both radial porosity profiles and chord length distributions were calculated in the macropore domain for each column from at least 100 complete cross-sectional views along the column axis. The statistical approach visualized radial heterogeneities on different length scales in the monolithic structures. Chord length distributions...