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Journal of Chromatography. A

Sander Jespers, Sander Deridder, Gert Desmet
A new type of microfluidic flow distributor (referred to as the mixed mode or MM-distributor) is proposed. Its performance characteristics are determined using computational fluid dynamics (CFD), both in the absence and the presence of clogging, which is an important problem in microfluidic systems. A comparison is made with two existing, well-performing distributor types: the bifurcating (BF) distributor and an optimized diverging distributor, the so-called radially interconnected (RI) distributor. It was found that, in the absence of clogging, the MM-distributor produces only a little more dispersion than the bifurcating (BF) distributor, but much less than the radially interconnected (RI) distributor...
January 12, 2018: Journal of Chromatography. A
Majors J Badgett, Barry Boyes, Ron Orlando
A model that predicts retention for peptides using a HALO® penta-HILIC column and gradient elution was created. Coefficients for each amino acid were derived using linear regression analysis and these coefficients can be summed to predict the retention of peptides. This model has a high correlation between experimental and predicted retention times (0.946), which is on par with previous RP and HILIC models. External validation of the model was performed using a set of H. pylori samples on the same LC-MS system used to create the model, and the deviation from actual to predicted times was low...
January 11, 2018: Journal of Chromatography. A
Xuemei Wang, Pengfei Huang, Xiaomin Ma, Xinzhen Du, Xiaoquan Lu
Novel magnetic mesoporous molecularly imprinted polymers (MMIPs) were prepared based on surface precipitation polymerization using Triclosan (TCS) as template and methacrylic acid as functional monomer. The synthesized MMIPs-TCS were applied to the adsorbent of magnetic solid-phase extraction (MSPE) coupled with HPLC for the enrichment and determination of TCS. The MMIPs-TCS were characterized by fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption transmission, and vibrating sample magnetometry...
January 10, 2018: Journal of Chromatography. A
Ibolya Prauda, Endre Bartó, Attila Felinger
The thermodynamics of the retention mechanism of resorcinarene-based cavitands in RPLC as well as the nature of the binding sites have been studied recently. In the present study, the influence of pressure on the retention of the cyclic tetramers on alkylsilyl and polar-embedded C8 and C18 stationary phases is investigated using aqueous methanol mobile phase. The pressure effect for cavity-shaped molecules has been scarcely studied so far. We observed that the retention factors of the analytes increased with the increase of the average column pressure (1-400 bar) when using restricting capillary tubes...
January 9, 2018: Journal of Chromatography. A
Mei Xu, Mengmeng Zheng, Guizhen Liu, Meng Zhang, Jingwu Kang
In the present study, a capillary electrophoresis (CE) method was developed for screening of inhibitors against the break point cluster region Abelson tyrosine kinase (BCR-ABL). The screening method was established by using 5-carboxyfluorescein labeled peptide substrate of BCR-ABL (F-ABLS), a known BCR-ABL tyrosine kinase inhibitor dasatinib, as well as a small chemical library consisting of 37 natural products. Thus, the inhibition of BCL-ABL kinase by small inhibitors was assayed by a CE system equipped with the laser induced fluorescence detector...
January 8, 2018: Journal of Chromatography. A
Yike Wu, Qiuyue Sha, Juan Du, Chang Wang, Liang Zhang, Bi-Feng Liu, Yawei Lin, Xin Liu
Robust, efficient identification and accurate quantification of N-glycans are of great significance in N-glycomics analysis. Here, a simple and rapid derivatization method, based on the combination of microwave-assisted deglycosylation and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) labeling, was developed for the analysis of N-glycan by high performance liquid chromatography with fluorescence detection (HPLC-FLD). After optimizing various parameters affecting deglycosylation and derivatization by RNase B, the time for N-glycan labeling was shortened to 50 min with ∼10-fold enhancement in detection sensitivity comparing to conventional 2-aminobenzoic acid (2-AA) labeling method...
January 8, 2018: Journal of Chromatography. A
Elise Lemasson, Sophie Bertin, Philippe Hennig, Eric Lesellier, Caroline West
The development of new active pharmaceutical ingredients (API) requires accurate impurity profiling. Nowadays, reversed-phase HPLC (RPLC) on C18 stationary phase is the method of first choice for this task and usually employed in generic screening methods. However, this method sometimes fails, especially when the target analyte is not sufficiently retained, making impurity analysis difficult or even impossible. In such cases, a second method must be available. In the present paper, we compare the merits of RPLC on C18 phase to those of previously optimized alternative methods, based on the analysis of a large and diverse set of small-molecule drug candidates...
January 8, 2018: Journal of Chromatography. A
Xue Ma, Xiaohua Zhou, Ajuan Yu, Wuduo Zhao, Wenfen Zhang, Shusheng Zhang, Linlin Wei, Debra J Cook, Anirban Roy
The facile preparation, characterization and application of a novel magnetic graphene oxide- metal organic framework [Zn2(d-Cam)2(4, 4'-bpy)]n (MGO-ZnCB) as a sorbent for fast, simple and enantioselective capture of chiral drug intermediates are presented in this paper. The MGO-ZnCB nanocomposite, developed by encapsulating MGO nanoparticles into the homochiral metal organic framework of ZnCB, can integrate the advantages from each component endowing the hybrids with improved synergystic effects. The enantioselective performance of MGO-ZnCB was evaluated by dispersive magnetic nanoparticle solid phase extraction (d-MNSPE) of 1, 1'-bi-2-naphthol (BN) and 2, 2'-furoin (Furoin) racemic solutions...
January 6, 2018: Journal of Chromatography. A
Wanwan Ma, Kyung Ho Row
A type of magnetic ionic liquid based molecularly imprinted polymer coated on SiO2 (Fe3O4@SiO2@IL-MIPs) was prepared with 1-vinyl-3-ethylimidazole ionic liquid as functional monomer, and 1,4-butane-3,3'-bis-1-ethylimidazole ionic liquid as cross linker, 4-Chlorophenol as template was successfully applied as a selective adsorbent for selective extraction of 5 chlorophenols in seawater samples by using the magnetic solid-phase extraction (MSPE) method. 11 types of Fe3O4@SiO2@IL-MIPs were synthesized and investigated for their different compositions of functional monomer (such as [C2min][Br], [C2min][BF4], [C2min][PF6], acrylamide, methacrylic acid and 4-vinyl pyridine) and cross-linker (such as [C4min2][Br], [C4min2][BF4], [C4min2][PF6], divinylbenzene, and ethylene glycol dimethacrylate), respectively...
January 6, 2018: Journal of Chromatography. A
Nina Duhamel, Davide Slaghenaufi, Lisa I Pilkington, Mandy Herbst-Johnstone, Roberto Larcher, David Barker, Bruno Fedrizzi
Sesquiterpenes are a widespread class of compounds of increasing interest found in grapes and wines, amongst many other natural sources. Due to a lack of standards and the complexity of the mass spectra fragmentation, accurate quantification of these low concentration compounds had not previously been accomplished. The current paper presents a new method for the concurrent quantification of several sesquiterpenes. The multivariate method optimisation is presented. Synthesised isotopic standards were utilised in conjunction with solid phase microextraction (SPME) and gas chromatography-tandem mass spectrometry (GC-MS/MS) to perform a standard isotope dilution assay (SIDA)...
January 5, 2018: Journal of Chromatography. A
Asma'a Al-Rifai, Ahmad Aqel, Lamya Al Wahibi, Zeid A ALOthman, Ahmed-Yacine Badjah-Hadj-Ahmed
A composite of multi-walled carbon nanotubes incorporated into a benzyl methacrylate-co-ethylene dimethacrylate porous monolith was prepared, characterized and used as solid phase adsorbent and as stationary phase for simultaneous extraction and separation of ten polycyclic aromatic hydrocarbons, followed by nano-liquid chromatography analysis. The extraction and chromatographic parameters were optimized with regard to the extraction efficiency and the quality of chromatographic analytes separation. Under the optimized conditions, all PAHs were separated in 13 min with suitable resolution values (Rs = 1...
January 4, 2018: Journal of Chromatography. A
Li-Jing Du, Ling Yi, Li-Hong Ye, Yu-Bo Chen, Jun Cao, Li-Qing Peng, Yu-Ting Shi, Qiu-Yan Wang, Yu-Han Hu
A simple and effective method of miniaturized solid-phase extraction (mini-SPE) was developed for the simultaneous purification and enrichment of macrolide antibiotics (MACs) (i.e. azithromycin, clarithromycin, erythromycin, lincomycin and roxithromycin) from honey and skim milk. Mesoporous MCM-41 silica was synthesized and used as sorbent in mini-SPE. Several key parameters affecting the performance of mini-SPE procedure were thoroughly investigated, including sorbent materials, amount of sorbent and elution solvents...
January 3, 2018: Journal of Chromatography. A
Marigianna Marinou, Dimitrios Platis, Farid S Ataya, Evangelia Chronopoulou, Dimitrios Vlachakis, Nikolaos E Labrou
In the present study, a structure-based approach was exploited for the in silico design of a nucleotide coenzyme mimetic ligand. The enzyme formate dehydrogenase (FDH) was employed as a model in our study. The biomimetic ligand was designed and synthesized based on a tryptamine/3-aminopropylphosphonic acid bi-substituted 1,3,5-triazine (Trz) scaffold (Tra-Trz-3APP), which potentially mimics the interactions of NAD+-FDH complex. Molecular docking studies of the biomimetic ligand predicted that it can occupy the same binding site as the natural coenzyme...
January 3, 2018: Journal of Chromatography. A
Shawn C Helmueller, Donald P Poe, Krzysztof Kaczmarski
An approach to conducting SFC separations under pseudo-adiabatic condition utilizing a dual-zone column heater is described. The heater allows for efficient separations at low pressures above the critical temperature by imposing a temperature profile along the column wall that closely matches that for isenthalpic expansion of the fluid inside the column. As a result, the efficiency loss associated with the formation of radial temperature gradients in this difficult region can be largely avoided in packed analytical scale columns...
January 3, 2018: Journal of Chromatography. A
Luisa A Ferreira, Vladimir N Uversky, Boris Y Zaslavsky
The phase diagram of a new aqueous two-phase system (ATPS) formed by polyethylene glycol with molecular weight 600 (PEG-600) and trimethylamine N-oxide (TMAO) in 0.01 M sodium phosphate buffer (NaPB), pH 7.4, is determined and hydrophobic, electrostatic and other solvent properties of the phases are characterized. The same properties are determined for the ATPS formed by PEG-600 and choline chloride in 0.01 M sodium phosphate buffer (NaPB), pH 7.4. Solvent properties of water (dipolarity/polarizability, hydrogen bond donor acidity, and hydrogen bond acceptor basicity) in aqueous solutions of polypropylene glycol-400 (PPG-400), polyethylene glycol dimethyl ether -250 (PEGDME-250), and choline chloride are determined at different concentrations...
January 3, 2018: Journal of Chromatography. A
Milen G Bogdanov, Ivan Svinyarov
Ionic liquid-based aqueous biphasic systems (IL-ABS) formed by ILs composed of ions of low toxicity, choline ([Chol]+) coupled with saccharinate ([Sac]-) and acesulfamate ([Ace]-), and inorganic salts with distinct water-structuring properties were employed for simultaneous extraction and concentration of acetylcholinesterase (AChE) inhibitors - galantamine (gal), N-desmethyl galantamine (des) and ungiminorine (ung). Comprehensive experiments aimed to assess the influence of salt and IL type and concentration, as well as the pH and temperature on the phase-forming ability and distribution of the target alkaloids between the two phases formed reveled that the IL anion and pH are the most important factors...
January 3, 2018: Journal of Chromatography. A
Peng Wang, Mai Luo, Donghui Liu, Jing Zhan, Xueke Liu, Fang Wang, Zhiqiang Zhou, Peng Wang
A novel magnetic nanocomposite was prepared and applied for the extraction of organophosphorus pesticide residue (malathion, chlorpyrifos, isocarbophos, fenamiphos, profenofos) in environmental water by magnetic solid phase extraction. The magnetic nanocomposite was synthesized by coating Fe3O4 with silicon dioxide and then bonding with graphene oxide under the catalytic action of hydrazine hydrate. A residue analysis method for the determination of organophosphorus pesticides in environmental water was established via magnetic solid phase extraction with the nanocomposite as the sorbent, followed by gas chromatography with flame photometric detection (GC-FPD)...
January 2, 2018: Journal of Chromatography. A
Tímea Orosz, Enikő Forró, Ferenc Fülöp, Wolfgang Lindner, István Ilisz, Antal Péter
In the present work the effects of N-methylation and N-amidination of ampholytic cyclic β-amino acids on their retention and enantioseparation characteristics on Cinchona alkaloid- and sulfonic acid-based zwitterionic chiral selectors, namely Chiralpak ZWIX(+)™ and ZWIX(-)™ columns are described. In a polar-ionic mobile phase, a double ion-pairing interaction mechanism takes place between the charged sites of the chiral analytes (the selectands) and the chiral selector moieties. As a support to correlate the chromatographic results with the structural details of the analytes, pKa values and van der Waals volumes of the substituted amino groups were calculated...
January 2, 2018: Journal of Chromatography. A
Shaogang Chu, Robert J Letcher
While reversed-phase (RP) liquid chromatography can separate a wide range of analytes, for strongly acidic compounds such as environmentally relevant dialkyl phosphates (DAPs), this remains a challenge because they have low affinity for standard RP columns or they exhibit inferior peak shapes. Mixed-mode chromatographic (MMC) columns, which contain both RP and ion-exchange functionalities, can address these resolution problems. However, using current MMC separation approaches, analyte peaks are relatively broad as compared to conventional RP chromatography...
January 2, 2018: Journal of Chromatography. A
Julia Rossmann, Lars David Renner, Reinhard Oertel, Ali El-Armouche
Liquid chromatography with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) technique is gaining more and more attraction as the method of choice for multi-sample analysis. However, it is strongly susceptible to the influence of matrix components. Matrix effects are the main source of substantial losses in detection sensitivity and have to be compensated via complex quantification methods In this work, we introduce a sophisticated quantification method for the LC-ESI-MS/MS analysis of 16 substances in urine samples using a single continuously post-column infused internal standard (PCI-IS) for matrix effect correction...
January 2, 2018: Journal of Chromatography. A
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