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Wojciech Kazimierz Marek, Wojciech Piątkowski, Dorota Antos
The retention behavior of polyethylene glycol (PEG) on different types of hydrophobic interaction chromatography (HIC) resins containing butyl, octyl, and phenyl ligands was analyzed. An incomplete elution or splitting of the polymer peak into two parts was observed, where the first one was eluted at the dead time of the column, whereas the second one was strongly retained. The phenomenon was attributed to conformation changes of the polymer upon its adsorption on hydrophobic surface. The effect enhanced with increasing molecular weight of the polymer and hydrophobicity of the HIC media...
2018: Chromatographia
Tomasz Krawczyk, Mariusz Zalewski, Anna Janeta, Paweł Hodurek
Meso- and macroporous spherical silica gels of pore sizes in the range of 60-1000 Å and 40-75 µm particle size were investigated as a stationary phase for the separation and purification of polysaccharides and poly(ethylene glycols) (PEGs) of various MWs using an aqueous mobile phase. Sephadex and Bio-Gel were used for comparison as the most common stationary phases for similar purposes. The separation of dextrans of a mean MW = 31 kDa from small molecules (NaCl) was possible with SiO2 with a pore size of 60-300 Å, but the observed efficiencies of a column of the same size were lower comparing with Sephadex or Bio-Gel...
2018: Chromatographia
Tomasz Kowalkowski, Mateusz Sugajski, Bogusław Buszewski
Asymmetrical flow field-flow fractionation (AF4) and hollow-fiber flow field-flow fractionation (HF5) are techniques widely used in analytical, industrial and biological analyses. The main problem in all AF4 and HF5 analyses is sample loss due to analyte-membrane interactions. In this work the impact of liquid carrier composition on latex nanoparticles (NPs) separation in water and two different concentrations of NH4 NO3 was studied. In AF4, a constant trend of decreasing the size of 60 and 121.9 nm particles induced by the ionic strength of the carrier liquid has been observed...
2018: Chromatographia
Anna Gumieniczek, Justyna Galeza, Tomasz Mroczek, Krzysztof Wojtanowski, Katarzyna Lipska, Rafał Pietras
Dihydralazine and hydrochlorothiazide were stored at high temperature and humidity, under UV/Vis light and different pH, as individual drugs and the mixture. Then, a sensitive and selective HPLC-UV method was developed for simultaneous determination of dihydralazine and hydrochlorothiazide in presence of their degradation products. Finally, the degradation products were characterized through LC-DAD and LC-MS methods. Dihydralazine was sensitive to high temperature and humidity, UV/Vis light and pH ≥ 7...
2018: Chromatographia
Mariusz G Fleszar, Jerzy Wiśniewski, Małgorzata Krzystek-Korpacka, Błażej Misiak, Dorota Frydecka, Joanna Piechowicz, Katarzyna Lorenc-Kukuła, Andrzej Gamian
Nitric oxide (NO) is a small molecule involved in the regulation of many physiological processes. It plays a crucial role in the regulation of nervous system, immune and inflammatory responses, and blood flow. NO is synthesized by nitric oxide synthase (NOS) during two-step oxidation of l-arginine to l-citrulline. Intermediates and derivatives of NO metabolism, such as l-arginine, l-citrulline, asymmetrical dimethylarginine (ADMA), symmetrical dimethylarginine (SDMA), and dimethylamine (DMA), are investigated as potential biomarkers...
2018: Chromatographia
Anna Czajkowska-Mysłek, Joanna Leszczyńska
Baby food has never been the object of biogenic amine profiling. The aim of this study was to develop a highly sensitive method for analysis of biogenic amines in ready-to-eat baby foods. The principle of the developed method involves high-performance liquid chromatography coupled to single-quadrupole mass spectrometry (HPLC-APCI-MS) of dansyl derivatives, presented also in comparison with common diode array and fluorescence detection systems. The confirmation of correct identification of derivatives was performed by in-source fragmentation of the product ion at 170  m / z , performed only in one MS analyzer...
2018: Chromatographia
Jörgen Samuelsson, Marek Leśko, Martin Enmark, Joakim Högblom, Anders Karlsson, Krzysztof Kaczmarski
The overreaching purpose of this study is to evaluate new approaches for determining the optimal operational and column conditions in chromatography laboratories, i.e., how best to select a packing material of proper particle size and how to determine the proper length of the column bed after selecting particle size. As model compounds, we chose two chiral drugs for preparative separation: omeprazole and etiracetam. In each case, two maximum allowed pressure drops were assumed: 80 and 200 bar. The processes were numerically optimized (mechanistic modeling) with a general rate model using a global optimization method...
2018: Chromatographia
Victoria Raks, Hossam Al-Suod, Bogusław Buszewski
Development of efficient methods for isolation and separation of biologically active compounds remains an important challenge for researchers. Designing systems such as organomineral composite materials that allow extraction of a wide range of biologically active compounds, acting as broad-utility solid-phase extraction agents, remains an important and necessary task. Selective sorbents can be easily used for highly selective and reliable extraction of specific components present in complex matrices. Herein, state-of-the-art approaches for selective isolation, preconcentration, and separation of biologically active compounds from a range of matrices are discussed...
2018: Chromatographia
Katarzyna Macur, Jolanta Grzenkowicz-Wydra, Lucyna Konieczna, Jacek Bigda, Caterina Temporini, Sara Tengattini, Tomasz Bączek
The exposure of HeLa cells to interleukin-1 alpha (IL-1α) in the presence of cycloheximide (CHX) leads to the release of active tumor necrosis factor alpha (TNF-α), eliciting cytocidal effect on these cells. A mass spectrometry (MS)-based analysis of the qualitative proteomic profiles of the HeLa cells treated only with IL-1α, CHX or simultaneously with IL-1α and CHX, in comparison to an untreated control, enabled to distinguish protein candidates possibly involved in this process. Among them protein disulphide isomerase (PDI) seemed to be particularly interesting for further research...
2018: Chromatographia
Olivier Mozziconacci, Jordan T Stobaugh, Rupesh Bommana, Joshua Woods, Edward Franklin, James W Jorgenson, M Laird Forrest, Christian Schöneich, John F Stobaugh
In recent years protein therapeutics have seen increasing use in the therapeutic arena. As with traditional small molecule drug substances, one is obligated to ensure purity and stability of the various dosage forms. With these higher molecular weight therapeutics a common approach for analytical characterization is enzymatic digestion followed by gradient elution liquid chromatography with mass spectrometry detection to create a peptide map (bottom-up protein analysis). Due to the difficult to separate mixtures frequently encountered, there is the need for advanced chromatographic systems featuring increased resolution and/or peak capacity that can be operated in the gradient elution format...
September 2017: Chromatographia
André M Striegel
The specific refractive index increment (∂ n /∂ c ) is an essential datum for the accurate quantitation of molar mass averages and distributions ( inter alia ) of macromolecules when refractometry, static light scattering, and/or viscometry detection are coupled on-line to size-based separation techniques. The latter include methods such as size-exclusion and hydrodynamic chromatography, and asymmetric and hollow-fiber flow field-flow fractionation. The ∂ n /∂ c is also needed for accurate determination of the weight-average molar mass of polymers by off-line, batch-mode multi-angle static light scattering...
June 2017: Chromatographia
Katarzyna Adamska, Beata Strzemiecka, Rafał Brożek, Ryszard Koczorowski, Adam Voelkel
The use of elastic materials favours degradation of their surface. The period of their clinical usefulness is then shortened, and their further utilisation in the oral cavity may have the reverse effect. The surface properties of such material as well as the influence of the humidity on their surface are very important as they determine the prosthetic materials behavior in the mouth. The surface of such material should be resistant to water. Inverse gas chromatography is an accurate, sensitive technique for studying surface properties...
2017: Chromatographia
Bryce J Marquis, Hayley P Louks, Chhanda Bose, Robert R Wolfe, Sharda P Singh
Small molecules containing carboxylic acid functional groups are ubiquitous throughout biology, playing vital roles in biological chemistry ranging from energy metabolism to cellular signaling. This paper describes a new derivatization reagent, 4-bromo- N -methylbenzylamine, which was selected for its potential to derivatize mono-, di- and tri-carboxylic acids, such as the intermediates of the tricarboxylic acid (TCA) cycle. This derivatization procedure facilitated the use of positive electrospray ionization (ESI) tandem mass spectrometry (MS/MS) detection of derivatized species allowing for clear identification thanks to the easily recognizable isotope pattern of the incorporated bromine...
2017: Chromatographia
Joanna Legat, Magdalena Matczuk, Andrei Timerbaev, Maciej Jarosz
A full understanding and mediation of nanoparticle-serum protein interactions is key to design nanoparticles with vivid functions within the body, and to solve this problem one needs to differentiate and characterize individual nano-protein conjugates. In this paper, the authors applied capillary electrophoresis combined with inductively coupled plasma mass spectrometry detection to study the behavior of gold nanoparticles of different geometry, size and surface functionalization upon interacting with serum proteins and their mixtures...
2017: Chromatographia
Grażyna Wejnerowska
A single-drop microextraction (SDME) was developed for the analysis of volatile fatty acids (VFAs) (C2-C7) in water by gas chromatography (GC) with flame ionization detection. The significant parameters affecting the SDME performance such as selection of microextraction solvent, extraction time, stirring rate, sample pH and temperature, and ionic strength were studied and optimized. To lower limits of detection, derivatization of VFAs by N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) was performed...
2017: Chromatographia
Dennis Åsberg, Marek Leśko, Tomas Leek, Jörgen Samuelsson, Krzysztof Kaczmarski, Torgny Fornstedt
ABSTRACT: In electrostatic repulsive interaction chromatography, using a charged surface hybrid sorbent carrying positive charges can improve the peak shape of peptides in reversed-phase liquid chromatography (RP-LC), especially in overloaded conditions, compared with standard C18 sorbents. However, the positive surface charges can interact with anionic additives commonly used in peptide separations, e.g., trifluoroacetic acid (TFA), complicating adsorption isotherm estimation. We investigated how the competition for available adsorption sites between TFA and two peptides influenced the adsorption isotherm in gradient elution...
2017: Chromatographia
Irena Malinowska, Marek Studziński, Henryk Malinowski, Maria Gadzikowska
Thin layer techniques proved their usefulness in the analysis of plant extract material. Thanks to their low operation costs, high sample throughput and possibility to gather chromatographic data for the whole sample in a single act, they allowed to find, and in some cases identify, active ingredients often hidden in sophisticated plant extract matrices. It was also proved that the presence of a magnetic field changes the retention of some substances, and moreover changes the separation efficiency of chromatographic systems...
2017: Chromatographia
A Astefanei, I Dapic, M Camenzuli
The central dogma of biology proposed that one gene encodes for one protein. We now know that this does not reflect reality. The human body has approximately 20,000 protein-encoding genes; each of these genes can encode more than one protein. Proteins expressed from a single gene can vary in terms of their post-translational modifications, which often regulate their function within the body. Understanding the proteins within our bodies is a key step in understanding the cause, and perhaps the solution, to disease...
2017: Chromatographia
Andrzej Czyrski
ABSTRACT: Fluoroquinolones of the third and fourth generation posses wide bactericidal activity. Monitoring concentrations of antibacterial agents provides effective therapy and prevents the increase of bacterial resistance to antibiotics. The pharmacodynamic parameters that best describe fluoroquinalone activity are AUC/MIC and Cmax/MIC. Determining the level of this type of drug is essential to reach the effective concentration that inhibits the growth of bacteria. Determining the pharmaceutical formulation confirms the purity of a substance...
2017: Chromatographia
André M Striegel
No abstract text is available yet for this article.
August 2016: Chromatographia
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