Gradient elution
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Helicteres family widely distributed from southern China to India, Southeast Asia. There are seven species in Vietnam and described as traditional medicinal plants. The information about the chemical constituents of Helicteres hirsuta in Vietnam has not been fully reported. In present work, we presented the isolation and structural elucidation of four terpenoids (1-4) isolated from Helicteres hirsuta L. which collected from Binh Phuoc province.
5p vidoctorstrange 06-05-2023 7 4 Download
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The aim of this study was the determination of chromatographic profiles of major whey proteins (WP): α-lactalbumin (α-La), β-lactoglobulin A and B, (β-Lg A and B), bovine serum albumin (BSA) in dairy beverages based on Zonar milk serum. The studied WP were separated by high-performance liquid chromatography (HPLC) on Aeris XB-C18 column using gradient elution with 0.1% trifluoroacetic acid (TFA) in water and 0.1% TFA in 80% acetonitrile, at 214 nm detection.
11p lyhuyenthu 31-01-2023 2 2 Download
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We investigated and compared the robustness of supercritical fluid chromatography (SFC) separations of the peptide gramicidin, using either isocratic or gradient elution. This was done using design of experiments in a design space of co-solvent fraction, water mass fraction in co-solvent, pressure, and temperature.
11p viginny 23-12-2022 7 3 Download
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The applicability of models to describe peptide retention in hydrophilic interaction liquid chromatography (HILIC) was investigated. A tryptic digest of bovine-serum-albumin (BSA) was used as a test sample. Several different models were considered, including adsorption, mixed-mode, exponential, quadratic and Neue–Kuss models.
8p viginny 23-12-2022 8 3 Download
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A combined experimental and theoretical study was performed to understand how the pore size of packing materials with pores 60–300 A˚ in size affects the separation of 5–50-mer oligonucleotides. For this purpose, we developed a model in which the solutes were described as thin rods to estimate the accessible surface area of the solute as a function of the pore size and solute size.
10p viginny 23-12-2022 6 3 Download
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This approach involves the use of multiple isocratic steps, together with the addition of a steep negative gradient segment (with a decrease in mobile phase strength) to "park" a slightly more retained peak somewhere along the column (at a given migration distance), while a slightly less retained compound can be eluted.
9p viginny 23-12-2022 4 3 Download
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Modern analytical applications of liquid chromatography require more and more efficient columns. In this work, the possibility of utilizing particle size gradient in the chromatographic column was studied by a theoretical approach. In the course of our work three different scenarios of particle size gradients were considered with different shapes (linear, convex and concave).
8p viginny 23-12-2022 12 3 Download
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Structural elucidation of compounds detected with liquid chromatography coupled to high resolution mass spectrometry is a challenging and time-consuming step in the workflow of non-targeted analysis and often requires manual validation of the results. Retention time, alongside exact mass, isotope pattern, fragmentation spectra, and collision cross-section, is valuable information for ruling out unlikely structures and increasing the confidence in others.
12p viginny 23-12-2022 6 2 Download
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The phenomenon of pH excursion was demonstrated for pH gradient elution of monoclonal antibodies (mAbs) on strong cation exchange resins under high overloading conditions. The mAbs differed in molecular structure and isoelectric point, and the resins in matrix structure and ligand density. In all cases, elution of the proteins was accompanied with distortion of the concentration, pH and conductometric profiles.
10p viginny 23-12-2022 10 3 Download
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We report here the improvement of a procedure to obtain global models, able to describe the retention behaviour of several sample components simultaneously. The reported global models include parameters that account for the general effects of column and solvent on retention and are common for all components, whereas other parameters are specific of each sample component.
13p viginny 23-12-2022 11 3 Download
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Various high-throughput systems and strategies are employed by the biopharmaceutical industry for early to late-stage process development for biologics manufacturing. The associated increases to experiment productivity and reduction in material consumption makes high throughput tools integral for bioprocess development.
11p vironald 15-12-2022 6 2 Download
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In this paper we demonstrate that the influence of the MWD can be reduced using very steep gradients and that such gradients are best realized utilizing recycling gradient liquid chromatography.
11p vironald 15-12-2022 7 3 Download
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Medicinal plants contain a large variety of chemical compounds in highly variable concentrations, so the quality control of these materials is especially complex. With this purpose, regulatory institutions have accepted chromatographic fingerprints as a valid tool to perform the analyses.
11p vironald 15-12-2022 9 2 Download
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The purpose of this work is to develop a tool to search for a gradient profile with ternary or binary mixtures in liquid chromatography, that can provide well-resolved chromatograms in the shortest time for multianalyte analysis.
13p vironald 15-12-2022 7 2 Download
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Separation of morphine and its impurities (related substances specified in relevant European Pharmacopoeia monographs, as well as the other naturally occurring coextracted alkaloids) was obtained within a close retention window on a reverse phase HPLC column, eluted with optimized gradient, consisting of methanol and 5 mM ammonium formate, adjusted to pH 10.2. Systematic optimization of the chromatographic conditions was carried out using design of experiments.
13p tudichquannguyet 29-11-2021 11 1 Download
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A simple, stable, and specific high-performance liquid chromatography coupled with a DAD detector (HPLC-DAD) method has been developed and validated for the simultaneous determination of amlodipine, felodipine, furosemide, nifedipine, and spironolactone in traditional herbal products. The analytes were extracted in acetonitrile: water (50 : 50, v/v) with help of the ultrasonic. The separation of analytes was performed in an Apollo C18 column (250 × 4.6 mm; 5 µm) and a mobile phase consisting of mixture acetonitrile: 0.1% phosphoric acid in gradient elution.
10p chauchaungayxua12 11-07-2021 12 1 Download
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A reversed phase high performance liquid chromatography (HPLC) method with UV detection by multi-step gradient elution method has been developed for simultaneous determination of testosterone, 17β-estradiol, 17α, 20β-dihydroxy-4- pregnen-3-one and cortisol in fish. The method described includes limited sample preparation with single step SPE using C18 cartridge.
8p quenchua4 16-04-2020 13 0 Download
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This study determined the optimal nutrient and environmental conditions to produce antimicrobial and cytotoxic agents by Streptomyces cavourensis YBQ59 during the fermentation process. The bioactivities of eluted fractions based gradient solvents via chromatography column were also evaluated. S.
9p chauchaungayxua2 07-01-2020 49 0 Download
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A new approach has been developed for the preparation of mixed-mode stationary phases to separate proteins. The pore surface of monolithic poly(glycidyl methacrylate-co-ethylene dimethacrylate) capillary columns was functionalized with thiols and coated with gold nanoparticles. The final mixed mode surface chemistry was formed by attaching, in a single step, alkanethiols, mercaptoalkanoic acids, and their mixtures on the free surface of attached gold nanoparticles. Use of these mixtures allowed fine tuning of the hydrophobic/hydrophilic balance.
8p trinhthamhodang1 16-11-2019 13 1 Download