Analytical Method and Assay
Emmanuel Lesaffre, Gianluca Baio, Bruno Boulanger in Bayesian Methods in Pharmaceutical Research, 2020
The high-performance liquid chromatography (HPLC) method is a technique used to separate compounds of interest (e.g. API and impurities). Compounds are transported using a liquid solvent (the mobile phase), by creating affinities between them and a solid phase. This latter is generally a column containing solid adsorbent particles (e.g. silica or polymers) with various nature, allowing the fine tuning of affinities between the mobile and solid phases. During the time the compounds and the mobile phase are percolating through the solid phase, the formers are being physically separated, allowing further analysis, such as detection, quantitation, or extraction of purified material in the case of preparative chromatography. Visualization of this separation process is made through a chromatogram, generally consisting of a graph of the absorption of UV/visible light vs. the time peaks/compounds go out of the solid phase (time referred as elution time). Each peak thus shows the presence of some compounds absorbing some light wavelength (see Figure 20.5). When peaks are well separated, the chromatogram shows that compounds are physically well separated.
Conjugation and Other Methods in Polymeric Vaccines
Mesut Karahan in Synthetic Peptide Vaccine Models, 2021
Chromatography is known as an important biophysical technique that can separate, identify, and purify the blend segments for subjective and quantitative investigation. Proteins can be purified based on properties such as size and shape, total charge, hydrophobic groups present on the surface, and the ability to bind to the stationary phase. It is based on molecular properties and interaction type use mechanism, four separation technologies, ion exchange, dispersion, surface adsorption, and size exclusion. Column chromatography is one of the most used and common techniques for protein purification methods. This technique is basically used to purify biological molecules. The application of the method can be summarized as follows. The sample is separated on the column (stationary phase) and then the wash buffer is added to the column (mobile phase). It flows through the column material placed on the fiberglass support. With the help of the wash buffer, the samples are accumulated at the bottom of the column chromatography instrument, based on time and volume (Coskun 2016). Column chromatography is a powerful purification and separation process that is closely controlled to the hydrodynamic diameters of the macromolecules depending on the diameter of the pores in the filling material (see in HPLC Method) (Acar 2006; Fornaguera and Solans 2018).
Basics Of Gas Chromatography Mass Spectrometry System
Raquel Cumeras, Xavier Correig in Volatile organic compound analysis in biomedical diagnosis applications, 2018
Within GC systems all the relevant parameters such as flow rate and subsequent heat zones (such as injector port, initial and final GC temperature, ramp rate and MS transferline interface) can be precisely controlled and adjusted as required. The GC system typically uses ultra high purity Helium (H2) as a carrier gas, which also serves to remove oxygen and other reactive gases from the system. Constant linear flow velocity within the GC column is maintained at all times and across the entire temperature range of the analysis with the use of variable digital mass flow controllers since gas viscosity decreases with increasing temperature. The constant linear flow rate is essential in generating a reproducible chromatographic profile for chemical separation.
Mortality among Tennessee Eastman Corporation (TEC) uranium processing workers, 1943–2019
Published in International Journal of Radiation Biology, 2023
John D. Boice, Sarah S. Cohen, Michael T. Mumma, Ashley P. Golden, Sara C. Howard, David J. Girardi, Elizabeth D. Ellis, Michael B. Bellamy, Lawrence T. Dauer, Keith F. Eckerman, Richard W. Leggett
TEC operated the electromagnetic separation process from 1943 to 1947 and employed the largest number of workers of all the early uranium processing plants involved in the Manhattan Project. The plant converted uranium oxide (UO3) received from the Mallinckrodt Chemical Works in Missouri to uranium chloride (UCl4). The UCl4 was then enriched, i.e. the percentage of 235U was increased by the calutron (mass spectrometer) electromagnetic separation process. The separation process involved two stages (‘alpha’ and ‘beta’), each consisting of multiple calutron separators. The alpha stage was discontinued in late 1945, when enriched uranium fluoride (UF6) was received from the Oak Ridge gaseous diffusion plant (K-25), converted to UF4, enriched further by the beta calutrons, and shipped to LANL for development of nuclear weapons.
Controlling the internal morphology of aqueous core-PLGA shell microcapsules: promoting the internal phase separation via alcohol addition
Published in Pharmaceutical Development and Technology, 2019
Samer R. Abulateefeh, Ghada K. Al-Adhami, Mahmoud Y. Alkawareek, Alaaldin M. Alkilany
In this study, we investigated the effect of incorporating different types of alcohols on the internal core architecture of PLGA microcapsules prepared by the internal phase separation method. While alcohol-free formulation ended up with only around 51% of mononuclear microcapsules, incorporating alcohols into the internal phase resulted in the formation of more than 90% of mononuclear microcapsules. Among the evaluated alcohols, octanol, in particular, exhibited an outstanding performance as its incorporation led to an immediate formation of almost entirely mononuclear microcapsules. Our study unveiled an interesting promoting effect of alcohol incorporation on the production of mononuclear microcapsules. This can be explained by their effect on altering one or more of the physiochemical properties of the internal phase, such as solvent partitioning and interfacial tension, which would ultimately affect various events in the phase separation process including water nucleation, shape relaxation, phase inversion, and migration of the coacervates. The ability to finely tune the internal core architecture of PLGA microcapsules is expected to have an important impact on various applications in a wide range of industries including, but not limited to, pharmaceutical, agricultural, textile, and food industries.
Pharmacokinetics and bioequivalence of a generic empagliflozin tablet versus a brand-named product and the food effects in healthy Chinese subjects
Published in Drug Development and Industrial Pharmacy, 2020
Xin Li, Lihua Liu, Yang Deng, Yuan Li, Ping Zhang, Yangyang Wang, Bing Xu
The plasma concentrations of empagliflozin was analyzed by Shimadzu HPLC system (Kyoto, Japan) coupled with an Applied Biosystems SCIEX 4000 Q TRAP mass spectrometer (AB SCIEX 4000 Q TRAP, Toronto, Canada). The liquid chromatographic separation process was conducted on an ACQUITY UPLC BEH C18 column (2.1 × 50 mm, 1.7 µm), supplied by Waters (Shanghai, China). The mobile phase composition was water containing 0.025% ammonia (solvent A) and acetonitrile (solvent B). The flow rate was 0.600 mL/min, with a gradient elution as follows: 0.01–1.40 min, slow linear increase of B from 30% to 40%; 1.40–1.41 min, rapid linear increase of B from 40% to 90%; 1.41–2.20 min, isocratic A:B = 10:90; 2.21–2.80 min, switching back to 30% B and holding for equilibrium. The auto-sampler and column temperature were set at 8 °C and 40 °C, respectively.
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