Iskanje po katalogu digitalne knjižnice

Opis: Achiral building blocks forming achiral structures is a common occurrence in nature, while chirality emerging spontaneously from an achiral system is usually associated with important scientific phenomena. We report on the spontaneous chiral symmetry-breaking phenomena upon the topographic confinement of achiral lyotropic chromonic liquid crystals in periodically arranged micrometer scale air pillars. The anisotropic fluid arranges into chiral domains that depend on the arrangement and spacing of the pillars. We characterize the resulting domains by polarized optical microscopy, support their reconstruction by numerical calculations, and extend the findings with experiments, which include chiral dopants. Well-controlled and addressed chiral structures will be useful in potential applications like programmable scaffolds for living liquid crystals and as sensors for detecting chirality at the molecular level.
Ključne besede: physical chemistry, atmospheric chemistry, chromatography, deformation, silicon, symmetry breaking, chiral domains, liquid crystal
Objavljeno v DKUM: 03.04.2025; Ogledov: 0; Prenosov: 1
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Ključne besede: e-liquids, chromatography, mass spectrometry
Objavljeno v DKUM: 29.01.2025; Ogledov: 0; Prenosov: 3
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Opis: The food supplement market is growing as many consumers wish to complement their nutrient intake. Despite all the regulations in place to ensure food supplements safety, there are still many cases of irregularities reported especially connected to internet sales. Twenty resveratrol food supplement products sold on the Slovenian market were evaluated on their compliance of declared vs. determined resveratrol content, as well as the compliance of labels with the European Union (EU) and Slovenian regulatory requirements. Both the ingredient contents and food information are important parts of food safety. Analyses of 20 food supplements performed using high-performance thin-layer chromatography (HPTLC) coupled with densitometry showed that 95% of products had contents different from what was declared and 55% of products contained higher contents than declared. In 25% of the products the determined content per unit exceeded the maximum level (150 mg/day) specified in EU novel food conditions for food supplement with trans-resveratrol. Evaluation of the 20 food supplement labels included mandatory and voluntary food information, food supplement information, novel food information, health claims and nutrition claims. Most labels contained the necessary information, but multiple errors were observed ranging from typos to misleading practices. From a food safety perspective there is still a lot of improvement needed in the field of food supplements.
Ključne besede: trans-resveratrol, dietary supplements, food safety, regulation, labels, health claims, nutrition claims, novel foods, high-performance thin-layer chromatography, HPTLC
Objavljeno v DKUM: 15.04.2024; Ogledov: 199; Prenosov: 15
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Opis: Charge variants of therapeutic proteins are considered to be drug product variants and process-related impurities. To monitor charge heterogeneity, the development of a new analytical method is needed. Imaged capillary isoelectric focusing, capillary zone electrophoresis, and cation exchange chromatography assays were evaluated as candidate assays to support the early development of two new biological drug candidates. These are the analytical techniques most frequently used in the pharmaceutical industry for monitoring charge heterogeneity. We compared the advantages and disadvantages of these analytical techniques for monitoring charge variants in two innovative monoclonal antibodies. The results obtained revealed similarities and differences in the various analytical techniques. However, there is only a short time-frame dedicated to analytical method development when developing new biological drugs. With this in mind, imaged capillary isoelectric focusing showed a perfect balance between the quality and speed of analysis.
Ključne besede: Imaged capillary isoelectric focusing, capillary zone electrophoresis, cation exchange chromatography, charge variants, biological drug
Objavljeno v DKUM: 03.10.2023; Ogledov: 638; Prenosov: 43
Celotno besedilo (3,02 MB)

Opis: The LC-MS/MS method for determination of the anti-epileptic drug topiramate (TPM) in human plasma was developed and validated for pharmacokinetic and bioequivalence study purposes. For quantitative determination of TPM values the method with deuterated internal standard (topiramate-d12) and liquid chromatography with tandem mass spectrometry was used. TPM was extracted from the human plasma using the solid-phase extraction procedure on a Strata X extraction column. Negative ions were monitored in the selected reaction monitoring mode (SRM) and transitions m/z 338.2 > 78.2 and m/z 350.3 > 78.2 were used for the quantitative evaluation of TPM and the internal standard, respectively. The results obtained from validation were statistically evaluated according to the requirements of European Medicines Agency (EMA) and Food and Drug Administration (FDA) regulatory guidelines. The linearity of the method was checked within a concentration range from 10 to 2000 ng/mL. Successful validation confirmed that this method is precise, accurate, sensitive and therefore suitable for determination of topiramate plasma levels in pharmacokinetic and bioequivalence studies.
Ključne besede: topiramate, liquid chromatography tandem mass spectroscopy, human plasma, bioequivalence study
Objavljeno v DKUM: 18.08.2017; Ogledov: 1609; Prenosov: 103
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