Search results for "high performance liquid chromatography"
showing 10 items of 20 documents
Fenibuta piemaisījumu kvantitatīvas noteikšanas metodes optimizācija un validācija
2021
Kokina. P., zinātniskie vadītāji: Dr. ķīm. V. Bartkevičs (LU), Dr. ķīm. A. Bolotin (AS Olainfarm). Maģistra darbs, 147 lappuses, 184 attēli, 75 tabulas, 15 literatūras avoti, 16 pielikumi. Latviešu valodā. Maģistra darbā ir veikta divu piemaisījumu(4-amino-3-fenilbutānskābes etilestera hidrohlorīds un 4-fenil-2-pirrolidons) kvantitatīvas noteikšanas analīzes metodes optimizācija un validācija farmaceitiskā preperāta Noofen® aktīvajai farmaceitiskai vielai (AFV) fenibuts. Metodes optimizācija un validācija bija nepieciešama farmaceitiskā preparāta Noofen® kvalitātes kontroles vajadzībām. Fenibuta paraugi tika analizēti ar augsti efektīvo šķidruma hromatogrāfiju (AEŠH). Optimizācija tika vērs…
Novel multimetabolite prediction of walnut consumption by a urinary biomarker model in a free-living population: the PREDIMED study.
2014
The beneficial impact of walnuts on human health has been attributed to their unique chemical composition. In order to characterize the dietary walnut fingerprinting, spot urine samples from two sets of 195 (training) and 186 (validation) individuals were analyzed by an HPLC-q-ToF-MS untargeted metabolomics approach, selecting the most discriminating metabolites by multivariate data analysis (VIP ≥ 1.5). Stepwise logistic regression analysis was used to design a multimetabolite prediction biomarker model. The global performance of the model and each included metabolite in it was evaluated by receiver operating characteristic curves, using the area under the curve (AUC) values. Dietary expos…
Liquid chromatography in pharmaceutical analytics
2017
Tutkielmassa perehdytään nestekromatografian käyttöön lääkeaineanalytiikassa. Korkean erotuskyvyn nestekromatografia (HPLC) on suosittu menetelmä lääkeaineiden analysoinneissa, esimerkiksi pitoisuuksien tai epäpuhtauksien määrityksissä. HPLC-menetelmät voidaan luokitella useisiin alalajeihin ja käänteisfaasinestekromatografia (RP-HPLC) on niistä suosituin lääkeaineanalytiikassa. Tässä kirjallisuuskatsauksessa käsitellään erityisesti nopeaa nestekromatografiaa. Analyysimenetelmiä voidaan nopeuttaa sopivan kolonnin avulla. Tavanomainen HPLC-ajo on mahdollista toteuttaa lyhyemmässä ajassa käyttämällä lyhyttä kolonnia tai kolonnia, jossa partikkelikoko on pieni. Kuitenkin tehokkain tapa on käyt…
Effect of Sunlight Exposure on Anthocyanin and Non-Anthocyanin Phenolic Levels in Pomegranate Juices by High Resolution Mass Spectrometry Approach
2020
Quali-quantitative analyses of anthocyanins and non-anthocyanin phenolic compounds performed with the use of liquid chromatography coupled with high resolution mass spectrometry, were evaluated in juice of pomegranate fruits (&lsquo
Science based calibration for the extraction of 'analyte-specific' HPLC-DAD chromatograms in environmental analysis
2010
Multivariate science based calibration (SBC) has been applied to the resolution of overlapped peaks in liquid chromatography with diode array detection (LC-DAD). Complex river water samples spiked with 11 pharmaceutical substances resulted in poorly resolved chromatograms containing additional peaks from interfering matrix compounds and a change in the background absorbance due to the mobile phase gradient. Applying the present multivariate approach it was possible to resolve all 11 analytes from overlapping peaks, obtaining linear calibration lines (R2 > 0.96). Recovery percentages on spiked samples ranged between 74.6 and 113.5%, which are quite satisfactory taking into account the low co…
No evidence of ATP1A2 involvement in 12 multiplex Italian families with benign familial infantile seizures
2005
A missense mutation in the gene encoding the alpha(2) Subunit of the Na+,K+ ATPase pump (ATP1A2) was found in a family with both familial hemiplegic migraine (FHM) and Benign Familial Infantile Seizures (BFIC). As it is still unclear whether ATP1A2 is responsible for pure BFIC syndromes, we checked mutations of the ATP1A2 gene in probands of 12 Italian multiplex families with pure BFIC, who were negative for mutations in the SCN2A gene. We screened the ATP1A2 gene by denaturing high performance liquid chromatography (D-HPLC) and direct sequencing of DNA fragments showing an aberrant elution pattern. We found one exonic variant and five intronic variants, none leading to significant amino ac…
Modulation of the growth and metabolic response of cyanobacteria by the multifaceted activity of naringenin
2017
The interactions between the plant-derived bioflavonoid, naringenin, and prokaryotic microalgae representatives (cyanobacteria), were investigated with respect to its influence on the growth and metabolic response of these microorganisms. To achieve reliable results, the growth of cyanobacteria was determined based on measurements of chlorophyll content, morphological changes were assessed through microscopic observations, and the chemical response of cells was determined using liquid and gas chromatography (HPLC; GC-FID). The results show that micromolar levels of naringenin stimulated the growth of cyanobacteria. Increased growth was observed for halophilic strains at naringenin concentra…
Light-induced Changes in the Dimerization Interface of Bacteriophytochromes
2015
Phytochromes are dimeric photoreceptor proteins that sense red light levels in plants, fungi, and bacteria. The proteins are structurally divided into a light-sensing photosensory module consisting of PAS, GAF, and PHY domains and a signaling output module, which in bacteriophytochromes typically is a histidine kinase (HK) domain. Existing structural data suggest that two dimerization interfaces exist between the GAF and HK domains, but their functional roles remain unclear. Using mutational, biochemical, and computational analyses of the Deinococcus radiodurans phytochrome, we demonstrate that two dimerization interfaces between sister GAF and HK domains stabilize the dimer with approximat…
A critical size for emergence of nonbulk electronic and geometric structures in dodecanethiolate-protected Au clusters.
2014
We report on how the transition from the bulk structure to the cluster-specific structure occurs in n-dodecanethiolate-protected gold clusters, Au(n)(SC12)m. To elucidate this transition, we isolated a series of Au(n)(SC12)m in the n range from 38 to ∼520, containing five newly identified or newly isolated clusters, Au104(SC12)45, Au(∼226)(SC12)(∼76), Au(∼253)(SC12)(∼90), Au(∼356)(SC12)(∼112), and Au(∼520)(SC12)(∼130), using reverse-phase high-performance liquid chromatography. Low-temperature optical absorption spectroscopy, powder X-ray diffractometry, and density functional theory (DFT) calculations revealed that the Au cores of Au144(SC12)60 and smaller clusters have molecular-like elec…
Application of a low transition temperature mixture for the dispersive liquid–liquid microextraction of illicit drugs from urine samples
2021
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