Search results for " HPLC"

Reliable and simple analytical methods for determination of citrulline and metabolically related amino acids by liquid chromatography after derivatiz…

2014

We describe the development of a high-performance liquid chromatography (HPLC) method for the determination of citrulline and other amino acids relevant to intestinal diseases. The amino acids were derivatized with 9-fluorenylmethylchloroformate (FMOC-Cl) and their derivatives were separated on two different columns, a core-shell column (Halo C18) and a silica-based monolith (Chromolith Performance RP-18). The derivatization reaction was optimized with respect to pH, buffer concentration and reproducibility. The optimal derivatization conditions were achieved with 0.4 M borate buffer at pH 9.20, a constant ratio of FMOC-Cl/total amino acids (10 : 1) and 75 mM tyramine after 1 min (quenching…

Identification and quantification of valuable phenolic compounds from red wines from western part of Romania

2019

The aim of this paper is to identify and quantify different phenolic compounds known and appreciated for their antioxidant action from five red wines from the west side of Romania. For the determinations HPLC methods were used, the samples were done in cycles of three for better results. Phenolic acids that drew the attention have different values that ranging from 1.3007 mg/L (elagic acid) to 19.3315 (t-cafftaric acid), some various flavonoids (flavone, flavonoli și flavanoli) the values of which were recorded between 0.9997 mg/L (apigenin) and 56.1617 mg/L (catechin) and the stilbens namely the resveratrol has reached the maximum value of 8.1427 mg/L. The phenolic compounds that were det…

Methacrylate ester-based monolithic columns for nano-LC separation of tocopherols in vegetable oils

2010

The separation and determination of tocopherols (Ts) in vegetable oils by nano-LC chromatography with UV-vis detection using lauryl methacrylate ester-based monolithic columns has been developed. The separation of Ts was optimized in terms of mobile phase composition on the basis of the best compromise among efficiency, resolution and analysis time. Using a mobile phase composed of ACN/methanol/water, an excellent resolution between Ts was achieved within 18 min. The LODs were lower than 0.26 μg/mL, being repeatability values of retention time and peak area below 0.15 and 3.1%, respectively. The method was applied to the quantification of Ts and tocotrienols present in several vegetable oil…

Stereoselective Synthesis and Pharmacological Evaluation of 2,4-Bridged Piperidine Derivatives Designed to Activate the κ-Opioid Receptor

2021

The effect of the pore structure and zeta potential of porous polymer monoliths on separation performance in ion-exchange mode.

2007

Most often, in bioseparations involving charged macromolecules, the chromatographic systems have low Reynolds and high Peclet numbers. For such systems, an expression is developed and presented in this work for evaluating the throughput in polymeric monoliths where ion-exchange adsorption occurs, as a function of (i) the pressure drop along the length of the monolith, (ii) the functional form and width of the throughpore-size distribution of the monolith, and (iii) the magnitude of the zeta potential on the surface of the throughpores of the monolith. Gaussian and log-normal throughpore-size distributions whose mean throughpore-size and standard deviation values are based on experimentally …

Chiral gamma-lactones from Fusarium poae: enentiomeric ratios and sensory differentiation of cis-6-gamma-dodecenolactone enantiomers

1991

Chiral gamma-lactones from Fusarium poae: enentiomeric ratios and sensory differentiation of cis-6-gamma-dodecenolactone enantiomers

Photografted methacrylate-based monolithic columns coated with cellulose tris(3,5-dimethylphenylcarbamate) for chiral separation in CEC

2018

A chiral capillary monolithic column for enantiomer separation in capillary electrochromatography was prepared by coating cellulose tris(3,5-dimethylphenylcarbamate) on porous glycidyl methacrylate-co-ethylene dimethacrylate monolith in capillary format grafted with chains of [2(methacryloyloxy)ethyl] trimethylammonium chloride. The surface modification of the monolith by the photografting of [2(methacryloyloxy)ethyl] trimethylammonium chloride monomer as well as the coating conditions of cellulose tris(3,5-dimethylphenylcarbamate) onto the grafted monolithic scaffold were optimized to obtain a stable and reproducible chiral stationary phase for capillary electrochromatography. The effect o…

Gender-related variations in hemolymph parameters of Carabus lefebvrei (Coleoptera: Carabidae): HPLC analysis and phenoloxidase activity

2017

We characterized the enzymatic activity of basal and total phenoloxidase and HLPC and SDS- PAGE profiles in hemolymph of Carabus lefebvrei males and females at different reproductive status. The phenoloxidase activity was activated by trypsin and inhibited by phenoloxidase activity specific inhibitor phenylthiourea. Our results demonstrated that both in males and females, there were no significant differences in the basal phenoloxidase activity between reproductive and virgin beetles, while the total phenoloxidase activity increased significantly in virgin specimens. Thus, resources seem to be invested to increase the humoral response in pre-reproductive phase forming a barrier against path…

Characterization of the synthetic cannabinoid MDMB-CHMCZCA

2016

The synthetic cannabinoid MDMB-CHMCZCA was characterized by various spectroscopic techniques including NMR spectroscopy and tandem mass spectrometry. The synthetic sample was found to be of S-configuration by VCD spectroscopy and comparison of the data with DFT calculations, while ECD spectroscopy was found to be inconclusive in this case. The enantiomeric purity of samples from test purchases and police seizures was assessed by a self-developed chiral HPLC method.

COMPARAZIONE DEI PROFILI METABOLICI DI VARIETÀ DI CILIEGIO DOLCE (Prunus avium L.) MEDIANTE TECNICHE DI METABOLOMICA UNTARGETED

La diffusione di cultivar altamente produttive ha influito negativamente sulla tutela dell’agro-biodiversità di Prunus avium L. determinando disinteresse nei confronti di varietà meno produttive ma meritevoli di attenzione per il valore delle loro caratteristiche organolettiche e del relativo patrimonio genetico. Il mondo scientifico ha mostrato interesse nei confronti di tale tematica e ha condotto azioni di conservazione in situ ed ex situ per preservare il germoplasma ancora esistente. La presente ricerca analizza l’agrobiodiversità del ciliegio dolce in relazione alla diversa composizione metabolomica dei frutti, espressione del genotipo che le caratterizza. L’attività di ricerca svolta…