Search results for "ROMA"

Interpretive search of optimal isocratic and gradient separations in micellar liquid chromatography in extended organic solvent domains

2020

Abstract Micellar liquid chromatography (MLC) is a reversed-phase mode with mobile phases containing an organic solvent and a micellised surfactant. Most procedures developed in MLC are implemented in the isocratic mode, since the general elution problem in chromatography is less troublesome. However, gradient elution may be still useful in MLC to analyse mixtures of compounds within a wide range of polarities, in shorter times. MLC using gradients is attractive to determine by direct injection moderate to low polar compounds in physiological samples. In these analyses, the use of initial micellar conditions (isocratic or gradient) with a fixed amount of surfactant above the critical micell…

Micellar Liquid Chromatography:  A Worthy Technique for the Determination of β-Antagonists in Urine Samples

1998

Several beta-antagonists (acebutolol, atenolol, celiprolol, labetalol, metoprolol, nadolol, propranolol) were determined in urine samples with fluorometric detection after direct injection, in less than 15 min, with a micellar mobile phase of 0.1 M sodium dodecyl sulfate (SDS), 15% propanol, and 1% triethylamine at pH 3. The limits of detection (38 criterion) were usually between 3 and 30 ng/mL. The addition of propanol and triethylamine and the reduction of the pH of the mobile phase improved the efficiency of the chromatographic peaks that was rather low in pure micellar eluents. The selection of the composition of the mobile phase was easily performed through the use of an interpretive p…

Performance of amines as silanol suppressors in reversed-phase liquid chromatography

2016

In reversed-phase liquid chromatography, cationic basic compounds yield broad and asymmetrical peaks, as a result of their ionic interaction with the anionic free silanol groups present in the silica-based stationary phases (commonly derivatised with C18 groups). A simple way to improve the peak shape is the addition to the hydro-organic mobile phase of a reagent (usually called additive) with cationic character. This associates with the stationary phase to prevent the access of analytes to the free silanol groups. Cationic additives may interact electrostatically with the anionic silanols. The hydrophobic region of the additive may also associate with the alkyl chains bound to the stationa…

New adsorbents for thymidylate synthase affinity chromatography

1988

New affinity adsorbents, intended for chromatography of thymidylate synthase (EC 2.1.1.45) from different sources, consisting of p-[N-[(2-amino-4-hydroxy-6-quinazolinyl)-methyl]-N-2-propynylamino]benzoyl-γ-[α-(3-carboxypropylamino)]glutamyl-glutamyl immobilized either on macroporous copolymer of acrylonitrile and n-butyl acrylate or on macroporous polymer of acrylonitrile itself, both crosslinked with divinylbenzene and having aminoethyl groups, were obtained. Both adsorbents were found to be effective in dUMP-dependent binding of thymidylate synthase from regenerating rat liver.

Magnetic In-Tube Solid Phase Microextraction

2012

We report a new in-tube solid phase microextraction approach named magnetic in-tube solid phase microextraction, magnetic-IT-SPME. Magnetic-IT-SPME has been developed, taking advantage of magnetic microfluidic principles with the aim to improve extraction efficiency of IT-SPME systems. First, a magnetic hybrid material formed by Fe(3)O(4) nanoparticles supported on SiO(2) was synthesized and immobilized in the surface of a bared fused silica capillary column to obtain a magnetic adsorbent extraction phase. The capillary column was placed inside a magnetic coil that allowed the application of a variable magnetic field. Acetylsalicylic acid, acetaminophen, atenolol, diclofenac, and ibuprofen …

Study and Modelling of the Vacuum Swing Adsorption (VSA) Process Employed in the Production of Oxygen

1999

An isothermal and non-equilibrium mathematical model was provided for the multi-component adsorption process. In addition, the software was developed for the VSA-based production of oxygen with the use of a CaX zeolite molecular sieve. The mathematical model and computer software were verified on the basis of experimental data. The study employed a test stand comprising two adsorption columns. The adsorption pressure P A = 150 and 135 kPa and desorption pressure P D = 20 kPa were adopted in the experiments. The tests produced oxygen with the purity of 90–94% O 2 (vol), at an efficiency of 55–73% and productivity of 570–850 kg O 2 per ton per day. The calculation results showed good consiste…

Zeolithe als Adsorbentien für die Trennung, Reinigung und Konzentrierung von organischen Wertprodukten in der präparativen Säulen-Flüssig-Chromatogra…

1995

Endometrial receptivity revisited: endometrial transcriptome adjusted for tissue cellular heterogeneity

2018

Study question Does cellular composition of the endometrial biopsy affect the gene expression profile of endometrial whole-tissue samples? Summary answer The differences in epithelial and stromal cell proportions in endometrial biopsies modify the whole-tissue gene expression profiles and affect the results of differential expression analyses. What is already known Each cell type has its unique gene expression profile. The proportions of epithelial and stromal cells vary in endometrial tissue during the menstrual cycle, along with individual and technical variation due to the method and tools used to obtain the tissue biopsy. Study design, size, duration Using cell-population specific trans…

New insights into the cellular makeup and progenitor potential of palatal connective tissues

2017

The present study investigated the regenerative potential of connective tissues harvested from two palatal areas widely used as donor sites for muco-gingival surgical approaches. Connective tissue grafts (CTGs) were obtained by de-epithelialisation of a free gingival graft (deCTG) and by a split flap approach from a previous donor site (reCTG). Two types of mesenchymal stem cell (MSCs) were isolated and were named de-epithelialised MSCs (deMSCs) and re-entry MSCs (reMSCs). The cells were characterised and cellular functionality was investigated. CTGs were evaluated using immunohistochemical and ultrastructural approaches. No significant differences were observed regarding the frequency of c…

Evaluation of the stromal vascular fraction of adipose tissue as the basis for a stem cell-based tissue-engineered vascular graft

2017

Abstract Objective One of the rate-limiting barriers within the field of vascular tissue engineering is the lengthy fabrication time associated with expanding appropriate cell types in culture. One particularly attractive cell type for this purpose is the adipose-derived mesenchymal stem cell (AD-MSC), which is abundant and easily harvested from liposuction procedures. Even this cell type has its drawbacks, however, including the required culture period for expansion, which could pose risks of cellular transformation or contamination. Eliminating culture entirely would be ideal to avoid these concerns. In this study, we used the raw population of cells obtained after digestion of human lipo…