Search results for "Elution"

Characterization of 1-aminocyclopropane-1-carboxylic acid oxidase from barley (Hordeum vulgare L.) seedlings and pine (Pinus sylvestris L.) needles

1999

Abstract Biochemical characteristics of 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase extracted from barley ( Hordeum vulgare L.) leaves and pine ( Pinus sylvestris L.) needles were investigated. ACC oxidase from barley leaves was soluble while for complete recovery of ACC oxidase from pine needles addition of Triton X-100 to extraction medium was necessary. The enzyme required Fe 2+ , ascorbate and NaHCO 3 for maximum activity. A non-linear time course of ACC oxidase reaction indicated possible catalytic inactivation of the enzyme. The maximum activity was measured at pH 7.0–7.2 for ACC oxidase from both barley leaves and pine needles. The apparent K m for ACC was found to be 77 and …

Super-high-speed liquid chromatography of proteins and peptides on non-porous Micra NPS-RP packings

1999

Abstract The new generation of non-porous silica RP packings commercially available from Micra Scientific was tested for separations of peptides and proteins by means of the gradient HPLC. Extremely high-speed separations were achieved using conventional chromatographic equipment: six proteins could be completely separated within six seconds. Tryptic digest peptides could be resolved in more then 40 components within 2–3 min. The effect of the experimental parameters such as temperature, flow rate etc. was investigated.

Fractal calibration in size-exclusion chromatography

2003

Abstract The elution behaviour of different polymer–solvent systems in three types of organic columns for SEC has been compared and interpreted. The experimental data show that the classical universal calibration is not accomplished. Deviations from a unique curve are observed due to the binary and ternary interactions between the components of the system (solvent, polymer and gel) which results on secondary mechanisms accompanying the main pure or “ideal” SEC separation mechanism. Both, enthalpic and entropic effects are interpreted in terms of the swelling and crosslinking degrees of the gel packings, and are also related with the fractal characteristics of their surfaces, such as the fra…

Multivalent ion-exchange model of biopolymer chromatography for mass overload conditions

1991

Abstract The simple model of multivalent ion-exchange biopolymer chromatography is analyzed on the basis of classical quasi-chemical temperature. The rigorous isotherm equation deduced from the stoichiometric displacement model (SDM) was used to stimulate the migration of a solute through the chromatographic column in the isocratic and gradient elution modes. The peak profiles generated for various sample sizes were compared with those obtained on the basis of a Langmuir isotherm. Peak tailing increases with the value of the exponent Z, defined as the ratio of the protein valency to the displacing counter-ion valency. For large Z the asymmetries due to the non-linearity of the isotherm are …

Single-pump heart-cutting two-dimensional liquid chromatography applied to the determination of fatty alcohol ethoxylates.

2014

Abstract A setup for heart-cutting bi-dimensional liquid chromatography (LC–LC), constructed with a chromatograph provided with a single pump, an auxiliary 6-port 2-position valve (V 6/2 ) and a column selector valve (V CS ), is described. The possible ways of connecting the two valves for LC–LC, namely with V 6/2 first followed by V CS and vice versa, are compared. The possibility of using the setups for preconcentration followed by the backwards transfer of the preconcentrated solutes to the detector or to a second column is also shown. The V 6/2 -first configuration for LC–LC was applied to the characterization of industrial fatty alcohol ethoxylates (FAEs) using UV–vis detection. For th…

Use of reversed-phase C18 Sep-Pak cartridges for the purification and concentration of sepiapterin and other pteridines

1985

Abstract Several pteridines have been tested for their ability to bind to C 18 Sep-Pak. Riboflavin, sepiapterin, deoxysepiapterin, 6-acetyl-7,8-dihydropterin, 6-acetyldihydrohomopterin and 3′-hydroxysepiapterin were strongly retained and all but 6-acetyldihydrohomopterin quantitatively recovered upon elution with 2 ml of methanol. The effect of the concentration and volume of the sample, pH and salt concentration on the retention of sepiapterin have been studied. The procedure was very useful for the purification, desalting, solvent exchange and concentration of pteridines having high affinity for the cartridge. C 18 Sep-Pak has been applied succesfully to sample clean-up prior to high-perf…

Polymer Retention Mechanism in GPC on Active Gels

1980

Abstract The elution behaviour of low molecular weight polystyrene (PS) down to the monomer on spherosil gel in several eluents has been studied. In the medium range of molecular weights the elution behaviour is similar to that followed by high molecular weight PS, the differences in elution volumes among different eluents increasing monotonically with decreasing molecular weight and partition rather than adsorption probably being responsible for the shifts in retention volumes. However, at the total permeation limit, the situation is alike to that found in liquid-solid chromatography, the elution volumes of solutes with molecular sizes very close to that of styrene being determined by solv…

Gelchromatographie. 1. Mitt. Trennung von oligomeren

1966

Vernetzte Polymere werden hergestellt und ihre Eignung zur gelchromatographischen Trennung von Gemischen von Oligomeren gepruft; im einzelnen wurden untersucht: mit Isocyanaten modifiziertes Sephadex; Polymethyl-und Polybutylmethacrylat, vernetzt mit Glykoldimethacrylat bzw. mit Polyathylenoxid-dimethacrylat; Polyvinylacetat, vernetzt mit n-Butandioldivinylather; Polystrol, vernetzt mit Divinylbenzol; ferner Silicagel. Der Einflus der Molekulgestalt auf das Elutionsvolumen wurde gepruft. Die Elutionsvolumina von p-Oligophenylenen, die eine stabchenformige Molekulgestalt besitzen, sind groser als die von Oligourethanen gleichen Molekulargewichts; o- und m-gewinkelte Oligophenylene zeigen geg…

1981

Elution curves on spherosil gels in pure and mixed eluents of poly(dimethylsiloxane), PDMS, and poly(methyl methacrylate), PMMA, as well as those of polystyrene, PS, just for comparison, have been determined. In a general way, PDMS elution volumers fit to those of PS, whereas PMMA elution curves shift to higher retention volumes. The differences in retention volumes between the different polymeric solutes have been interpreted in terms of differences in polymer-gel and polymer-solvent interactions. Hydrogen-bonding seems to be the main contribution to solute-substrate interactions.

Bestimmung von Tri-n-butylphosphat in Plasmapräparaten nach Festphasenextraktion und Kapillar-Gaschromatographie

1988

A simple method for the quantitative determination of tri-n-butylphosphate in blood plasma preparations is described. The sample is passed through an octadecyl extraction column from which tri-n-butylphosphate is eluted with chloroform. By capillary GC 50 micrograms/l tri-n-butylphosphate can be detected with a recovery of more than 90%.