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At least 631 records · Page 35Linked to original sources
PubMed2000

Precise analysis of primary amino acids in urine by an automated high-performance liquid chromatography method: comparison with ion-exchange chromatography.

A precise, simple and rapid method for the quantitative determination of primary amino acids in urine based on high-performance liquid chromatography and o-phthaldialdehyde pre-column derivatization is described. All primary urinary amino acids could be determined within 49 min (injection to injection). Amino acid concentrations in 40 urinary samples were measured by this method and the results were compared with those measured by ion-exchange chromatography. The correlation coefficient for the common amino acids was greater than 0.90. This is the first study in which such a detailed comparison has been made on urine samples. It appeared that the method described is an excellent alternative to the classical ion-exchange method for the quantitation of urinary amino acids.

Adolescent↗
PubMed1999

Prediction of protein retention at gradient elution conditions in ion-exchange chromatography.

This work presents a prediction procedure for protein retention in ion-exchange chromatography, where two linear gradient experiments of different length give the protein retention time at other linear gradients. The procedure predicts the retention time of early and late eluting proteins with similar precision and predictions by extrapolation deviate approximately 3% or less from the experimental retention times. By using the ionic strength, this procedure predicts protein retention times obtained with divalent ions in the eluent more accurately than a well-established procedure that uses the protein co-ion concentration.

Chromatography, Ion Exchange↗
PubMed2002

Gradient chromatofocusing. versatile pH gradient separation of proteins in ion-exchange HPLC: characterization studies.

A new chromatofocusing technique called gradient chromatofocusing is characterized. Gradient chromatofocusing generates linear pH gradients on anion-exchange columns with inexpensive low molecular mass buffer components via HPLC gradient mixing. Gradient chromatofocusing results are compared with that of conventional chromatofocusing in the chromatography of several proteins on a Mono P column, including beta-lactoglobulin A and B, ovalbumin, BSA, and conalbumin. Gradient chromatofocusing shows superior performance, with resolution increases greater than 3-fold being realized for the entire protein mixture and up to 25-fold for a particular protein pair. This performance superiority arises from inherent advantages in the gradient chromatofocusing technique in optimizing conditions pertinent to separation, including buffer concentration and pH gradient slope. These resolution gains arise from both increases in separation factor and decreases in peak width achieved with the pH gradient chromatofocusing technique through the manipulation of buffer concentration and the pH gradient profile. Gradient chromatofocusing is also compared with conventional NaCl gradient ion-exchange chromatography using the same Mono P column, demonstrating 3-fold resolution gains, resulting from a 3-fold decrease in peak width. The present work demonstrates the significantly improved performance that gradient chromatofocusing has in protein separations compared to other ion-exchange chromatographic techniques. Mechanisms for the various effects are discussed.

Animals↗
PubMed1989

Liquid ion-exchange chromatography under pressure of milk oligosaccharides using a pulsed amperometric detector.

Several oligosaccharides from human milk were separated completely on a Dionex AS6 ion-exchange column under mild alkaline conditions, such that no degradation of oligosaccharides was detectable after incubation for 6 h at room temperature in the eluent buffer. In general, both the presence of fucosyl groups and branching within oligosaccharide chains tend to reduce retention times for oligosaccharides in this system. Thus, both lacto-N-fucopentaose II [beta-D-Galp-(1----3)-[alpha-L-Fucp-(1----4)]-beta-D-GlcpNAc-(1--- -3)- beta-D-Galp-(1----4)-D-Glc] and lacto-N-fucopentaose III [beta-D-Galp-(1----4)-[alpha-L-Fucp-(1----3)]-beta-D-GlcpNAc-(1--- -3)- beta-D-Galp-(1----4)-D-Glc] were eluted before lacto-N-fucopentaose I [alpha-L-Fucp-(1----2)-beta-D-Galp-(1----3)-beta-D-GlcpNAc-(1----3 )-beta-D- Galp-(1----4)-D-Glc], and all three fucopentaoses were eluted earlier than lacto-N-tetraose [beta-D-Galp-(1----3)-beta-D-GlcpNAc-(1----3)-beta-D-Galp-(1----4)-D-Glc ]. 2'-Fucosyllactose [alpha-L-Fucp-(1----2)-beta-D-Galp-(1----4)-D-Glc] and 3-fucosyllactose [alpha-D-Galp-(1----4)-[alpha-L-Fucp-(1----3)]-D-Glc] were separated completely under a wide range of conditions. Introduction of substituents at either the O-3 or O-4 of 2-acetamido-2-deoxy-D-glucose produced large differences in retention: lacto-N-tetraose and lacto-N-neotetraose [beta-D-Gal-(1----4)-beta-D-GlcpNAc-(1----3)-beta-D-Galp-(1----4)-D-Glc] could be separated by more than 8 min. The l.c. ion-exchange chromatographic system described represents a useful addition to existing methods for separating oligosaccharides derived from glycoproteins and glycolipids.

Asialoglycoproteins↗
PubMed1984

Pseudohypoaldosteronism in a child with Down syndrome. Long-term management of salt loss by ion exchange resin administration.

At 4 weeks of age, an infant with Down syndrome developed severe dehydration and salt loss with the typical features of pseudohypoaldosteronism (PHA). Plasma renin activity, 11-deoxycorticosterone, corticosterone and aldosterone levels were all increased several-fold over the normal range for age, thus excluding an adrenal biosynthetic defect. Clinical condition, hyponatraemia and hyperkalaemia could be rapidly normalised by the ion exchange resin Resonium A administered first as enema and later orally (3 g/day). At that time, no further salt supplementation was necessary. At 18 months of age, Resonium A could be completely withdrawn with neither clinical deterioration nor electrolyte abnormalities. However at 3 1/2 years of age, plasma renin activity and aldosterone were still markedly elevated while precursor steroids were normal and the clinical condition satisfactory. No side effects were observed with the Resonium A therapy. The combination of trisomy 21 and PHA is very unusual. Similarly, the successful treatment of severe renal salt loss during infancy by sodium supplementation and concomitant potassium withdrawal via an oral ion exchange resin has not yet been described and warrants further therapeutic trials.

Aldosterone↗
PubMed1978

Qualitative detection of placidyl (ethchlorvynol) alone or in combination with poly-drugs in drug abuse urine screening programs using ion-exchange paper and/or liquid-liquid extraction.

Two procedures for the detection of ethchlorvynol are presented. Procedure I involves the use of SA-2-cation-exchange resin loaded paper. The use of multiple ion-exchange resin papers is proposed in a sequence that enables the detection of amphetamines, barbiturates, phenothiazines, propoxyphene (Darvon), phencyclidine, cocaine (benzoyl ecgonine), pentazocine (Talwin) and benzodiazepines in addition to ethchlorvynol. This procedure discusses the details of detecting ethchlorvynol in combination with the entire array of drugs of abuse depending on the needs of a clinical program. Procedure II involves the principle of liquid-liquid extraction using either raw or spent urines.

Chromatography, Ion Exchange↗
PubMed2000

[Determination of palladium by ion exchange resin phase spectrophotometry].

A new method for the determination of palladium by ion exchange resin phase spectrophotometry has been established. It is based on the fixation of palladium as 1-(5-bromo-2-phridylazo)-2-naphthol-6-sulphonic acid (5-Br-PAN-S) compelled on a anion-exchange resin. The resin phase absorbances at 690 and 800 nm are measured directly and the linear range of 0-20 micrograms for palladium. The method has been applied to the determination of palladium in water samples and catalysts with satisfactory results.

Ion Exchange Resins↗
PubMedDate not supplied

[Method of purification of water by means of ion-exchange cellulose fibers].

A new method of and an arrangement for continuous ion-exchange purification of water from admixtures contained therein in the form of dissolved electrolyte ions have been devised. As a basic working element for this purpose serves anion-exchange tape made of anion-exchange cellulose fibre (ICF) that enables a continuous purification of water from impurities contained therein the be effected as needed.

Cellulose↗
PubMed2006

The application and properties of composite sorbents of inorganic ion exchangers and polyacrylonitrile binding matrix.

A description is given of the preparation and properties of potassium hexacyanocobalt (II) ferrate (II) (KCFC) and the composite, potassium hexacyanocobalt (II) ferrate (II)-polyacrylonitrile (KCFC-PAN). The materials were dried at high temperatures and characterized by chemical analysis, scanning electron microscope, X-ray diffraction, inductively coupled plasma and infrared. The ion exchange of alkaline earth metals and molybdenum on a nonstoichiometric compound K(2)[CoFe(CN)(6)] and its PAN based absorber was examined by batch methods. The adsorption of molybdenum from aqueous solutions on KCFC-PAN was investigated and optimized as a function of equilibration time and pH. The materials which were dried at optimum high temperature of 110 degrees C were found to be stable in water, dilute acids, alkaline solutions and relatively high temperature. The distribution coefficient values K(d) for alkaline earth metals, followed the same trend of increase for both sets of absorbers studied, i.e. Ba(2+)>Sr(2+)>Ca(2+)>Mg(2+), which closely resembles to the order of the size of the hydrated cations. However, the K(d) values show a significant increase for PAN based absorbers in comparison to KCFC absorbers.

Acrylic Resins↗
PubMed1996

Determination of amino acids in the foods by reversed-phase high-performance liquid chromatography with a new precolumn derivative, butylthiocarbamyl amino acid, compared to the conventional phenylthiocarbamyl derivatives and ion-exchange chromatography.

A new derivatizing reagent, butylisothiocyanate (BITC), reacts quantitatively with the 22 standard amino acids and the amino acids in the acid hydrolysate of food and the protein standard, bovine serum albumin (BSA), at 40 degrees C for 30 min to yield butylthiocarbamyl (BTC) amino acids. The sensitivity of BTC-amino acid was similar to phenylthiocarbamyl (PTC) amino acid. The detection limit in both derivatives was about 3.9 pmol at 0.05 AUFS that showed a stable baseline for the quantitative determination. Analysis of the results obtained with BSA and food samples as BTC derivatives showed good agreement with those determined as PTC derivatives, ion-exchange chromatography and data presented in the literatures, except for a few amino acids. Especially the values compared to those of ion-exchange chromatography were very close, except for histidine. The advantage of the BITC reagent over the phenylisothiocyanate was that it had high volatility, so the excess reagent and by-products were removed in about 10 min, compared to about 1 h in the PITC reagent, with a common aspirator. In the BTC derivatives, cystine and cysteine were determined separately but in the PTC derivatives they were resolved into a single peak.

Amino Acids↗
PubMed1992

Enantiomeric separations using bovine serum albumin immobilized on ion-exchange stationary phases.

Bovine serum albumin (BSA) can be readily immobilized on ion-exchange stationary phases by frontal analysis of a proper solution. This provides a simple means of adjusting the amount of BSA contained in the column and of measuring it accurately. Although the immobilization is ionic and not covalent, the columns are stable for extensive periods of time. If needed, they can be easily regenerated by the same frontal analysis procedure.

Animals↗
PubMed1965

THE NON-STEADY STATE MEMBRANE POTENTIAL OF ION EXCHANGERS WITH FIXED SITES.

A system of equations, based upon the assumption that the only force acting on each ionic species is due to the gradient of its electrochemical potential, is used to deduce, in the non-steady state for zero net current, the expression of the difference of electric potential between two solutions separated by an ion exchange membrane with fixed monovalent sites. The membrane is assumed to be solely permeable to cations or anions, depending on whether the charge of the sites is -1 or +1, and not to permit any flow of solvent. Under the assumptions that the difference of standard chemical potentials of any pair of permeant monovalent species and the ratio of their mobilities are constant throughout the membrane, even when the spacing of sites is variable, explicit expressions are derived for the diffusion potential and total membrane potential as functions of time and of solution activities. The expressions are valid for any number of permeant monovalent species having ideal behavior and for two permeant monovalent species having "n-type" non-ideal behavior. The results show that for a step change in solution composition the observable potential across a membrane having fixed, but not necessarily uniformly spaced, sites becomes independent of time once equilibria are established at the boundaries of the membrane and attains its steady-state value even while the ionic concentration profiles and the electric potential profile within the membrane are changing with time.

Biophysical Phenomena↗
PubMed1991

Separation of some platinum(II) complexes by ionic strength gradient on a solvent-generated ion-exchange sorbent.

The compatibility of ionic strength gradient with solvent-generated ion-exchange chromatography on an octadecylsilica sorbent was proven for a mobile phase containing octanesulphonate. Only a slight baseline shift was observed during the gradient of the phosphate buffer, even at 210 nm. An equilibration time of 3 min between the runs was sufficient to obtain retention times with a reproducibility better than 1%. The compounds separated were cisplatin, carboplatin and related neutral and cationic platinum(II) complexes, including transplatin and the aquation products of cisplatin.

Carboplatin↗