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PubMed1979

An ion-exchange assay for high molecular weight alkaline phosphatase.

An ion-exchange method for the measurement of a high molecular weight form of alkaline phosphatase in serum is described. The method is simple, rapid, precise and suitable for processing small batches of samples. Other forms of alkaline phosphatase commonly encountered in serum do not interfere. The correlation between results obtained by this method and those obtained by Sephadex 6B chromatography is discussed. Electrophoretic methods of measurement were also investigated but were found to be both imprecise and inaccurate.

Alkaline Phosphatase↗
PubMed2006

Advances in cement solidification technology for waste radioactive ion exchange resins: a review.

Treatment and disposal of waste radioactive ion exchange resins is one of the most urgent problems for nuclear industries in China. Cement solidification technology has many advantages, such as requiring simple equipment, easy scaling-up, low working temperature, no trouble of gas cleaning and low cost. It is a suitable technology for treatment of waste radioactive resins, and has been widely used. The new developments and theoretical basis of cement solidification of radioactive resins were introduced in this paper. The cement solidification technology suitable for China and the questions needed to solve were also discussed.

Hot Temperature↗
PubMed2001

Water structures in ion-exchange resin particles: solvation dynamics of Nile Blue A.

The structures of water, partitioned in cation-exchange resin particles, were studied on the basis of fluorescence dynamics of Nile Blue A (NB). The fluorescence lifetime of NB in the resin was longer than that in water and increased with increasing cross-linking density of the resin (rho). The results demonstrated that the water structures in the resin were significantly different from those in water and dependent on rho. A study on solvation dynamics of NB in the resin, reflecting structured water around the ion-exchange group, revealed the roles of "bound water" molecules in the water structures, since the solvent relaxation time (tauS) in the resin was much longer than that in water and depended on p; tauS increased from 34 to 55 ps with increasing rho from 2 to 8%. The origin of the rho dependence of tauS was discussed in terms of the separation distance between the ion-exchange groups, and the effects of the counterion of the ion-exchange group on the solvation processes were also discussed.

Journal Article↗
PubMed2001

Analysis of sulfonated compounds by ion-exchange high-performance liquid chromatography-mass spectrometry.

Ion-exchange high-performance liquid chromatography (HPIEC)-mass spectrometry (MS) was used for the analysis of different sulfonated compounds. HPIEC was performed on an aminopropyl column applying a gradient with increasing concentration of a buffer consisting of ammonium acetate-acetic acid and acetonitrile as the organic modifier. HPIEC is well suited to highly efficient separation of sulfonated compounds and furthermore, due to the volatility of ammonium acetate, the method is also appropriate for LC-MS coupling by the means of either atmospheric pressure chemical ionization or electrospray ionization. The applicability range of HPIEC-MS is demonstrated on the basis of a complex mixture of model substances consisting of sulfonated aromatics and textile dyes largely differing from each other in their structural properties.

Chromatography, High Pressure Liquid↗
PubMed1987

Purification of human thyroid peroxidase using ion exchange liquid chromatography.

We have utilized a one step ion-exchange (FPLC Mono Q) purification procedure for the isolation of human thyroid peroxidase (TPO). The purified TPO had the properties of a major microsomal antigen and inhibited the binding of human microsomal autoantibodies to thyroid microsomal membranes. The isolated TPO was free from thyroglobulin and showed, compared with crude microsomal proteins, a reduced background binding with control sera in enzyme-linked immunoassay (ELISA). SDS-gel electrophoresis of the isolated TPO detected one major band with an apparent molecular weight of 105 kD. The antigenicity of the protein was demonstrated by immunoblotting using sera from patients with autoimmune thyroiditis. These results demonstrate that FPLC Mono Q chromatography offers a rapid, quantitative and precise method for large scale purification of TPO with retained enzymatic and antigenic activity for use in ELISA and for further studies on the structure and function of this protein.

Autoantibodies↗
PubMedDate not supplied

Ion exchange membrane bioreactor for selective removal of nitrate from drinking water: control of ion fluxes and process performance.

An ion exchange membrane bioreactor (IEMB), consisting of a monoanion permselective membrane dialyzer coupled to a stirred anoxic vessel with an enriched mixed denitrifying culture, has been studied for nitrate removal from drinking water. The influence of nitrate and chloride concentrations on the selectivity of nitrate transport in the IEMB process was investigated. With appropriate dosing of chloride ions to the IEMB biocompartment, it was possible to regulate the net bicarbonate flux in the system, thus maintaining the bicarbonate concentration in the treated water at the desired level. The latter was not possible to achieve in Donnan dialysis, operated as a single process in which, besides the lower nitrate removal efficiency found, bicarbonate was co-extracted together with nitrate from the polluted water stream. Residual carbon source (ethanol) and nitrite were not detected in the treated water produced in the IEMB system. With a concentration of nitrate in the polluted water three times higher than the maximum contaminant level of 50 mg L(-1) allowed, the IEMB process was successfully operated for a period of 1 month before exceeding this limit.

Biofilms↗
PubMed2004

Fractionation of whey proteins with high-capacity superparamagnetic ion-exchangers.

In this study we describe the design, preparation and testing of superparamagnetic anion-exchangers, and their use together with cation-exchangers in the fractionation of bovine whey proteins as a model study for high-gradient magnetic fishing. Adsorbents prepared by attachment of trimethyl amine to particles activated in sequential reactions with allyl bromide and N-bromosuccinimide yielded a maximum bovine serum albumin binding capacity of 156 mg g(-1) combined with a dissociation constant of 0.60 microM, whereas ion-exchangers created by linking polyethylene imine through superficial aldehydes bound up to 337 mg g(-1) with a dissociation constant of 0.042 microM. The latter anion-exchanger was selected for studies of whey protein fractionation. In these, crude bovine whey was treated with a superparamagnetic cation-exchanger to adsorb basic protein species, and the supernatant arising from this treatment was then contacted with the anion-exchanger. For both adsorbent classes of ion-exchanger, desorption selectivity was subsequently studied by sequentially increasing the concentration of NaCl in the elution buffer. In the initial cation-exchange step quantitative removal of lactoferrin (LF) and lactoperoxidase (LPO) was achieved with some simultaneous binding of immunoglobulins (Ig). The immunoglobulins were separated from the other two proteins by desorbing with a low concentration of NaCl (< or = 0.4 M), whereas lactoferrin and lactoperoxidase were co-eluted in significantly purer form, e.g. lactoperoxidase was purified 28-fold over the starting material, when the NaCl concentration was increased to 0.4-1 M. The anion-exchanger adsorbed beta-lactoglobulin (beta-LG) selectively allowing separation from the remaining protein.

Adsorption↗
PubMed1998

Preparative ion-exchange chromatography of proteins from dairy whey.

A preparative-scale ion-exchange chromatographic process is described for the separation of the four major proteins and lactose from sweet dairy whey. Experiments using a commercial anion-exchange resin were carried out to determine the optimum conditions for initially separating the proteins alpha-lactalbumin, beta-lactoglobulin, bovine serum albumin, immunoglobulin G and lactose from a sweet dairy whey mixture. The separation was accomplished with simultaneous step elution changes in salt concentration and pH. It was found that the anion-exchange step was most effective in separating beta-lactoglobulin from the feed mixture. Following the anion-exchange separation, its breakthrough curve was processed using a commercial cation-exchange resin to further recover the valuable immunoglobulin G. The whey output from an east Tennessee cheese manufacturer was used as a feedstream for the preparative scale experiments and as a reference in scaling to an economically optimized production level operation.

Animals↗
PubMed1997

Generation of Light-Induced Electrical Potential from Ion Exchange Membranes Containing 4,4'-Bipyridine Moiety

The effect of various swelling solvents for anion exchange membranes having a viologen moiety as the anion exchange groups on photovoltage was examined to obtain a high photovoltage and to clarify the mechanism of charge transfer. Anion exchange membranes having a viologen moiety, based on a copolymer membrane of chloromethylstyrene and divinylbenzene and a film of chloromethylated polysulfone, were swelled with various solvents, and clamped between two ITO electrodes (indium-tin oxide electrodes), and a xenon lamp irradiated the membrane from one side. In general, the solvents that swelled the membranes well and provided a high photovoltage included ethylene glycols, 1,3-dioxolane, 1,3-dioxane, and 1-methyl-2-pyrrolidone. Especially, the membrane swelled with 1,3-dioxolane generated a high photovoltage. It is thought from these results that methylene groups neighboring oxygen and between two oxygens, which is an electron acceptor, are related to the charge transfer in the system. When the cell was assembled by sandwiching a cation exchange membrane (as a separator) between two anion exchange membranes with a viologen moiety, the photovoltage significantly decreased with an increase in repeat time of the irradiation and interruption. On the other hand, the voltage of the cell having of an anion exchange membrane separator did not significantly decrease with the same procedure. When non-ion-exchanged chloride ions were added to the cell, the generation of the photovoltage became high compared to the cell without the ions. It was concluded from these results that chloride ions also play an important role in the charge transfer in the cell.

Journal Article↗
PubMed1997

Calibration of ion-exchange HPLC measurements of glycohemoglobin: effect on interassay precision.

To investigate the effect of calibration with lyophilized calibrators on the interassay precision of glycohemoglobin (glyHb) measurements, we used an ion-exchange HPLC system equipped with a Pharmacia Mono S HR 5/5 column. Calibration of analytical runs substantially increased interassay variation (CV), from 1.7% to 4.4% and from 0.9% to 3.2% for control samples with low (6.5%) and high (14%) glyHb percentages, respectively. Standardization of glyHb results, though essential for interlaboratory comparisons, should not be done at the expense of assay precision, as may occur with thoughtless use of lyophilized calibrators. We therefore recommend the use of carefully determined conversion factors for standardization of glyHb results obtained with ion-exchange HPLC systems that are capable of excellent long-term interassay precision.

Calibration↗
PubMed1975

Ion exchange tempering of glass ophthalmic lenses.

We performed low velocity drop-ball tests using 5/8-, 7/8-, and 1-inch diameter steel balls on ophthalmic crown glass lenses chemically tempered by the ion exchange process. Four representative dioptric strengths (+ 2.50 spherical, - 2.50 spherical, -2.50 cylindrical, and plano) were studied with the isolated lenses mounted, convex side up, on the American National Standards Institute Z80 test block. New ion exchange lenses exhibited a 100 to 350% greater capacity for attenuation of energy from low velocity, large size missiles than matched lenses of similar strength prepared by the conventional heat-treating and air-quenching process.

Eye Injuries↗
PubMed2005

[Separation and purification of PEGylated rhG-CSF by two-step ion-exchange chromatography].

In order to separate and purify the PEGylated recombinant human granulocyte stimulating factor (rhG-CSF) at large laboratory-scale level, a two-step ion-exchange chromatographic separation procedure was designed. Cation-exchange chromatography was applied first to separate PEGylated rhG-CSF from un-reacted rhG-CSF, followed by anion-exchange chromatography to dissolve individual PEG-rhG-CSF species (mono-, di- and tri-PEGylated rhG-CSF) and remove the free PEG. The molecular weight of individual PEGylated rhG-CSF was determined by MALDI-TOF and SDS-PAGE. MALDI-TOF mass spectrometry revealed that the molecular weights of mono-, di- and tri-PEGylated rhG-CSF are 23.8 kD, 28.6kD and 33.8kD, respectively. Cell proliferation activity was detected by MTT assay using NFS-60 cell. The in vitro residual bioactivity of mono-, di- and tri-PEGylated rhG-CSF were 90%, 75% and 43% respectively, comparing with the un-conjugated rhG-CSF. These results indicated that the un-conjugated rhG-CSF and excess free PEG can be removed completely and the three conjugate species can be purified into homogeneity by the two consecutive ion-exchange chromatographic steps. The purification procedure is easy to scale-up, high in performance and recovery.

Chromatography, Ion Exchange↗
PubMed2003

Development of a root feeding system based on a fiber ion-exchange substrate for space plant growth chamber "Vitacycle".

Selecting a plant root nutrient delivery system is one of the key aspects of designing root modules for space plant growth chambers. This article examines a number of the nutrient delivery systems and shows the most suitable technique for providing nutrients to roots in microgravity, which to date are ion-exchange artificial soils. In addition, this article characterizes the ion composition and hydrophysical parameters of a new Russian artificial ion charged fiber substrate, BIONA-V3. The BIONA-V3 substrate is comprised of ion-exchange resin fibers. The experimental data concerning the effects of anionic and cationic components on plant biomass is presented. Preliminary experiments with BIONA-V3 showed that 1 kg of dry BIONA-V3 produces up to 2.4 kg (fresh mass) of cabbage leaf or 180 g of dry plant mass per 1 dm3 of the substrate. Therefore, the root zone volume can be as small as 120 cm3 per plant. Further optimizing the nutrient composition of the resin fibers can increase space plant growth chamber productivity.

Biomass↗
PubMed2005

Ion exchange with natural zeolites: an alternative for water softening?

Possibility of using natural zeolites for water softening was investigated. Quantitative data regarding separation of calcium from water at various levels of hardness through ion exchange with the ammonium selective natural zeolite clinoptilolite is reported. Capacity of the zeolite towards calcium removal in the presence of ammonium at low concentrations and calcium at higher concentrations, and breakthrough characteristics are presented. The results have revealed that removal of calcium, and hence hardness, through ion exchange with clinoptilolite under those circumstances is a promising alternative, with surface capacities reaching 11 mg calcium/g clinoptilolite.

Calcium↗