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PubMed1984

Separation of trace amounts of Ca2+ and Sr2+ from K+ and Rb+ with a hydrous manganese dioxide ion exchanger.

Extremely large separation factors (greater than 10(2)) were found for Na-Mg, K-Ca and Rb-Sr metal ion pairs on a cryptomelane-type hydrous manganese dioxide (CRYMO) ion exchanger. Ca2+ and Sr2+ ions were quantitatively separated from a thousand times of K+ and Rb+ ions on mole basis, respectively, by using the CRYMO column. The hopeful utilities of the CRYMO are suggested for the radiochemical ion-exchange separation of radiomagnesium and radiostrontium from K and Rb salt targets.

Calcium↗
PubMed1973

Model hydrophobic ion exchange membrane.

Two models of hydrophobic ion exchange membranes were examined theoretically with regard to the characteristics of cellulose acetate-nitrate membranes saturated with hydrophobic solvents. The first model, consisting of fixed negative sites dispersed in a homogeneous medium of low dielectric constant, was shown to be invalid for the experimental membranes. The second model, consisting of fixed negative sites in an aqueous channel surrounded by a medium of low dielectric constant, explains many properties of the cellulose acetate-nitrate hydrophobic membranes and was analyzed in some detail. Organic cations can enter the membranes through the hydrophobic phase as well as through the aqueous channels. The mechanism of counterion movement in such a model is assumed to consist of exchange of vacancies and or double-occupied sites positions. The presence of the medium of low dielectric constant around the aqueous channel increases the "self"-energy of the ions in the channel and the electrostatic interaction between a fixed site and a counterion in the membrane. Both these factors can account for the marked dependence of ion mobility in the aqueous channels on the dielectric constant of the surrounding medium. The model predicts membrane preference for monovalent counterions over divalent ones.

Capillary Action↗
PubMed2003

Suppression of subcritical crack growth in a leucite-reinforced dental glass by ion exchange.

Glass-ceramic materials are frequently used in prosthetic dentistry because of their excellent esthetics. Problematic aspects of glass ceramics are their limited strength, the scatter in their strength data, and their time-dependent strength decrease due to subcritical crack growth effects. The short-term strength level can be significantly increased by an ion-exchange process in a potassium salt. A dual ion-exchange process in KNO3/NaNO3 can additionally improve the scatter-in-strength. The objective of the present study was to examine the effect of a single and a dual ion-exchange process on the characteristic time-dependent strength decrease of a leucite-reinforced dental glass. The parameters of subcritical crack growth were evaluated by using the constant stress rate flexural strength test. Both ion-exchange processes showed a pronounced effect on the subcritical crack growth of the glass-ceramic material. The exponential crack parameter n was increased from 25 to 52 by the single-exchange and to 107 by the dual-exchange process, respectively. We conclude that the time-dependent strength decrease of a dental glass-ceramic material can be significantly limited by the ion-exchange process. This could improve the clinical reliability of dental restorations made from this class of materials.

Aluminum Silicates↗
PubMed1969

Ion exchange properties of the canine carotid artery.

Properties of the ion exchange mechanisms in the arterial wall were investigated by comparing water and electrolyte contents, and by measuring the steady-state entry of (22)Na, (42)K, and (26)Cl under similar in vitro conditions. Overnight incubation of freshly dissected slices at 2 degrees C resulted in an accumulation of sodium, chloride, and water and a loss of potassium. Subsequent incubation at 37 degrees C in a physiological solution resulted in a reversal of these processes. Loss of water, sodium, and chloride at 37 degrees C could also take place into a potassium-free solution. Under all conditions studied the quantity of fast exchanging electrolyte (half time less than 3 min) exceeded that contained in the inulin and sucrose spaces. The excess could not be attributed to connective tissue adsorption. A kinetic model was applied to the flux data which incorporated two simultaneous processes: bulk diffusion and a reversible reaction. The assumption that the cell membrane behaved as a discrete barrier for the exchange of all cell electrolyte was relaxed in this approach. A theory based upon the physicochemical properties of proteins, ions, and water in biological systems provided a physical basis for the kinetic model, and for interpreting the ion exchange properties of the vascular wall.

Animals↗
PubMed1986

Isolation of heavy chain isoenzymes of myosin subfragment 1 by high performance ion exchange chromatography.

The procedure of high performance ion-exchange chromatography has been used to fractionate subfragment 1 of myosin (SF1) into its isoenzymic forms. In contrast to conventional ion-exchange procedures which yield two fractions corresponding to SF1(A1) and SF1(A2), the high performance liquid chromatography (HPLC) procedure resolves SF1 into four discrete fractions. The first pair that is eluted appears to be A1-containing isoenzymes while the latter pair corresponds to the A2 forms based on their polypeptide compositions by gel electrophoresis in the presence of sodium dodecyl sulfate. By gel electrophoresis under nondenaturing conditions it is not possible to differentiate between the two fractions corresponding to each isoenzyme. Although very minor differences between the fractions can be seen by the presence of extraneous peptides, these are present in far below stoichiometric amounts and, therefore, make it very unlikely that the superior fractionation by the HPLC procedure is based on their presence. An examination of the heavy chain heterogeneity in each of these fractions by peptide mapping revealed that the extra separation was based on this factor. Thus the HPLC procedure is capable of providing separation of SF1 into heavy chain-based isozymes as well as the light chain forms. ATPase measurements of these fractions reveal only minor differences in the Ca2+- and EDTA-activated ATPase.

Adenosine Triphosphatases↗
PubMed2000

Zirconium and hafnium hydrogen monothiophosphates, H2Zr(PO3S)2 and H2Hf(PO3S)2. Syntheses and selective ion-exchange properties of sulfur-containing analogues of H2M(PO4)2 (M = Zr, Hf).

The reactions between aqueous solutions of M4+ (M = Zr, Hf) and PO3S3- each result in the precipitation of a white gel that can be dried to a powder. Elemental analysis results for the white polycrystalline product yield a stoichiometry of H2M(PO3S)2. These new compounds are characterized by thermal analysis (DSC, TG-MS), vibrational spectroscopy (FT-IR, FT-Raman), 31P MAS NMR spectroscopy, energy-dispersive spectroscopy (EDS), and powder X-ray diffraction (XRD). On the basis of the characterizations and the results of trialkylamine intercalation experiments, we conclude that the H2M(PO3S)2 compounds have a layered structure that is likely similar to that of alpha-H2Zr(PO4)2.H2O. The interlayer spacing for both H2M(PO3S)2 compounds, determined by XRD, is approximately 9.4 A. Our characterization results suggest that the sulfur atom of each PO3S3- group is preferentially pointed into the interlayer region of the compound and is protonated. Two of the many potentially interesting properties of H2Zr(PO3S)2, its ion-exchange capacity and selectivity, are investigated. H2Zr(PO3S)2 is demonstrated to be an effective and recyclable ion-exchange material for both Zn2+(aq) and Cd2+(aq). Mass balance experiments indicate that the removal of Cd2+(aq) and Zn2+(aq) ions by solid H2Zr(PO3S)2 occurs by an ion-exchange process. Ion exchange results in the formation of the new compounds H0.2Cd0.9Zr(PO3S)2 and H0.50Zn0.75Zr(PO3S)2. The extraction of metal ions is monitored by XRD, vibrational spectroscopy, and elemental analysis. H2Zr(PO3S)2 reversibly intercalates Zn2+(aq) ions through three complete cycles of intercalation and deintercalation without any loss of ion-exchange capacity.

Journal Article↗
PubMed1983

Effects of whole blood storage on results for glycosylated hemoglobin as measured by ion-exchange chromatography, affinity chromatography, and colorimetry.

After storage of whole blood at either 4 or 20 degrees C, results for glycosylated hemoglobin by ion-exchange chromatography ("high-performance" liquid and mini-column chromatography), thiobarbituric acid colorimetry, and affinity chromatography were compared. At 4 degrees C, all methods gave acceptable results for samples stored for as long as a week. At 20 degrees C, the colorimetric and affinity methods also showed sample stability for a week or more. The ion-exchange methods were associated with a marked increase in values for glycosylated hemoglobin after a few days of storage. Evidently, care in details of sample collection and handling is especially important for ion-exchange methods, and the colorimetric and affinity methods have advantages over ion exchange in situations where long delays between sample collection and assay are unavoidable.

Blood Preservation↗
PubMed1978

Binding of drugs to ion-exchange resins in simulated gastric fluid.

The binding of 13 frequently abused drugs to two ion-exchange resins was studied in simulated gastric fluid. The results were compared with those previously obtained with activated charcoal as the adsorbent. The ion-exchange resins adsorbed the drugs more slowly than activated charcoal, and the binding capacities of the resins were inferior. These ion-exchange resins are unlikely to be very useful in removing drugs from the stomach.

Adsorption↗
PubMedDate not supplied

Analysis in the ion exchange tradition.

Amino acid analysis by ion exchange chromatography is just as important an analytical tool in 1986 as it was in the late 1950s, when Moore and Stein first described an automated AAA instrument.

Amino Acids↗
PubMed1994

Synthesis and characterization of silica-based aliphatic ion exchangers.

The chemical literature describing preparation of aliphatic ion exchangers is limited, and although such phases are available commercially, the synthetic schemes are proprietary. The course of our research required the preparation of silica-based aliphatic cation and anion exchangers for which the desired base silica and/or ligand properties were not commercially available. We developed synthetic schemes to prepare silica-based aliphatic sulfonic acid, carboxylic acid and quaternary ammonium ion-exchange phases with active exchange capacities of 0.2-0.9 mumol/m2. Multiple techniques were used to characterize the intermediate and final phases produced in the syntheses, including Fourier transform diffuse reflectance infrared spectroscopy, spot tests, elemental analysis, acid-base titration and elution analysis.

Anion Exchange Resins↗
PubMed2003

Titanium(IV) tungstosilicate and titanium(IV) tungstophosphate: two new inorganic ion exchangers.

Crystalline phases of Ti(IV) tungstosilicate and Ti(IV) tungstophosphate have been synthesised. The ion-exchange capacities of Ti(IV) tungstosilicate and Ti(IV) tungstophosphate have been reported as 0.44 and 0.80 mequiv./g, respectively. Both materials show monofunctional ion-exchange characteristic and are stable in 0.1 M solutions of HNO3, HCl, H2SO4 and acetone and benzene. Ti(IV) tungstosilicate is found to be more stable thermally than Ti(IV) tungstophosphate (loss in ion-exchange capacity was found as 58 and 80%, respectively for samples heated at 200 degrees C). The Kd values for heavy metals such as Pb, Hg, Cd, Sb, Co, Zn, Ni, Fe, Cr etc. have been reported in demineralised water and two surfactant media by batch processes. Cr3+, Fe3+ and Sn4+ are totally adsorbed on both the materials in demineralised water while a decrease in Kd value with increase in concentration of two surfactants is reported. On the basis of Kd values for metal ions, thirteen binary separations and five ternary separations on Ti(IV) tungstosilicate and thirteen different binary separations and four different ternary separations on Ti(IV) tungstophosphate have been achieved. Separation of methylamine from ethylamine has been done by GC on a column packed with Ti(IV) tungstophosphate.

Ion Exchange Resins↗
PubMed2006

Ion-exchange and potentiometric characterization of Al-cystine and Al-cysteine complexes.

The interaction between aluminium and cysteine and cystine was evaluated by means of ion-exchange experiments and potentiometry. Ion-exchange experiments included other ligands with affinity for aluminium and two kinds of resins, either a Na+ -form or an Al3+ -form exchanger. The ability of the ligands to keep aluminium in solution in the presence of the Na+ exchanger or to withdraw it from the Al3+ -form resin was evaluated. Aluminium quantification was carried out by either graphite-furnace or flame atomic absorption spectrometry. Aluminium extraction isotherms were linearised using the Scatchard plot, and stability constants were obtained from the curves' slopes. The experiments showed that the ability of the ligands to withdraw aluminium from the Al3+ -form resin increased following the order cysteine < oxalate < citrate = cystine < nitrilotriacetic acid < ethylenediaminetetraacetic acid. Potentiometric titrations, carried out in aqueous solution with constant ionic strength and temperature, showed that the predominant species in solution have a metal-ligand proportion of 1:1 for both amino acids. The main species are Al(OH)3L, with log K of 6.2 for cysteine, and AlL and Al(OH)L, with log K of 10.3 and 1.7, respectively, for cystine. Stability constants obtained from the Scatchard plots showed a linear correlation with the stability constants obtained by potentiometry for cystine and cysteine in this work and those collected from the literature for the other ligands. These results show that cysteine and cystine extract and maintain aluminium in solution, which may explain elevated concentrations of aluminium in parenteral nutrition solutions containing these amino acids.

Aluminum↗
PubMed2004

Cation mobility and kinetics of ion exchange in zirconium hydrogen monothiophosphate hydrate, Zr(HPO(3)S)(2)x1.5H(2)O.

The ion conductivity of zirconium hydrogen monothiophosphate (Zr(HPO(3)S)(2)x1.5H(2)O) has been measured by impedance spectroscopy. The measured value of proton conductivity is 3 x 10(-5) S/cm at 298 K. Conductivity was shown to decrease with increasing temperature due to a dehydration process. Above 450 K, the conductivity is likely governed by proton transport in the anhydrous phase Zr(HPO(3)S)(2). The activation energies of proton conductivity were measured to be 18 +/- 2 kJ/mol for Zr(HPO(3)S)(2)x1.5H(2)O and 60 +/- 3 kJ/mol for the anhydrous compound. The kinetics of ion exchange was studied with the use of potentiometric titration for several ion pairs, H(+)/Na(+), H(+)/Zn(2+), and Na(+)/Zn(2+) in Zr(HPO(3)S)(2)x1.5H(2)O. The diffusion coefficient values for H(+)/Na(+) ion exchange in Zr(HPO(3)S)(2)x1.5H(2)O are lower than those reported in alpha-zirconium phosphate. At the same time, the mobility of zinc ions in Zr(HPO(3)S)(2)x1.5H(2)O is higher than sodium ion mobility. The ion exchange H(+)/Zn(2+) is accompanied by the slow hydrolysis of the initial compound. In all cases, the powdered solids were evaluated by powder X-ray diffraction, and particle sizes were controlled by grinding and sieving the powders.

Journal Article↗
PubMed1987

Combination of Zetaprep mass ion-exchange media and high-performance cation-exchange chromatography for the purification of high-purity monoclonal antibodies.

A procedure involving diafiltration, mass ion exchange on a QAE Zetaprep disk, gel chromatography and cation-exchange chromatography was used for the purification of mouse monoclonal antibodies from hybridoma culture supernatant. Prior to the separation steps, the starting solution was adjusted to the desired pH and conductivity. Diafiltration was used for this purpose in order to keep the volume constant or even to reduce the volume of sample. A QAE Zetaprep disk was used to remove the main protein contaminants from the culture supernatant. After washing unbound proteins out of the Zetaprep disk, slightly bound protein was eluted with a buffer solution containing 50 mM sodium chloride. The monoclonal antibody was eluted with a solution containing 150 mM sodium chloride. The purity of the eluted antibody was 50%, and was increased to 99% by subsequent high-performance cat-ion-exchange chromatography. The purity was determined by means of sodium-dodecyl sulphate polyacrylamide gel electrophoresis and silver staining. The advantage of the two high-performance techniques, mass ion exchange and high-performance cation-exchange chromatography, are the high-flow-rates and the high resolution that can be obtained. These techniques are suitable for the production of injectable therapeutic preparations.

Animals↗
PubMedDate not supplied

The ion exchange properties of human post-mortem caecal and colonic mucus: the effect of sodium butyrate.

This study examined Na+/H+ ion exchange of caecal and colonic mucus. Two distinct Na+/H+ ion exchange populations of caecal mucus were identified, one group being a cation exchanger and the other an anion exchanger, suggesting that caecal mucus has ampholyte properties responsive to changing physical and chemical properties of luminal contents. Mucus from the colon was consistently an anionic exchanger--this may aid water and electrolyte absorption in the colon. When mucus was incubated with sodium butyrate, the Na+/H+ ion exchange properties of the mucus were decreased.

Adolescent↗
PubMed2003

Analysis and critical comparison of the reversed-phase and ion-exchange contributions to retention on polybutadiene coated zirconia and octadecyl silane bonded silica phases.

The two major modes of retention of basic compounds in reversed-phase liquid chromatography on both octadecyl silane bonded silica-based (ODS) and polybutadiene coated zirconia (PBD-ZrO2) materials are hydrophobic and ion-exchange (Coulombic) interactions. Although the influence of reversed-phase and Coulombic interactions on the chromatography of organic cations is qualitatively well recognized, the quantitative relationship between hydrophobic and ion-exchange interactions remains unclear. In this work, the retention mechanisms on both of the above types of phases were probed by studying the retention of a homologous series of p-alkylbenzylamines as a function of the ammonium concentration in the eluent. The various columns tested were studied in terms of plots of retention factor vs. the inverse of the displacingcation concentration. The analysis of such plots as well as plots of log k' vs. number of methylene groups in the solutes and plots of log k' vs. log[NH4+] clearly shows that at least two types of sites--a pure reversed-phase site and a "hydrophobically-assisted ion-exchange site" similar to the type of site described by Neue [J. Chromatogr. A 925 (2001) 49] are needed to explain the observations. In addition, we have found a quantitative measure of the relative amount of reversed-phase and ion-exchange interaction on a given solute has on a given stationary phase which allows unambiguous classification of columns. It is now clear that ion-exchange contributions to retention on PBD-ZrO2, sometimes exceeding 90%, are even more important than previously thought and relative to hydrophobic interaction much more significant on PBD-ZrO2 than on ODS type-B silicas.

Buffers↗
PubMed2006

High-capacity purification of hen egg-white proteins by ion-exchange electrochromatography with an oscillatory transverse electric field.

The ion-exchange electrochromatography with an oscillatory electric field perpendicular to the mobile-phase flow driven by pressure (pIEEC) was used to separate hen egg-white (HEW) proteins. The results were compared with those of normal ion-exchange chromatography (IEC). The column was designed as three-compartment rectangular column of 2-mL with dimensions (length x width x depth) of 40 x 10 x 5 mm(3) and the electric field was applied across the direction of column width. Q Sepharose FF was packed into the central compartment as the chromatographic bed. It was confirmed that the dynamic binding capacity (DBC) of different proteins (ovotransferrin and ovalbumin) in the HEW solution increased 2.3 times when an oscillatory electric current of 30 mA at 1/20 Hz was applied in the transverse column direction. Then, the HEW proteins were separated by the pIEEC at loading amounts 2.3-fold higher than those by the IEC. When the feedstock of about one-third of the DBC was applied to the columns (i.e., 7 mL for the pIEEC and 3 mL for the IEC), similar separation efficiencies of the two chromatographic modes were achieved. Both the recovery yield and purity reached 73% to over 90%. The results indicate that the pIEEC is promising for high-capacity purification of proteins.

Animals↗