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PubMed2002

Synthesis of a new ion exchanger, zirconium vanadate, and its application to the separation of barium and cesium radionuclides at tracer levels.

A new inorganic ion exchanger, zirconium vanadate, has been synthesized and characterized. Elemental analysis suggests that the probable formula of the compound is ZrO2, V2O5, 2H2O. The exchanger is highly stable in thermal, radiation and chemical environments. Radiochemical separation schemes for the 134Cs and 133Ba pair and also for separating the short-lived daughter 137Ba from its parent 137Cs using this newly synthesized ion exchanger have been developed.

Journal Article↗
PubMed2006

Dynamics of ion exchange between self-assembled redox polyelectrolyte multilayer modified electrode and liquid electrolyte.

A probe beam deflection (PBD) study of ion exchange between an electroactive polymer poly(allylamine)-bipyridyl-pyridine osmium complex film and liquid electrolyte is reported. The PBD measurements were made simultaneously to chronoamperometric oxidation-reduction cycles, to be able to detect kinetic effects in the ion exchange. Layer-by-layer (LbL) self-assembled redox polyelectrolyte films with osmium bipyridyl complex covalently attached to poly(allylamine) (PAH-Os) and poly(styrene sulfonate) (PSS) have been built by alternate electrostatic adsorption from soluble polyelectrolytes. The ionic exchange during initial conditioning of the film ("break-in") undergoing oxidation-reduction cycles and recovery after equilibration in the reduced state have shown an exchange of anions and cations with time lag between them. The effect of the nature of cation on the ionic exchange has been investigated with dilute HCl, LiCl, NaCl, and CsCl electrolytes. The ratio of anion to cation exchanged at the film-electrolyte interface has a strong dependence on the nature of charge in the topmost layer, that is, when negatively charged PSS is the capping layer, a larger proportion of cation exchange is observed. This demonstrates that the electrical potential distribution at the redox polyelectrolyte multilayer (PEM)/electrolyte interface determines the ionic flux in response to charge injection in the film.

Journal Article↗
PubMed1994

Competitive adsorption of alpha-lactalbumin and bovine serum albumin to a sulfopropyl ion-exchange membrane.

Breakthrough curves were measured for pure solutions of alpha-lactalbumin (ALA) and bovine serum albumin (BSA) individually, and for a binary mixture of the proteins, using a sulfopropyl ion-exchange membrane. The breakthrough curves were qualitatively consistent with local-equilibrium theory predictions. Competitive adsorption caused displacement of bound BSA monomer by the more strongly binding BSA dimer, illustrating that even apparently single-protein systems may display multicomponent competitive behavior. In the two-protein experiment, ALA was competitively displaced by the more strongly binding BSA monomer and dimer, indicating that the binding strength was in the order: BSA dimer > BSA monomer > ALA.

Adsorption↗
PubMedDate not supplied

Effects of ion exchange on hardness and fracture toughness of dental ceramics.

Dental ceramics generally fail because of the growth of microscopic surface flaws that form during processing or finishing or that result from surface impact during service. The ion-exchange process has been shown to be effective in improving the flexural strength of most dental porcelains through the development of a compressive surface layer. The Vickers hardness and crack resistance of several commercial dental ceramics were determined by indentation techniques. The results of this investigation indicate that ion-exchange reinforcement can significantly improve the resistance of the ceramic surface to crack propagation with little effect on apparent surface hardness.

Analysis of Variance↗
PubMed1978

Ion exchange method for determining mephentermine sulfate in drug formulations: collaborative study.

Ion exchange chromatography is used to separate mephentermine sulfate from drug formulations. The drug is subsequently measured by ultraviolet spectrophotometry. Assays on 4 commercial samples of tablets and injectables gave recoveries from 97.6 to 104% of declared. A collaborative study involving 2 tablet and 2 liquid formulations gave mean recoveries ranging from 94.7 to 99.3% and coefficients of variation from 1.39 to 2.00%.

Chromatography, Ion Exchange↗
PubMed1993

[Development of polymers for high performance ion-exchange chromatography and their application to analysis of human serum albumin components].

The versatility of 4-vinylpyridinium (4VP-EG-Q) and quaternized dimethylaminomethylstyrene (PDAMS-Q) polymers synthesized by suspension copolymerization as column packings for high performance ion-exchange chromatography was described. The proposed polymer columns afforded resolution of human/bovine serum albumin components, such as mercaptalbumin and nonmercaptalbumin. It was suggested that the physicochemical structure on the external surface of the ion-exchangers was very important in the resolution. The characteristics of 4VP-EG-Q column were effectively applied to the investigation of the metal-albumin complexes, whereas a rapid analysis of mercaptalbumin in the human serum using the PDAMS-Q column was performed by isocratic elution.

Chromatography, Ion Exchange↗
PubMed2003

Synthesis and characterization of ion-exchangeable titanate nanotubes.

Titanate nanotubes were synthesized under hydrothermal conditions. The optimized synthesis (100-180 degrees C, longer than 48 h), thermal and hydrothermal stability, ion exchangeability and consequent magnetic and optical properties of the titanate nanotubes were systematically studied in this paper. First, nanotubes with monodisperse pore-size distribution were prepared. The formation mechanism of the titanate nanotubes was also studied. Second, the thermal and hydrothermal stability were characterized with X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR), and Raman spectroscopy. Results showed that sodium ions played a significant role in the stability of the frameworks. Third, the selective ion exchangeability was demonstrated with a series of ions. The ion substitution also enlarged the BET surface area of the titanate nanotubes to 240 m(2) x g(-1). Combination of these two features implied that these nanotubes might be functionalized by substitution of different transitional-metal ions and consequently used for selective catalysis. Magnetism, photoluminescence, and UV/Vis spectra of the substituted titanate nanotubes revealed that the magnetic and optical properties of the nanotubes were modifiable.

Journal Article↗
PubMed2005

Simultaneous removal of perchlorate and nitrate from drinking water using the ion exchange membrane bioreactor concept.

This work evaluates the feasibility of the ion exchange membrane bioreactor (IEMB) concept for the simultaneous removal of perchlorate and nitrate from drinking water, when nitrate is present in the ppm range and perchlorate in the ppb range. The IEMB concept combines Donnan dialysis and simultaneous biological degradation of both pollutants. Membrane transport studies showed that Donnan dialysis is suitable for obtaining water with concentrations of perchlorate and nitrate below the recommended levels. However, the pollutants were accumulated in a receiving stream, thus requiring additional treatment before disposal. On the other hand, the IEMB process operated with hydraulic retention times ranging from 1.4 to 8.3h in the water compartment, proved to remove effectively perchlorate and nitrate while preserving the water composition with respect to other ions, thus avoiding secondary contamination of the treated water. For a polluted water stream containing 100 ppb of ClO(4)(-) and 60 ppm of NO(3)(-), the concentrations of both ions in the treated stream were kept below the recommended levels of 4 ppb for ClO(4)(-) and 25 ppm for NO(3)(-). The IEMB system was operated under ethanol limitation, but even under these conditions, an increase of the perchlorate and nitrate concentrations in the treated water was not observed for up to 6 days.

Bioreactors↗
PubMed1975

Liquid ion exchangers in paper chromatography of steoidal glucosiduronic acids. Influence of different exchangers on the mobility in chloroform-formamide and correlation of chromatographic data.

A group of 25 steroidal glucosiduronic acids was chromatographed on paper chloroform-formamide in the presence of several different liquid ion exchangers. Chromatograms were run also in three Bush-type systems. RF values were converted into RM values and the data were correlated by use of a series of regression equations of the type RM(Y) = a-RM(X) + b, in which X designates a standard system to which each other system (Y) is compared. The ratio of the slope a to the correlation coefficient r (i.e., a/r) is a measure of the resolving power of system Y relative to the standard system; intercept b, in association with slope a, is an indication of the polarity of system Y relative to X. The correlation coefficient r and the standard error of estimate sy-x are indications of whether solvent systems Y and X have very similar or relatively different resolving properties for a group of solutes. The regression equations are useful for correlating chromatographic data obtained from a group of compounds in several solvent systems. Properties of the chromatography systems are discussed and the relative importance of ion exchange and hydrogen bonding with the various solvent systems is pointed out. Delta RMg and delta RMr values are given for functional groups at several locations in the conjugates for ten of the chromatography systems.

Chloroform↗
PubMed2004

Comparative analysis of enzymatically digested kappa-carrageenans, using liquid chromatography on ion-exchange and porous graphitic carbon columns coupled to an evaporative light scattering detector.

Enzymatically digested kappa (A-G4S)-carrageenans, apart from their biological activities in plants, could be used as 'model' molecules to elucidate potential problems in nuclear magnetic resonance spectroscopy of carrageenans. Thus, oligosaccharides obtained from kappa-carrageenan by enzymatic digestion using kappa-carrageenase have been separated on silica and polymeric based ion-exchange and porous graphitic carbon (PGC) columns, coupled to an evaporative light scattering detector. Oligomers were separated on ion-exchange columns using a gradient of ammonium acetate as a developing ion, while analysis on PGC column presented an additional adjacent peak next to each main one, using a gradient of ammonium acetate in water/acetonitrile as a mobile phase. The phenomenon can be attributed to different retention mechanisms that govern the PGC surface. Furthermore, it has been demonstrated that acetonitrile can regulate the selectivity between the peaks raising hopes for preparative chromatography.

Carrageenan↗
PubMed1994

[Simultaneous determination of serum copper and zinc levels in patients with cancer of the digestive tract by ion-exchange chromatography].

Serum copper and zinc were simultaneously determined by ion-exchange chromatography (IC) in 35 normal volunteers and 45 patients with benign diseases or different stage cancers of the digestive tract. No significant differences of serum Cu, Zn and Cu/Zn ratio were found among normal volunteers, patients with benign diseases and those with stage I or II cancers, while in the group of stage III and IV cancer patients, serum Cu (26.53 +/- 1.41 mumol/L) and Cu/Zn ratio (2.25 +/- 0.16) were very significantly elevated (P < 0.01) and that of serum Zn (11.78 +/- 0.46 mumol/L) was remarkably decreased (P < 0.05). Our results showed that serum Cu, Zn and Cu/Zn ratio were of no help in detecting early stage cancers and in differentiating them from benign diseases but were useful in predicting stages of cancers before operation for a better choice of therapy.

Adult↗
PubMed1984

Haemoglobinopathies: a pitfall in the assessment of glycosylated haemoglobin by ion-exchange chromatography.

Total glycosylated haemoglobin was determined by a minicolumn ion-exchange chromatography technique (Bio-Rad) and correlated with the mean of fasting and post-prandial blood glucose values for the preceding 6 weeks. In 360 diabetic subjects, free of congenital haemoglobinopathies and other detected causes of haemoglobin A1 misinterpretation (reference diabetic group), a highly significant correlation was established between haemoglobin A1 and glucose (y = 0.54 X +4.91; r = 0.791; p less than 0.01). In 28 of the 29 patients with heterozygous haemoglobinopathies (HbS, C, D, E), the apparent haemoglobin A1 values were lower than expected according to the 95% confidence limits of the diabetic reference group. The apparent haemoglobin A1 value was above these limits in patient 29, with beta thalassaemia. Patients with inappropriate glycosylated haemoglobin values should be investigated for causes of haemoglobin A1 misinterpretation, in particular, haemoglobinopathies.

Blood Glucose↗