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PubMed2005

Local structures of ions at ion-exchange resin/solution interface.

The local structures of Cl- and Br- in anion-exchange resins have been studied by X-ray absorption fine structure (XAFS), and separation selectivity is discussed on the basis of results. When two different anion-exchange resins having trimethylammonium and dimethylammonium groups as anion-exchange groups are employed for ion-exchange experiments, slightly higher Br- selectivity has been obtained with the former. XAFS has indicated that the average hydration numbers for a given anion is not affected by the structure of the ion-exchange group, but that the extent of ion-association between the anion and the ion-exchange groups depends on the type of the ion-exchange group. Shorter interaction distance (and in turn stronger ion-association) has been confirmed for the dimethylammonium-type resin, and is consistent with lower Br- selectivity of this resin.

Anion Exchange Resins↗
PubMed2002

Use of hop (Humulus lupulus) agricultural by-products for the reduction of aqueous lead(II) environmental health hazards.

The agricultural by-products of the hop plant (Humulus lupulus L.) were investigated to determine their potential for use in the removal of heavy lead(II) ions from contaminated aqueous solutions. Separate batch laboratory experiments were performed to establish the optimal binding pH, time exposures, and capacity of the metal adsorption for lead(II) ions by dried and ground hop leaves and stems biomass. Results from these studies have shown a pH dependent binding trend from pH 2-6, with optimum binding occurring around pH 5.0. Time dependency experiments showed a rapid adsorption of lead(II) ions within the first 5 min of contact. Binding capacity experiments demonstrated that 74.2mg of lead(II) were bound per gram of leaf biomass. Similarly overall capacity was seen for the leaves and stems. Desorption of 99% of the bound lead(II) ions was achieved by exposing the metal laden biomass to 0.5M sodium citrate. Further experiments were performed with silica-immobilized hop tissues to determine the lead(II) binding ability under flow conditions. Comparison studies were performed with ion-exchange resins to evaluate the binding ability and to gain further insight into the metal binding mechanism. X-ray absorption spectroscopy experiments were also utilized to gain further insight into the possible lead(II) binding mechanism by the hop plant tissue. Results from these studies indicate that carboxyl ligands are involved in the binding of lead(II) from aqueous solution. These findings show that the use of hop agricultural waste products may be a viable alternative, for the removal and recovery of aqueous lead(II) ions from contaminated waters.

Adsorption↗
PubMed1979

[Hemoperfusion through adsorbents as a method of preoperative preparation of patients with severe form of mechanical jaundice].

The method of haemoperfusion through the ion exchange resin and active carbon was used 15 times in 13 patients with heavy forms of mechanical subhepatogenous jaundice. The haemoperfusion was used as a method of preoperative preparation for reduction of hyperbilirubinemia and cholemic intoxication and for prevention of possible postoperative complications. One patient recovered. One patient died of progressing hepatic insufficiency. The rest of the patients were subjected to surgical interventions for the main disease.

Charcoal↗
PubMed2007

Development of a new approach for microbial decontamination of water using modified Fenton's reaction.

Microbial decontamination of water was carried out using a novel radical generating system consisting of ion exchange resin, copper and hydrogen peroxide. The system was successful in reducing the microbial load in water by more than 99% in 15 min and is effective against all the microorganisms tested. The method was also successful in decontaminating the flood water obtained from Industrial Canal and 17th Street Canal in New Orleans. Decontamination is due to the formation of hydroxyl radicals, formed during the decomposition of hydrogen peroxide by the metal-polymer complex.

Copper↗
PubMed2006

New polymer-supported ion-complexing agents: design, preparation and metal ion affinities of immobilized ligands.

Polymer-supported reagents are comprised of crosslinked polymer networks that have been modified with ligands capable of selective metal ion complexation. Applications of these polymers are in environmental remediation, ion chromatography, sensor technology, and hydrometallurgy. Bifunctional polymers with diphosphonate/sulfonate ligands have a high selectivity for actinide ions. The distribution coefficient for the uranyl ion from 1 M nitric acid is 70,000, compared to 900 for the monophosphonate/sulfonate polymer and 200 for the sulfonic acid ion-exchange resin. A bifunctional trihexyl/triethylammonium polymer has a high affinity and selectivity for pertechnetate and perchlorate anions from groundwater. In one example, its distribution coefficient for perchlorate ions in the presence of competing anions is 3,300,000, compared to 203,180 for a commercially available anion-exchange resin. Polystyrene modified with N-methyl-D-glucamine ligands is capable of selectively complexing arsenate from groundwater. It complexes 99% of the arsenate present in a solution of 100 mg/L arsenate with 560 mg/L sulfate ions. Its selectivity is retained even in the presence of 400 mg/L phosphate. There is no affinity for arsenate above pH 9, allowing for the polymer to be regenerated with moderate alkali solution. In studies aimed at developing a Hg(II)-selective resin, simple amine resins were found to have a high Hg(II) affinity and that affinity is dependent upon the solution pH and the counterion.

Arsenic↗
PubMed2002

Preparation of phytate-removed deamidated soybean globulins by ion exchangers and characterization of their calcium-binding ability.

Phytate-removed deamidated soybean globulins were prepared using ion-exchange resins to provide them with a functional property to enhance calcium absorption in the body. The phosphorus level was reduced from 45 to 20 micromol/g using 0.05 g/mL of AE-4, an anion-exchange resin with a (2-hydroxyethyl)dimethylammonium group, in 0.2% soybean globulin solution for 1 h at 4 degrees C, and 90-92% of the phosphorus in defatted soybeans could be removed. As for deamidation, CE-4, a cation-exchange resin of the carboxylate type, showed a much higher deamidation activity than CE-1 and CE-2, cation-exchange resins of the sulfonate type. No peptide bond hydrolysis was observed for any cation-exchange resin treated at 4 degrees C. There was no significant difference in the amount of acid amide deamidated at temperatures between 4 and 50 degrees C. The deamidation level was able to increase to 73% using 0.10 g/mL of CE-4 in a 0.2% soybean globulin solution for 6 h at 4 degrees C. The amount of calcium bound to the soybean globulins decreased with removal of the phytate but increased with deamidation.

Biological Availability↗
PubMedDate not supplied

[Progresses in the preparation of protein hydrolysates for the treatment of diseases related to aminoacid metabolism disorders (author's transl)].

A method is described for the preparation of a protein hydrolysate to be used in diets for the treatment of the diseases primarily related to disorder of amino acid Metabolism. The method is based on the use of ion-exchange resins to avoid the use of mineral acids so that the time of hydrolysis is reduced to 7 hrs and aminoacids destroyed in the usual industrial preparations are protected. Yields of 70% are obtained with an hydrolysis ratio of 90%. These results allow the preparation of hydrolysates with a high chemical score in which the aminoacid responsible for the diseases primarily related to disorder of amino acid Metabolism symtoms have been removed.

Amino Acid Metabolism, Inborn Errors↗
PubMedDate not supplied

Copper and zinc speciation in the solution of a soil-sludge mixture.

Only a small fraction of the transition metals content in sludge-amended soils is soluble, and yet this fraction is a major contributor to the mobility and bioavailability of the metals. The chemical species of zinc (Zn) and copper (Cu) in the soluble fractions of soil-sludge mixtures were characterized with respect to their charge, molecular weight, and stoichiometry using ion exchange resin and gel chromatography procedures. The change in the metals' species with time after sludge application was followed for 100 d. Copper in the water extracts of the sludge-sand mixtures was found almost exclusively in low molecular weight (below 1000 Da) complexes. Higher molecular weight (around 2500 Da) dissolved organic carbon (DOC) was present in the extracts as well, but this DOC fraction exhibited little complexation. Copper was present in the extracts mainly as negatively charged species throughout the incubation period, and zinc tended to form zwitter ions. As incubation progressed, the relative content of positively charged Zn in solution increased. Complexation capacity of DOC in sludge water extract, extrapolated to infinite dilution, was 8.75 mM Ca g(-1) DOC. When the complexation capacity of the extract is near saturation, a mean Cu-DOC complex can be defined. It consists of 1.9 Cu atoms attached to DOC species containing 5.6 C atoms. Thus, the organic Cu complexes consist primarily of about two Cu ions attached to DOC species containing only five or six C atoms. Amino acids and small peptides or polycarboxylic acids, such as citric acid, thus may be important complexing agents of the metal.

Amino Acids↗
PubMed1999

Separation of carboxylic acids on a weakly acidic cation-exchange resin by ion-exclusion chromatography.

The separation of various carboxylic acids was performed on a polymethacrylate-based weakly acidic cation-exchange resin (TSKgel OApak-A) using ion-exclusion chromatography under the acidic elution conditions. When a diluted sulfuric acid solution was used as the eluent, highly sensitive conductimetric detection of carboxylic acids was achieved without increasing the background conductance of the eluent. This method was more sensitive than using benzoic acid eluent and enabled a good resolution of dicarboxylic as well as monocarboxylic acids. The addition of 5-20% methanol to the eluent considerably reduced the retention times of carboxylic acids with hydrophobic nature.

Carboxylic Acids↗
PubMed2004

Highly sensitive determination of hydrazine ion by ion-exclusion chromatography with ion-exchange enhancement of conductivity detection.

An ion-exclusion chromatography method with ion-exchange enhancement of conductivity was developed for the selective separation and sensitive determination of hydrazine ion from alkali/alkaline earth metal cations and ammonium ion. Hydrazine ion was separated by ion-exclusion/penetration effect from other cations on a weakly basic anion-exchange column in the OH- form (TSKgel DEAE-5PW). Moreover, two different ion-exchange resin columns were inserted between the separating column and conductimetric detector in order to improve the sensitivity of hydrazine ion. The first enhancement column packed with a strongly basic anion-exchange resin in the SO4(2-) form (TSKgel SAX) for hydrazine ion can convert from N2H5OH to (N2H5)2SO4. Moreover, the second enhancement column packed with a strongly acidic cation-change resin in the H+ form (TSKgel SCX) can convert to H2SO4. As a result, the sensitivity of hydrazine ion using two conductivity enhancement columns could be 26.8-times greater than using the separating column alone. This method was effectiveness also for the enhancement of ammonium ion (6.1-times) and sodium ion (1.2-times). The calibration graph of hydrazine ion detected as H2SO4 was linear over the concentration range of 0.001-100 ppm (r2 = 0.9988). The detection limit of hydrazine ion in this system was 0.64 ppb. Therefore, hydrazine ion in real boiler water sample could be accurately determined, avoiding the interference of other cations.

Calibration↗
PubMed1974

Detection of staphylococcal enterotoxin in foods.

A short procedure for the extraction of staphylococcal enterotoxins from food materials has been developed. The procedure involves extraction of the food at pH 4.5, centrifugation, extraction of the supernatant with CHCl(3) (pH 7.5), extraction of the enterotoxin from the water layer with CG-50 ion exchange resin (pH 5.4 to 5.9), and treatment of the eluate with agar and concentration with Carbowax 20-M. The concentrate was extracted with CHCl(3), and the water layer was lyophilized. The dried material was dissolved in a 1% trypsin solution and placed on microslides, which were incubated 24 h at 37 C. The time required for enterotoxin analysis was 3 days with microslides and 1 day with the reversed passive hemagglutination technique.

Chemical Precipitation↗
PubMed2006

Remaining acetamide in acetonitrile degradation using nitrile hydratase- and amidase-producing microorganisms.

The tandem conversion process involving nitrile hydratase- and amidase-producing microorganisms has potential for use in the treatment of acetonitrile-containing wastes. In that process, the acetamide hydrolysis step catalyzed by amidase is very slow compared with the acetonitrile hydration step catalyzed by nitrile hydratase, and a small amount of acetamide remains in the resulting solution. This study aimed to improve the efficiency of the acetamide hydrolysis step. An amidase-producing microorganism, Rhodococcus sp. S13-4, was newly obtained, whose use enabled rapid acetamide degradation. Though residual acetamide was still detected, it was successfully reduced by the addition of cation/anion mixed ion exchange resin or calcium hydroxide after the acetamide hydrolysis reaction using Rhodococcus sp. S13-4 cells. This result implies that acetamide hydrolysis and acetamide formation are in equilibrium. The incubation of Rhodococcus sp. S13-4 cells with high concentrations of ammonium acetate produced acetamide. The purified amidase from Rhodococcus sp. S13-4 revealed the acetamide formation activity (specific activity of 30.6 U/mg protein). This suggests that the amidase-catalyzed amide formation may cause the remaining of acetamide in the acetonitrile conversion process.

Acetamides↗
PubMed2000

Adsorption of inulinases in ion-exchange columns.

The use of adsorption columns packed with ion-exchange resins for recovering, concentrating and purifying proteins is now widespread. The present work consists of a study on the dynamic behavior of adsorption columns that uses two kinds of adsorbents: a cationic and an anionic resin. A frontal analysis of the columns was performed with experimental data obtained from Fructozyme, a mixture of inulinase enzymes. The parameters of a Langmuir type of isotherm and adsorption kinetics were obtained from experimental tests in a batch system. A numerical technique based on orthogonal collocation and a fourth-order Runge-Kutta method was coupled with a nonlinear optimization method to predict the coefficients of the rate equations, which are fundamental for scale-up purposes.

Adsorption↗
PubMed1984

Recovery of plant amines with carboxylic ion-exchange substrates and their subsequent analysis by thin-layer chromatography.

Two grades of carboxymethylcellulose (CMC) and five ion-exchange resins were compared for their effectiveness in recovering endogenous amines from plant extracts. If amine loss was to be limited to 10%, the H+ and Na+ forms of CMC could not be loaded with the solutes from more than 0.25 and 1.5 gram fresh weight (gfw) tissue per ml bed volume respectively. The corresponding ionic forms of a typical resin, Amberlite CG-50, would tolerate loadings ca. 5 X higher than this. However, it was then necessary to use very slow flow-rates (13 ml cm-2 h-1) for both applying and eluting the amines and, even so, they could not be quantitatively displaced from any resin tested, with the possible exception of Duolite C433. If the extract was acidic, maximum permissible loadings were reduced by a factor of 3 to 20, depending on substrate and ionic form. The composition of the amine fraction was essentially the same whatever substrate was used for its recovery and whatever percentage of it had been lost.

Amines↗
PubMed1991

Studies of the development of optical fiber sensors for biochemical analysis.

An optical fiber sensor utilizing Thymol blue and an ion-exchange resin complex in a cellulose acetate membrane was developed. By monitoring several different chromophores of Thymol blue, the sensor could measure the pH of the solution from 1.0 to 12.0 with good reproducibility. An optical fiber glucose sensor utilizing a cellulose acetate membrane containing glucose oxidase, 2,7-diaminofluorene dihydrochloride, and sodium N-(3-sulfopropyl)-3,3',5,5'-tetramethylbenzidine was developed. Reflectance changes at 580 nm were large enough to trace changes in glucose concentration in physiological saline solution.

Biosensing Techniques↗
PubMed1995

High-performance liquid chromatography of amino acids, peptides and proteins. CXXXVIII. Adsorption of horse heart cytochrome c onto a tentacle-type cation exchanger.

Determination of the change in the Gibb's free energy from the adsorption isotherm associated with the interaction between a biomolecule and an ion-exchange resin is often achieved by assuming that a Langmuirean model prevails. However, the adsorption of horse heart cytochrome c onto the tentacle-type cation exchanger LiChrospher 1000 SO3- at pH 4.00 showed an isotherm of rectangular form. In this case the Langmuirean model is not applicable. In this paper, we propose an alternative way to deal with this situation, whereby the adsorption capacity of the adsorbent with a defined protein sample is studied as a function of displacing-ion concentration. The experimental conditions over defined ranges are then selected in order to relate this function to the change in the Gibb's free energy for the interaction between the protein and the ion exchanger. Additional comments about the general utility of the on-line adsorption vessel system employed to determine the adsorption isotherms are also made.

Adsorption↗
PubMed1970

Topography of nucleic acid helices in solutions. The interaction specificities of optically active amino acid derivatives.

The synthesis and interactions of the d- and l-enantiomers of the amino acid amide derivatives [Formula: see text] (I) and lysyl dipeptides [Formula: see text] (II) with poly rI.poly rC, poly rA.poly rU and calf thymus DNA is reported. The following results were found. (1) The degree of stabilization of the helices as measured by the T(m) (;melting' temperature) of the helix-coil transition was dependent on the nature of the amino acid. (2) For the poly rI.poly rC helix, the l-enantiomers of salts (I) and (II) stabilized more than the d-enantiomers. The same was true for calf thymus DNA in the presence of salts (II) and for poly rA.poly rU in the presence of salts (II) and the proline derivatives of salts (I). (3) As R increased in size and became more apolar, the amount of stabilization of the poly rI.poly rC helix in the presence of salts (I) decreased. On the other hand, the amount of stabilization increased with more polar substituents. An attempt was then made to determine whether the difference in stabilization of the double-stranded helices at the T(m) in the presence of the l- and d-enantiomers of salts (I) is due to the interaction with the helix, the random coil or both. A new method was developed for determining the binding of small ions to polyions that involves a competition between an insoluble polystyrene ion-exchange resin and the soluble polyion for the counterion. Dissociation constants are obtained for the complexes of single- and double-stranded helices with the salts (I). The results are illuminating and indicate that with certain helices, i.e. poly rA.poly rU, the interactions of salts (I) with the single strands may not be ignored. It is concluded that the high optical specificity found in Nature, i.e. d-ribose in nucleic acids and l-amino acids in proteins, cannot be attributed solely to monomer-polymer interactions described by Gabbay (1968).

Amides↗