Dowex 1X8 Research Articles

Multielement radiochemical neutron activation analysis of high purity aluminium

A radiochemical neutron activation analysis technique for the determination of 51 elements in high purity aluminium via medium- and long-lived indicator radionuclides has been developed. It is based on a separation procedure involving the removal of 24Na, produced via the reaction 27Al(n,α), on a hydrated antimony pentoxide column and further separation of the radionuclide mixture into 11 groups on two Dowex 1X8 columns and one Dowex 50X8 column from HCl/HF and HCl media as well as the extraction of copper with APDTC in chloroform. The indicator radionuclides for the significant impurities thorium and uranium, 233Pa and 239Np, were separated with satisfactory selectivity in one fraction. For 43 elements, the limits of detection are <10 ng/g, for thorium and uranium, they are 50 pg/g. The method was applied to the analysis of different high purity aluminium samples. For a number of elements, the results of this technique are compared with those of other techniques.

Fructofuranose 2-phosphate is the product of dephosphorylation of fructose 2,6-bisphosphate

Using comparative ion-exchange chromatography on Dowex 1X4, the product of dephosphorylation of fructose 2,6-bisphosphate with purified yeast fructose-2,6-bisphosphate 6-phosphohydrolase, was shown to be identical to the furanose form of fructose 2-phosphate prepared by chemical synthesis according to Pontis and Fischer [Biochem. J. 89, 452-459 (1963)]. As expected for the furanose form of fructose 2-phosphate, the enzymatically formed product consumes 1 mol periodate/mol fructose 2-phosphate, whereas the chemically synthesized pyranose form consumes 2 mol periodate/mol. In addition, it is shown that the enzymatic product behaves identically to the furanose, not the pyranose, form of fructose 2-phosphate in hydrolysis of the ester bond at pH 4 and 37 degrees C, as described previously for the chemically synthesized compounds [Pontis and Fischer (1963) vide supra].

ChemInform Abstract: Synthesis of 6′‐Aminohexyl 2‐Acetamido‐2‐deoxy‐D‐galactoside Isomers and a Unique Isomerization Catalyzed by Ion Exchange Resin.

Abstract The 6-aminohexyl α- and β-pyranosides and β-furanoside of 2-acetamido-2-deoxy-D-galactose (N-acetyl-D-galactosamine) were prepared. N-Acetyl-D-galactosamine was reacted with acetyl chloride in the cold. The per-O-acetyl 1-chloro derivative was then reacted with 6-(N-trifluoroacetyl) aminohexanol in the presence of mercuric cyanide. Glycoside products were isolated by gel chroraatography, de-O-acetylated, and de-N-trifluoroacety-lated. The β-pyranoside, which is the major product, was obtained in 29% overall yield, as well as the β-furanoside. The α-pyranoside was prepared in 70% overall yield by reacting 2-acetamido-1, 3, 4, 6-tetra-O-acetyl-2-deoxy-α-D-galacto-pyranose, which is a byproduct of the above synthetic scheme (22%), with 6-(N-trifluoroacetyl)aminohexanol in the presence of boron trifluoride etherate. A strong cation exchange resin (Dowex 50X8, H+ form) catalyzed interconversion of the β-furanoside and the β-pyranoside, with the latter predominating at equilibrium. The α-pyranoside was...

Synthesis of 6′-Aminohexyl 2-Acetamido-2-deoxy-D-galactoside Isomers and a Unique Isomerization Catalyzed by Ion Exchange Resin

Abstract The 6-aminohexyl α- and β-pyranosides and β-furanoside of 2-acetamido-2-deoxy-D-galactose (N-acetyl-D-galactosamine) were prepared. N-Acetyl-D-galactosamine was reacted with acetyl chloride in the cold. The per-O-acetyl 1-chloro derivative was then reacted with 6-(N-trifluoroacetyl) aminohexanol in the presence of mercuric cyanide. Glycoside products were isolated by gel chroraatography, de-O-acetylated, and de-N-trifluoroacety-lated. The β-pyranoside, which is the major product, was obtained in 29% overall yield, as well as the β-furanoside. The α-pyranoside was prepared in 70% overall yield by reacting 2-acetamido-1, 3, 4, 6-tetra-O-acetyl-2-deoxy-α-D-galacto-pyranose, which is a byproduct of the above synthetic scheme (22%), with 6-(N-trifluoroacetyl)aminohexanol in the presence of boron trifluoride etherate. A strong cation exchange resin (Dowex 50X8, H+ form) catalyzed interconversion of the β-furanoside and the β-pyranoside, with the latter predominating at equilibrium. The α-pyranoside was...

Sulfide determination by N,N-dimethyl-p-phenylenediamine immobilization in cationic exchange resin using an optical fiber system

A new method for sulfide determination is described in which its reaction with N,N-dimethyl-p-phenylenediamine immobilized on a solid support yields methylene blue. The reaction takes place on the cationic exchange resin Dowex 50-X8, and light reflected from the sample is focused through an optical fiber system. Because of the irreversibility of the process, an optical cell rather than a sensor was chosen to monitor the methylene blue concentration. Up to 0.06 ppm sulfide, a linear calibration graph is obtained, although strict adherence to conditions is required to attain reproducible results.

カキ果のアルコール抽出時におけるメチルおよびエチルβ‐Ｄ‐フルクトフラノシドの生成

Enzymatic formation of methyl and ethyl β-D-fructofuranosides was investigated in aqueous methanol and ethanol extracts of Japanese persimmon fruits. The fruits were extracted with 60% methanol or 40% ethanol at 20°C for 24 hr. The extracts were concentrated and submitted to Dowex 1X2 (OH) column chromatography, to separate methyl and ethyl β-D-fructofuranoside for 13C-NMR and polarimetric analysis. The invertase in the persimmon was active considering the high concentration of methanol and ethanol. The formation of β-D-fructofuranosides in the alcoholic extracts of the fruits was due to the action of invertase. In extraction at 20°C for 24 hr, 40_??_50% methanol gave 10_??_15% methyl, and 20% ethanol, 3_??_6% ethyl β-D-fructofuranosides, to total mono and oligo saccharides (free sugars).

Reinvestigation of compound X, a suspected biotin intermediate: identification of N-formyl derivatives of biotin and dethiobiotin.

Compound X, reported as an intermediate in the biosynthesis of biotin from dethiobiotin (DTB) (Biochem. Biophys. Res. Commun., 88, 312 (1979)), was found to contain N-formyl DTB and biotin. The methyl ester of N-formyl biotin was considered to be a product from the biotin, which was biosynthesized from DTB by resting cells of E. coli C 124, through treatment with diazomethane in the presence of a trace amount of formic acid after Dowex 1X2 column chromatography. NMR analysis revealed that biotin was formylated at 1'-N. N-Formylated DTB and biotin are new biotin derivatives.

Cobalt preconcentration on a nitroso-R salt functional resin and elution with titanium(III)

The anion exchange resin Dowex 1X8, converted to the nitroso-R salt form, was used for adsorbing cobalt from large freshwater samples. Strongly acid titanium(III) chloride 10/sup -2/ M solution was found very effective at 60/sup 0/C as a new eluant and yielded complete recovery with a preconcentration factor of 100. Subsequent atomic absorption spectrometry determination of cobalt in the eluate was possible with no interference from titanium, reduced organics, and iron, copper, and nickel which partially might be fixed onto the resin. The suggested procedure allows a reproducibility of 5-10% for samples with cobalt concentrations in the range of 0.01-1 ..mu..g L/sup -1/. 15 references, 2 figures, 3 tables.

Procedures for isolation and determination of thorium

The cation-exchange behaviour of micro and trace quantities of thorium on Dowex 50-X8 in the presence of carbonate and phosphate has been studied. Carbonate causes loss of thorium to the column effluent at pH ⩾ 10.In the presence of phosphate, thorium is incompletely sorbed in the pH range 2–4.5, the loss being maximum at pH 3.8. Outside this range, thorium is quantitatively sorbed and recovered. A method that does not employ ion-exchange has been developed for the microdetermination of thorium in phosphate solution. The phosphate is precipitated as bismuth phosphate and thorium is leached from the precipitate with ammonium carbonate solution and determined with Arsenazo III. Uranium, molybdenum and vanadium are removed with Alamine 336. The results obtained for a standard ore are in excellent agreement with the certified value.

Identification of new Sialic Acids Derived from Glycoprotein of Bovine Submandibular Gland

Improvements in the isolation procedure and the analytical equipment enabled the detection of seven novel sialic acids in bovine submandibular gland glycoprotein: N-acetyl-8-O-acetylneuraminic acid, N-acetyl-8,9-di-O-acetylneuraminic acid, N-acetyl-7,8,9-tri-O-acetylneuraminic acid, N-glycoloyl-7-O-acetylneuraminic acid, N-glycoloyl-7,9-di-O-acetylneuraminic acid, N-glycoloyl-8,9-di-O-acetylneuraminic acid, and N-glycoloyl-7,8,9-tri-O-acetylneuraminic acid. There are also indications for the presence of N-glycoloyl-8-O-acetylneuraminic acid. In addition, the sialic acids already known to occur in this tissue, namely N-acetylneuraminic acid, N-acetyl-7-O-acetylneuraminic acid, N-acetyl-9-O-acetylneuraminic acid, N-acetyl-7,9-di-O-acetylneuraminic acid, N-glycoloylneuraminic acid, and N-glycoloyl-9-O-acetylneuraminic acid could be identified. Sialic acids were released from the mucin by mild acid hydrolysis and prefractionated on a Dowex 2X8 anion-exchange column (formate form) by elution with a 0-0.6 M gradient of formic acid. The four pools of sialic acids obtained in this way were each further fractionated by column chromatography on cellulose with n-butanol/n-propanol/water (1/2/1, v/v/v) as eluent. By this procedure, N-acetylneuraminic acid, N-acetyl-7-O-acetylneuraminic acid, N-acetyl-9-O-acetylneuraminic acid, N-glycoloylneuraminic acid, and N-glycoloyl-9-O-acetylneuraminic acid were obtained in pure form. The other sialic acids could be enriched sufficiently in different fractions for structural identification. Analyses of sialic acids were carried out by one-dimensional and two-dimensional thin-layer chromatography, gas-liquid chromatography, and gas-liquid chromatography-mass spectrometry.

Quantitation of l- glycero- d- manno-heptose and 3-deoxy- d- manno-octulosonic acid in rough core lipopolysaccharides by partition chromatography

A partition chromatographic procedure utilizing a cationic exchange resin column in the Li + form and 90% ethanol as the mobile phase was employed to quantify 3-deoxy- d- manno-octulosonic acid (KDO) and l- glycero- d- manno-heptose in the lipopolysaccharides (LPS) of R e and R dP − rough mutants of Salmonella minnesota. In a standard mixture of monosaccharides, KDO eluted shortly after the void volume and heptose eluted after the neutral hexoses. Mild acid treatment of either the R e or R dP − LPS with 0.16 n methanesulfonic acid in the presence of Dowex 50-X8 resin (H + form) released more than 80% of the KDO residues within 15 min. The heptose of the R dP − LPS, first detected after 90 min of hydrolysis, increased gradually to a maximum level at 12 h. A secondary gradual increase in KDO became apparent during the heptose release. The weight contents of these two monosaccharides based upon aheir maximum values detected during hydrolysis were 20.3 ± 0.6% KDO, for the R e LPS, and 13.8 ± 0.4% KDO and 12.0 ± 0.4% heptose, for the R dP − LPS. The relationship between the kinetics of release of KDO and heptose and the nature of the linkages involving these two monosaccharides are discussed.

115Cd photonuclear production for115Cd−115mIn generator

Production of115Cd by means of photonuclear reaction and preparation of a115mIn generator, based on the genetic sequence of115Cd115mIn, were studied. The production rates of115Cd by the116Cd(γ, n)115Cd reaction were determined as a function of the maximum bremsstrahlung energies between 35 and 60 MeV. Then the parent,115Cd, was produced by irradiating about 0.15g of CdO with the bremsstrahlung from a 60 MeV-150 μA electron beam. After the parent in the Cd42− form was adsorbed on the Dowex 1x8 resin column, the daughter was eluted with a physiologic saline adjusted to pH 1. The generator was milked over a period of 3 days, during which time about 900 ml of eluent were allowed to flow through the column. Even after the milkings were repeated 15 times with 60 ml of the eluent, no115Cd was found in the115mIn fractions (the detection limit of inactive cadmium: 0.02 μg).

Element distribution coefficients for hydrofluoric acid/nitric acid solutions and the anion exchange resin Dowex 1X8

Element distribution coefficients for hydrofluoric acid/nitric acid solutions and the anion exchange resin Dowex 1X8

Determination of light rare earth elements in apatite by x-ray fluorescence spectrometry after anion exchange extraction

The results of an investigation, the purpose of which was to study the feasibility of analysis of La, Ce, Pr, and Nd in apatite minerals, utilizing x-ray fluorescence spectrometry (XRF), are discussed. After sample dissolution in HNO/sub 3/, rare-earth elements (REEs) are separated by a mixed solvent anion exchange using the batch extraction technique. The anion exchanger employed is the strongly basic resin Dowex 1X8, 100 to 200 mesh (nitrate form). REEs are fixed on the resin from a medium consisting of 95% CH/sub 3/OH-5% 7 M HNO/sub 3/ (v/v). The dried resin is uniformly spread over a disk of self-adhesive foil backed with a cellulose support. The thin resin film formed is then used for XRF analysis. Synthetic standards prepared following the same procedure are employed for calibration. Analytical results of two apatite samples are presented. Good correlation is obtained between XRF and neutron activation analysis data. Limits of detection, precision, and accuracy of the results are discussed.

Chromatographic behaviour of Cs+ in an ion exchange column

The cesium band traveling in an ion exchange column filled with Dowex 50X8 resin has been studied during elution with hydrochloric acid under different conditions. The dependence of the rate of band motion on the separation factor and on the flow rate of the eluent is given. Also the temperature dependence and the acid concentration dependence of the separation factor is shown.

Thermolytic digest of chicken pepsin

Chicken pepsin prepared by the activation of pepsinogen was digested with thermolysin. The thermolytic digest was fractionated by chromatography on Sephadex G-25 fine. Certain fractions were subsequently subjected to ion exchange chromatography on Dowex 50-X2. The final purification was effected by paper chromatography and high voltage electrophoresis. By these procedures a series of homogeneous peptides was obtained; of the latter 54 nonoverlapping (save for a few exceptions) peptides are described in this paper. These peptides in addition to the thermolytic peptides reported before represent 80% of the linear structure of the whole molecule. The N-terminal amino acid sequence of chicken pepsin is discussed from the viewpoint of the recent data obtained by the analysis of the thermolytic digest.

Binding of alditols to the hydroxyl form of dowex-1 XS, a strongly basic ion-exchange resin: an improved method for estimation of the degree of polymerization of neutral oligosaccharides and polysaccharides

The hydroxyl form of a strongly basic ion-exchange resin, Dowex-1 X8, had been used by Yamaguchi et al. to separate alditols from monosaccharides for estimation of the degree of polymerization (d.p.) of neutral oligosaccharides and polysaccharides, because alditols passed through a column of the resin, but monosaccharides were bound to it. However, the resin has now been found to adsorb not only monosaccharides but also alditols, and it is difficult to separate them readily. Therefore, this method for estimation of the d.p. of oligosaccharides has been improved. Elution of alditols from a column of Dowex-l X8 ( OH -) resin is influenced by methanol, ammonium acetate, and ammonium formate.

α- d-allopyranosyl β- d-fructofuranoside ( allo-sucrose) and its derivatives

Reduction of 3-ketosucrose ( 1) with sodium borohydride gave mainly α- d-allopyranosyl β- d-fructofuranoside ( 2) characterized as its octabenzoate. Using sodium borodeuteride, [3- 2 H] allo-sucrose ( 5) and [3- 2H]sucrose ( 6) were obtained in the ratio 12:1. The mixture was fractionated on Dowex-50 X8 resin (Ca 2+ form), and the [3- 2H] derivatives were isolated as their octa-acetates. Inspection of the 13C-n.m.r. spectra of 5 and 6 enabled the C-3 signals to be assigned. allo-Sucrose ( 2) was more readily obtained by oxidation of sucrose with dimethyl sulphoxide-acetic anhydride followed by reduction with sodium borohydride and fractionation on Dowex-50 X8 (Ca 2+) resin. Tritylation of 2 followed by acetylation gave, after chromatography, the 6,1′,6′-tritrityl ether ( 9, 10%), the 6,6′-ditrityl ether ( 10, 26%), and a mixture of monotrityl ethers (20%). Hydrogenolysis of 9 and 10 gave the penta-acetate and hexa-acetate, respectively, with no detectable migration of AcO-4. Treatment of 2 with sulphuryl chloride at -50° gave the 6,6′-dichloride.

Ion-exchange separation of lithium from large amounts of sodium, calcium, and other elements by a double column of Dowex 50-X8 and crystalline antimonic(V) acid

Ion-exchange separation of lithium from large amounts of sodium, calcium, and other elements by a double column of Dowex 50-X8 and crystalline antimonic(V) acid

Formation of a thiamine artifact during chromatography: A single column procedure for the separation of thiamine and the thiamine mono-, di-, and triphosphate esters

Chromatography of a preparation of [ 14C]thiamine pyrophosphate (thiamine-PP) on Dowex 1X8 in the formate form produced an unexpected peak, X-1, which was eluted just prior to the thiamine-PP peak. An ammonium formate, pH 4.5, gradient was the eluant. Rechromatography of either peak X-1 or thiamine-PP produced the same two peaks. The radioactive specific activity per micromole labile phosphate was the same for the two peaks. Peak X-1 appears to be a thiamine compound formed in the presence of formate solutions. This procedural artifact was circumvented by the substitution of acetate for formate. By varying the pH as well as the ionic strength a single column procedure has been developed that separates thiamine and the three phosphate esters quantitatively in micromolar amounts.