Anion Exchange Chromatography Of Extracts Research Articles

Separation of Pertechnetate from Uranium in a Simulated UREX Processing Solution Using Anion Exchange Extraction Chromatography

A process to separate technetium from uranium in a simulated process solution resulting from the uranium extraction (UREX) process was demonstrated using a new extraction chromatographic (EC) resin from Eichrom Technologies. The Weak Base ECTM resin contains a tertiary amine incorporated into a macroporous resin bead support. The resin provided a good separation of pertechnetate from a 100 g/L uranyl(VI) nitrate solution representative of a UREX feed solution. The resin appeared quite stable to multiple uses. The elution of Tc from the resin was substantially improved over previous anion exchangers used. The eluted pertechnetate and ammonium nitrate solution was mixed with a reducing agent and gradually heated under an argon flow and then an argon/H2O flow to recover the Tc as the metal (96% yield). The U was precipitated with ammonium hydroxide and recovered as U3O8 (98% yield).

Determination of technetium-99 in soils and radioactive wastes using ICP-MS

AbstractThree methods have been used for the determination of 99Tc in soils and solid radioactive wastes using 99mTc as a yield monitor. In the method one and three the samples were leached in low concentrated nitric and sulphuric acid. Many contaminants were then co-precipitated with Fe(OH)3 in alkali media and Tc in the supernatant was separated using anion-exchange extraction chromatography. There were made also some studies how to improve the chemical recovery of 99mTc in the process of chromatography. In the method two the sample was ashed and then leached in 8 mol dm−3 HNO3 and after iron precipitation, technetium was separated on chromatographic column. The chemical recovery of 99mTc was optimized in the process of chromatography and leaching. Typical recoveries of technetium determined with 99mTc tracer for all these methods were in the range 39 %–87 %.The 99Tc activity was measured using proportional low-background beta detector after one week of staying to allow decay of 99mTc activity. 99Tc was also determined by the non-radiometric method using inductively coupled plasma mass spectrometer.

PCF11 encodes a third protein component of yeast cleavage and polyadenylation factor I.

Cleavage and polyadenylation factor I (CF I) is one of four factors required in vitro for yeast pre-mRNA 3'-end processing. Two protein components of this factor, encoded by genes RNA14 and RNA15, have already been identified. We describe here another gene, PCF11 (for protein 1 of CF I), that genetically interacts with RNA14 and RNA15 and which presumably codes for a third protein component of CF I. This gene was isolated in a two-hybrid screening designed to identify proteins interacting with Rna14 and Rna15. PCF11 is an essential gene encoding for a protein of 626 amino acids having an apparent molecular mass of 70 kDa. Thermosensitive mutations in PCF11 are synergistically lethal with thermosensitive alleles of RNA14 and RNA15. The Pcf11-2 thermosensitive strain shows a shortening of the poly(A) tails and a strong decrease in the steady-state level of actin transcripts after a shift to the nonpermissive temperature as do the thermosensitive alleles of RNA14 and RNA15. Extracts from the pcf11-1 and pcf11-2 thermosensitive strains and the wild-type strain, when Pcf11 is neutralized by specific antibodies, are deficient in cleavage and polyadenylation. Moreover, fractions obtained by anion-exchange chromatography of extracts from the wild-type strain contain both Pcf11 and Rna15 in the same fractions, as shown by immunoblotting with a Pcf11-specific antibody.

The GDP-bound form of the small G protein Rac1 p21 is a potent activator of the superoxide-forming NADPH oxidase of macrophages.

Phagocytes produce superoxide by the assembly of a multicomponent complex that utilizes NADPH for the reduction of molecular oxygen (NADPH oxidase). The components participating in the assembly are a membrane-bound flavocytochrome and three cytosolic proteins, one of which was shown to be a dimer of the small GTP-binding protein (G protein) Rac1 p21 or Rac2 p21 with GDP dissociation inhibitor for Rho (Rho GDI). We determined the identity and quantity of the nucleotide bound to Rac1 p21 by high performance anion exchange chromatography of extracts prepared from highly purified Rac1 p21-Rho GDI, isolated from guinea pig macrophage cytosol. Rac1 p21 contained only GDP at a ratio of close to 1 mol of GDP per mol of G protein. The GDP-bound form of Rac1 p21 complexed to Rho GDI functioned as a potent activator of NADPH oxidase in a cell-free system that contained no free GTP or ATP. We propose that the GDP-bound form of Rac1 p21 might be the physiological activator of NADPH oxidase in macrophages, following its dissociation from Rho GDI, and that nucleotide exchange or conversion to GTP is not necessarily involved.

Some properties of starch branching enzyme from indica rice endosperm ( Oryza sativa L.)

Starch branching enzyme (α-1,4-glucan: α-1,4-glucan-6-glycosyl transferase; EC 2.4.1.18) catalyzes the formation of the α-1,6-bond in branched starch molecules such as amylopectin. Some characteristics of starch branching enzyme in rice endosperm ( Oryza sativa L.) were determined because of the importance of starch structure for rice quality. Two or three peaks of starch branching enzyme activity were resolved by anion-exchange chromatography of extracts from high amylose rice. The properties of rice starch branching enzyme were similar to those found for the enzyme from other plant sources except for a much lower molecular weight. Rice branching enzyme had an apparent molecular weight of 40 000 as estimated by gel permeation chromatography. Multiple forms of starch branching enzyme could also be resolved in milled rice, suggesting that relationships between starch quality and characteristics of starch branching enzyme could be examined in the mature grain after harvest.

Enflurane biotransformation in humans

The biotransformation of enflurane was investigated in humans. Liquid anion exchange chromatography of extracts of urine obtained during and following enflurane anesthesia revealed the presence of two organic fluoride containing enflurane metabolites. Gas chromatographic-mass spectroscopic analysis of lyophilized urine extracts indicated the presence of 2-difluoromethoxy- 2,2-difluoro-acetic acid. These results suggest that enflurane undergoes both oxidative dechlorination at the β carbon and O-demethylation at the ether linkage in humans.

Daucic acid and its occurrence in plants.

DURING anion-exchange chromatography of extracts of biological materials, acidic non-nucleotide contaminants of the nucleotide fraction have often been encountered. They are usually identified by their characteristic ultraviolet absorption maxima. Thus the leaves of maize (Zea mays) were shown to contain chelidonic acid1, the leaves of wheat (Triticum sativum) trans-aconitic acid (unpublished results of A. J. K., and M. J. Cornelius) and certain animal tissues ascorbic acid2. These compounds were present in sufficient quantities to interfere with ultraviolet analysis of the chromatographic fractions. During a study3 on the free nucleotides of the root of carrot (Daucus carota) another contaminant was observed with a maximum at 240 nm. The spectrum did not change with pH until decomposition occurred in highly acid media. The contaminant was eluted with adenosine diphosphate which indicated a strong or multibasic acid.