Chromatographic separation of neodymium isotopes by using chemical exchange process

The neodymium isotope effects were investigated in Nd–malate ligand exchange system using the highly porous cation exchange resin SQS-6. The temperature of the chromatographic columns was kept constant at 50 °C by temperature controlled water passed through the columns jackets. The separation coefficient of neodymium isotopes, ?’s, was calculated from the isotopic ratios precisely measured by means of an ICP mass spectrometer equipped with nine collectors as ion detectors. The separation coefficient, ? × 10⁵, were calculated and found to be 1.4, 4.8, 5.4, 10.6, 16.8 and 20.2 for ¹⁴³Nd, ¹⁴⁴Nd, ¹⁴⁵Nd, ¹⁴⁶Nd, ¹⁴⁸Nd and ¹⁵⁰Nd, respectively.     

Chromatographic analysis of chemical warfare agents

The usefulness and applications of the particular types of chromatography in the analysis of chemical warfare agents have been reviewed. A major problem in the chromatographic analysis of chemical warfare agents is the collection and preparation of the samples. The importance of this problem differs for the various types of chromatography. Significant differences occur in the way in which samples are collected from air, water, soil, vegetables or animal organisms. The analyses are characterized by the main groups of chemical warfare agents, e.g., organophosphorus, vesicants, irritants, etc. Account has been taken of the relationships between their properties and the possibilities of their chromatographic analysis. The advantages and disadvantages of particular types of chromatography in the analysis of the particular groups and individual agents have been considered. The detectability of particular chemical warfare agents has been assessed, together with the separating efficiency for their mixtures. Examples of applications of chromatographic systems and conditions of chromatographing are summarized in tables. It is concluded that chromatography is a very useful tool in the analysis of chemical warfare agents; GC and TLC have the most advantageous properties, HPLC being slightly inferior.     

Chromatographic separation of rare-earths by cation exchange

A simple relationship expressing the dependence of elution peak position shifts on change in eluant pH is developed for rare-earth ion-exchange separations using α-hydroxy-isobutyric,a-hydroxya-methyl butyric and lactic acids as eluants.     

Supramolecular polymers formed by cinnamoyl cyclodextrins

6-Cinnamoyl α-cyclodextrin (6-CiO-α-CD) and 6-cinnamoyl β-cyclodextrin (6-CiO-β-CD) were prepared. 6-CiO-α-CD formed intermolecular complexes to give supramolecular oligomers. 6-CiO-β-CD formed insoluble supramolecular complexes in the solid state. The structures of these complexes are discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3519–3523, 2003     

Aqueous biphasic systems formed by nonionic polymers I. Effects of inorganic salts on phase separation

The effect of salts KSCN, KI, KBr, KCl, KClO₄, KF, K₂SO₄ and NH₄Cl, LiCl, NaCl, KCl, CsCl on the binodials of the phase diagrams for aqueous biphasic dextranpolyvinylpyrrolidone, dextran-polyvinyl alcohol, dextran-ficoll and dextran-polyethylene glycol systems was studied. It is established that the K-salts present at the concentrations of 0.1 and 0.5 mol/kg alter the binodials of the phase diagrams for the above systems. The effect of a salt is found to be related to the lyotropy of the salt quantified by the salt molal surface tension increment. It is assumed that phase separation in an aqueous polymer biphasic system is affected by the presence of a salt mainly due to the effect of the salt on the structure and/or state of water in the system.     

Chromatographic separation of uranium

Summary A solvent mixture of methanol and saturated ammonium acetate solution (18:2) is employed for the separation of uranium in ppm quantities from iron (up to 1000 fold excess) by paper chromatography. The separation from both iron and copper can be achieved by using a solvent mixture of methyl ethyl ketone, acetic acid, and diluted nitric acid (1613).

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Zusammenfassung Zur papierchromatographischen Trennung von ppm-Mengen Uran von Eisen (in bis zu 1000 fächem Überschuß) wird ein Laufmittel aus Methanol und gesätt. Ammoniumacetatläsung (182) benutzt. Die Trennung von Eisen und Kupfer wird mit einem Gemisch aus Methyläthylketon, Essigsäure und verd. Salpetersäure (1613) durchgeführt.

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The author is highly thankful to Prof. Bh. S.V. Raghava Rao for his valuable suggestions and guidance throughout the progress of this work.Thanks are also due to the Department of Geology, Andhra University for supplying the samples and to the Counsil of Scientific and Industrial Research, New Delhi for the award of a fellowship.     

Chromatographic separation of the isomers formed in the low-temperature hydrogenation of cottonseed oil in solvents

Summary In order to determine the degree of unsaturation of fats and to study the kinetics of their hydrogenation, it is proposed to use instead of the iodine number an index which is called the unsaturation number and shows the total number of double bonds in 100 molecules of fatty acids.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 671–675, November–December, 1970.     

Multimonomer and cross-linked polymers formed by its copolymerization

Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to examine the thermal behavior of the multimonomer poly[2-(10-undecenoyloxy)ethyl methacrylate] (PUDEM) within the temperature range from -80 to 400°C. DSC measurements indicated that the polymer side chains were able to crystallize in paraffinic phase. PUDEM, added to methyl methacrylate (MM), can effectively copolymerize with essentially no homopolymer produced as shown by DSC (single T _g). The value of T _g depends on the PUDEM content, degree of cross-linking and the presence of free MM in the cross-linked product. This revised version was published online in August 2006 with corrections to the Cover Date.     

Chromatographic separation of isoflavones

The optimum ratios of the components of the solvent systems have been determined with the aid of the simplex-grid method of experimental planning and the separation of a number of isoflavones has been carried out with the aid of these systems in thin layers of silica gel (Silufol plates); in addition, the chromatographic constants of the functional groups have been determined, which makes it possible to obtain the R_f values of compounds under investigation in an analysis of plant material by a mathematical method.Pyatigorsk Pharmaceutical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 712–716, November–December, 1983.     

流动注射化学发光法测定青霉素G钾

在甲醛的存在下,酸性KMnO4与青霉素G钾能够产生很强的化学发光,从而建立了KMnO4-甲醛-青霉素G钾化学发光体系来测定青霉素G钾.青霉素G钾的测定线性范围为2.0×10-7～1.0×10-5 g/mL,方法的检出限为1.4×10-7 g/mL,对4.0×10-7 g/mL的青霉素G钾进行11次平行测定,相对标准偏差为1.0%,用此法测定青霉素G钾取得了较好的结果.     

Chromatographic separation of papain evaluated by immunochemical methods

The chromatographic separation of crude papain preparations on Sephadex G-50 (fine) enables pure papain to be obtained in a single step. Immunochemical techniques have been found to be very convenient for testing the purity of the individual chromatographic fractions. A general approach is presented that makes it possible to follow the course of the chromatographic purification of any immunogenic compound by simple qualitative immunochemical techniques that can be applied in any laboratory.     

Aqueous biphasic systems formed by nonionic polymers II. Concentration effects of inorganic salts on phase separation

Concentration effects of KSCN, KClO₄, KI, KBr, KNO₃, KCl, KF and K₂SO₄ on the compatibility of dextran with ficoll, polyvinylpyrrolidone and poly(ethylene glycol) at fixed polymer concentration ratios were studied in aqueous solution. The results obtained are considered in terms of the Patterson theory of-effect. It is assumed that phase separation in an aqueous solution of two nonionic polymers results from the appearance of two different water structures in the vicinity of the phase polymers. The data obtained are considered in terms of the concept of salting-in-salting-out effects of neutral salts on aqueous solubility of biopolymers. The salt effects observed are attributed to two antagonistic influences of salts on the electrostatic (dipole-dipole) polymer-water interactions and on the water-water interactions in the vicinity of the phase polymers.     

Surface-to-surface bridges formed by reversibly assembled polymers

Self-assembled polymers whose main chains are defined by reversible DNA base pairing form bridges between the tip of an atomic force microscope and substrate. The forces associated with the rupture of these assemblies are independent of polymer bridge length, and they resemble those expected for the isolated associations defining the polymer bridges. The assembly is reversible and is inhibited by a competitive, nonpolymerizing oligonucleotide. Noncomplementary polymer brush layers do not bridge, and therefore, the forces result from specific molecular recognition events. The length distribution of the bridges differs greatly from that of the polymers in solution, and thus the bridging is responsive to the spatial constraints of the environment.     

催化动力学光度法测定青霉素G及其机理研究

研究了在青霉素G存在下双氧水氧化苋菜红的褪色反应,建立了催化动力学光度法测定微量青霉素G的方法.方法线性范围为0.20～4.00μg/mL,回归方程y=-0.015p(μg/mL)+0.311,r=0.9998;方法线性范围为4.00～50.0μg/mL,回归方程y=0.001p(μg/mL)+0.280,r=0.99...     

Comparison of electrochemical properties of two-component C60-Pd polymers formed under electrochemical conditions and by chemical synthesis

The electrochemical behavior of C₆₀-Pd polymer formed under electrochemical conditions and by the chemical synthesis was examined. In these polymers, fullerene moieties are covalently bonded to palladium atoms to form a polymeric network. Both materials deposited at the electrode surface show electrochemical activity at negative potentials due to the reduction of fullerene cage. Electrochemically formed thin polymeric films exhibit much more reversible voltammetric response in comparison to chemically synthesized polymers. The morphology and electrochemical behavior of chemically synthesized C₆₀-Pd polymer depend on the composition of grown solution. Chemical polymerization results in formation of large, ca. 50 μm, crystallic superficial structures that are composed of regular spherical particles with a diameter of 150 nm. The capacitance properties of C₆₀-Pd films were investigated by cyclic voltammetry and faradaic impedance spectroscopy. Specific capacitance of chemically formed films depends on the conditions of film formation. The best capacitance properties was obtained for films containing 1:3 fullerene to Pd molar ratio. For these films, specific capacitance of 35 Fg^?1 was obtained in acetonitrile containing (n-C₄H₉)₄NClO₄. This value is much lower in comparison to the specific capacitance of electrochemically formed C₆₀-Pd film.     

Chiral supramolecular polymers formed by host-guest interactions

alpha-Cyclodextrin with a p-t-butoxyaminocinnamoylamino group in the 3-position (3-p-(t)()BocCiNH-alpha-CD) has been found to form a supramolecular polymer in an aqueous solution. The degree of polymerization of the supramolecular polymer is higher than 15 at 20 mM, as proved by VPO (vapor pressure osmometry) measurements and turbo ion spray TOF MS measurements. The existence of substitution/substitution interactions between adjacent monomers of the supramolecular polymer have been confirmed by the observation of positive and negative Cotton bands in circular dichroism spectra. The mechanism for the induction of the chirality was confirmed using model compounds. The substituents were found to exist as a left-handed anti configuration in supramolecular polymers. The supramolecular polymer was found to take a helical structure. The structure of the supramolecular polymer was observed by STM measurements.