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Mixture Containing (mixture + containing)

Distribution by Scientific Domains
Chemistry60%
Life Sciences40%

Selected Abstracts

Novel negatively charged tentacle-type polymer coating for on-line preconcentration of proteins in CE

ELECTROPHORESIS, Issue 4 2009
Liang Xu
Abstract A novel negatively charged tentacle-type polymer-coated capillary column was fabricated and applied for on-line extraction and preconcentration of proteins. The polymer coating was prepared by glycidyl-methacrylate graft polymerization in a silanized capillary column and the following sulfonic acid group functionalization. It had high surface area and offered high phase ratio for protein adsorption. In addition, the polymer-coated capillary column provided more stable EOF than a bare uncoated capillary. These features of the polymer coating facilitated the extraction of proteins through electrostatic interactions. This was used to extract proteins. The extracted analytes were then desorbed and focused by EOF in the direction opposite to the sample injection flow for subsequent CE. With this procedure, over 1500-fold sensitivity enhancement was realized for myoglobin (MB) as compared with a normal capillary zone electrophoresis. By comparison of the peak areas of the enriched protein, it was found that the polymer-coated column could capture proteins about 30 times more than the uncoated column. In addition, the separation of a protein mixture containing 0.4,,g/mL of MB and 0.4,,g/mL of insulin was demonstrated by the on-line preconcentration and electrophoretic separation with the polymer-coated column. [source]

hypercloso -Hexa(amino)hexaboranes: Structurally Related to Known hypercloso -Dodecaboranes, Metastable with Regard to Their Classical Cycloisomers

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 36 2009
Wahid Mesbah
Abstract B6(NMe2)6 (2a) is the first neutral hypercloso -hexaborane to be characterized by X-ray structural analysis. The geometry of 2a is in nice agreement with that of the Ci symmetric molecule computed at the B3LYP/6-311+G** level of theory. Two B3 triangles with long B···B distances in 2a are reminiscent of those in Hawthorne's benzyloxy-substituted hypercloso -dodecaboranes 6a,b. Upon heating to 200 °C, 2a transforms into Nöth's classical cyclohexaborane 1a. Computations at the B3LYP/6-311+G** + ZPE level of theory show 1a to be 21.6 kcal,mol,1lower in energy than 2a, that is, the latter is metastable. hypercloso -Hexaborane B6(NEt2)6 (2b), which was reported to be thermodynamically more stable than 1b, is computed to be 22.4 kcal,mol,1less stable than 1b. Pure 1b is shown here not to transform into 2b upon standing in solution, which is in contrast to reports in the literature for a mixture containing 1b. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Solution NMR and X-Ray Structural Studies on Phthalocyaninatoiron Complexes

HELVETICA CHIMICA ACTA, Issue 8 2006
Ignacio Fernández
Abstract The addition of primary amines as solubilizing reagents for phthalocyaninatoiron complexes is shown to afford six-coordinate bis(amine)phthalocyaninato complexes, i.e., [Fe(amine)2(pc)] 2 (amine,=,decan-1-amine) and 3 (amine,=,benzylamine), with the two new N-donors occupying the trans -axial positions. The new complexes were characterized by extensive NMR measurements in THF solution. For complex 3 with the benzylamine ligand, the solid-state structure was determined by X-ray diffraction methods. Complex 2 is sufficiently labile in THF solution to exchange one amine ligand against CO (gas) affording an equilibrium mixture containing [Fe(amine)(CO)(pc)] 4. [source]

Cobalt removal from waste-water by means of supported liquid membranes

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2009
Kim Verbeken
Abstract BACKGROUND: Supported liquid membranes (SLM) are an alternative technique to remove and recover metals from diluted process solutions and waste-water. In the present work, the removal of Co(II) from a synthetic CoSO4 solution containing initial amounts of cobalt(II) in the range 100,200 ppm (0.1,0.2 g dm,3) has been studied on a pilot scale. By performing batch equilibrium experiments, the optimal settings, i.e. the composition of the organic phase, the pH of the feed, the type and concentration of the stripping agent were determined. RESULTS: It is shown that the equilibrium characteristics of a synergistic extractant mixture containing di-2-ethyl-hexylphosphoric acid (D2EHPA) and 5-dodecylsalicylaldoxime (LIX 860-I) are superior to D2EHPA. Both hydrochloric acid and sulfuric acid have been evaluated as stripping solutions in liquid,liquid extraction tests and as the receiving phase in a SLM configuration. Although equilibrium tests showed no difference in stripping characteristics between both chemicals, it was observed that in a SLM configuration the stability of the system when hydrochloric acid is used is poor. With a commercially available SLM module (Liqui-Cel Extra-Flow 4 × 28) having a surface area of 19 m2, a steady Co(II) flux of 0.140 gm,2h,1 has been obtained at influent concentrations of cobalt between 100 and 200 ppm with 3 mol dm,3 sulfuric acid as stripping phase. CONCLUSIONS: The results obtained show that a supported liquid membrane containing a synergistic mixture of LIX 860-I and D2EHPA gives the possibility of recovering cobalt from dilute solutions. Copyright © 2008 Society of Chemical Industry [source]

A hexamer peptide ligand that binds selectively to staphylococcal enterotoxin B: isolation from a solid phase combinatorial library

CHEMICAL BIOLOGY & DRUG DESIGN, Issue 2 2004
G. Wang
Abstract:, By screening a solid-phase combinatorial peptide library, a short peptide ligand, YYWLHH, has been discovered that binds with high affinity and selectivity to staphylococcal enterotoxin B (SEB), but only weakly to other SEs that share sequence and structural homology with SEB. Using column affinity chromatography with an immobilized YYWLHH stationary phase, it was possible to separate SEB quantitatively from Staphylococcus aureus fermentation broth, a complex mixture of proteins, carbohydrates and other biomolecules. The immobilized peptide was also used to purify native SEB from a mixture containing denatured and hydrolyzed SEB, and showed little cross-reactivity with other SEs. To our knowledge this is the first report of a highly specific short peptide ligand for SEB. Such a ligand is a potential candidate to replace antibodies for detection, removal and purification strategies for SEB. [source]