Analysis of acyclovir by high performance capillary electrophoresis with on-column amperometric detection

The separation of acyclovir (ACV) by high performance capillary electrophoresis (HPCE) with on-column amperometric detection using alpha-amino-5-mercapto-3,4-dithiazole (AMD) as internal standard is described. The calibration line was linear in the range of 0.5-20 mg/L of ACV. The detection limit was 0.15 mg/L of ACV. Its recovery ranged from 98 to 101% with relative standard deviations (RSDs) from 1.9 to 3.2% (n = 5). This method was successfully used for determining ACV in some pharmaceuticals and human urine. Comparable results with HPCE with ultraviolet (UV) detection and amperometric detection were obtained.     

Solvothermal Synthesis, Crystal Structure, and Properties of the First Zinc Containing Thioantimonate(III) [Zn( tren)] 2Sb 4S 8·0.75 H 2O

Yellow crystals of the title compound were obtained under solvothermal conditions reacting elemental Zn, Sb, and S in a solution of tris(2-aminoethyl)amine (=tren) and water. The compound crystallises in the monoclinic space group P2₁/c with a=13.0247(7), b=22.308(2), c=12.1776(6) Å, and =105.352(6)°. In the structure of [Zn(tren)]₂Sb₄S₈·0.75 H₂O two [Zn(tren)]²⁺ cations are bound to the [Sb₄S₈]^4– anion via S atoms. The Zn²⁺ ions are in a trigonal bipyramidal environment of four N atoms of the tetradentate tren ligand and one S atom of the [Sb₄S₈]^4– anion. The anion is formed by SbS₃ and SbS₄ units which share common corners and edges. The interconnection mode yields three different non-planar Sb₂S₂ heterorings. The shortest intermolecular Sb–S distance amounts to about 3.7Å, and taking this long separation into account undulated chains running along [001] are formed with the water molecules residing in the pocket-like cavities. Upon heating the compound decomposes in one step starting at about 240°C. The final decomposition product was identified as ZnS and Sb₂S₃ by X-ray powder diffractometry. Additionally, spectroscopic data as well as synthetic procedures for [Zn(tren)]₂Sb₄S₈·0.75 H₂O are reported.     

Effect of operating parameters on selective separation of heavy metals from binary mixtures via polymer enhanced ultrafiltration

Performance of continuous polymer enhanced ultrafiltration (PEUF) method was investigated for removal of mercury and cadmium from binary mixtures. This method includes the addition of polyethyleneimine (PEI) as a water soluble polymer to bind the metals, which was followed by ultrafiltration operation performed on both laboratory and pilot scale systems. The influence of various operating parameters such as temperature, metal/polymer ratio, presence of calcium ions and pH on retention of metals and permeate flux was investigated. To investigate the possibility of selective separation of mercury and cadmium, experiments were conducted for binary solutions at different pH and loading ratios. It was seen that the retention of mercury decreased and permeate flux increased when the temperature increased. The increased pH and decreased metal/polymer ratio, loading (L), resulted in higher retention of both metals. Shapes of retention vs. pH or L curves were very similar for both metals. Retentions stay almost constant at a value very close to unity until a critical L or pH value was reached, then, R decreases almost linearly with L or pH. However, retention of cadmium was affected more than that of mercury as the pH decreased and L increased. This leads to the selective separation of mercury and cadmium. At low pH values (about 5) and at high L values (about 0.3), mercury was removed by ultrafiltration operation while almost all cadmium passed through the membrane. At pH 5.5 and cadmium/polymer ratio about 0.35 and mercury/polymer ratio about 0.39, the highest separation factor was obtained as 49.     

Molecular simulation of water behaviors on crystal faces of hydroxyapatite

The water behavior on (001) and (100) crystal faces of hydroxyapatite (HAP) were studied using molecular dynamics (MD) simulations. The study showed that the water molecules between the HAP faces were under conditions of strong electrical field and high pressure, and hence formed 2–3 well-organized water layers on the crystal surfaces. These structured water layers had ice-like features. Compared with the crystallographic [100] direction of HAP, the polarity along the [001] direction was stronger, which resulted in more structured water layers on the surface. The interaction of water molecules with the calcium and phosphate sites at the HAP-water interface was also studied. The results indicated the multiple pathways of water adsorption onto the HAP surfaces. This study revealed the formation and the detailed structure of water layers on HAP surfaces and suggested that the interfacial water played an important role in stabilizing the HAP particles in aqueous solutions. Translated from Chinese Journal of Inorganic Chemistry, 2006, 22(8): 1392–1400 (in Chinese)     

ADSORPTION OF 2,4-DICHLOROBENZOXYACETIC ACID ONTO HYPERCROSSLINKED RESIN MODIFIED BY PHENOLIC HYDROXYL GROUP (AM-1)

INTRODUCTIONAdsorption has been considered to be the best available technology for removing organics from water in the USSafe Drinking Water Act[1]. Due to many drawbacks of activated carbon[2-7], the most widely used adsorbent,hypercrosslinked polymeric adsorbents developed by Tsyurupa and Davankov[8] have been increasingly viewedas an alternative to activated carbon for selective removal of specific organic substances from contaminatedwater[9-12], and series of researches have been do…     

High-efficiency, environment-friendly electroluminescent polymers with stable high work function metal as a cathode: green- and yellow-emitting conjugated polyfluorene polyelectrolytes and their neutral precursors

A series of aminoalkyl-substituted polyfluorene copolymers with benzothiadiazole (BTDZ) of different content were synthesized by Suzuki coupling reaction, and their quaternized ammonium polyelectrolyte derivatives were obtained through a postpolymerization treatment on the terminal amino groups. Copolymers are soluble in environmentally friendlier solvents, such as alcohols. It was found that the efficient energy transfer occurs by exciton trapping on the narrow band gap BTDZ site under UV illumination. Only 1% of BTDZ content is needed to completely quench a fluorene emission for both the neutral and the quaternized copolymers in the neat film. Absolute PL efficiencies of copolymer films were greatly enhanced as a result of the suppression of excimer formation. Light-emitting devices fabricated from these copolymers show high external quantum efficiencies over 3% and 1% for the neutral precursor and the quaternized copolymers, respectively, with high work function metals such as Al as a cathode. To the best of our knowledge, this is the first report on an electroluminescent polymer which bears the high EL efficiency, the electron-injection ability from high work function metals, and the solubility in environment-friendly solvents at the same time. These features make them a promising candidate for the next generation of light-emitting copolymers in PLED flat panel display application.     

水热法合成Ce0.67Zr0.33O0.2固溶体研究

采用两种不同前驱体通过水热法合成了Ce0.67Zr0.33O0.2固溶体,并通过XRD,BET,TPR等手段考察了样品的相结构,比表面及还原特性.结果表明,在180℃,12 h的水热条件下,以共沉淀产物为前驱体所制得的Ce0.67Zr0.33O0.2固溶体比表面积较高,但存在一定程度的相分离;以凝胶产物为前驱体制得的Ce0.67Zr0.33O0.2固溶体结构更完整,具有良好的还原特性及热稳定性.     

C9‐Iridoids from Scrophularia buergeriana

Four new iridoids, buergerinins B–E ( 1 – 4 ), along with three known iridoids, were isolated from the roots of Scrophularia buergeriana. Their structures were identified on the basis of spectroscopic analysis.     

Photopolymerization induced by a benzophenone derivative photoinitiator

A benzophenone derivative photoinitiator, HBP-TDI-HQ-TDI-HBP （HTCTH）, was synthesized based on 4-hydroxy benzophenone （HBP）, toluene-2,4-diisocyanate （TDI） and hydroquinone （HQ）. HTCTH was a more effective photoinitiator which had longer wavelength absorption in the UV-vis absorption spectra than the low molecular counterpart benzophenone （BP）. It showed that both rate of polymerization （Rp） and final conversion （P） increased with increase of amine and HTCTH concentration in photopolymerization.