Spectrophotometric determination of germanium by phenylfluorone

Spectrophotometric studies on the reaction between germanium ions and phenylfluorone were discussed including the reaction condition to develop a spectrophotometric method for the determination of germanium. The absorbance was measured at 525 nm after 20 min from the moment of adding the reagent. Beer's Law is obeyed, the relative standard deviation is 2%, the senstivity of the method is 2.55 × 10⁻³ mg/cm³, and the molar absorbtivity based on germanium is 1.75 × 10³.     

Structure investigation of mesalazine drug using thermal analyses,mass spectrometry,DFT calculations,and NBO analysis

Mesalazine (MZ) drug has been used for several decades as a primary treatment for inflammatory bowel diseases. The drug was investigated using thermal analysis (TA) measurements and electron impact mass spectral fragmentation at 70 and 15 eV of electron energy. The optimum molecular geometry and the total energy of the neutral and the positively charged MZ molecules were calculated by density functional theory method with 6-311++G(d,p) basis sets. Stability of the molecules arising from hyperconjugative interactions, charge delocalization, and the natural atomic charges has been analyzed using natural bond orbital analysis. In electron ionization mass spectrometry, the primary rupture is due to successive loss of H₂O (OH from carboxyl and H from phenolic OH of the ring) and CO of the acetyl group. Thermogravimetric results have revealed two stages of mass loss at 75.3 and 25.3 % in ranges 225–350 and 350–650 °C, respectively. The first one may be due to successive losses of different groups or molecules with fast rate of decomposition. A comparison between MS and TA helped in selection the proper pathway representing the fragmentation mechanism of this drug.     

High precision delta(17)O isotope measurements of oxygen from silicates and other oxides: method and applications

The use of infrared laser-assisted fluorination to release oxygen from milligram quantities of silicates or other oxide mineral grains is a well-established technique. However, relatively few studies have reported the optimisation of this procedure for oxygen-17 isotope measurements. We describe here details of an analytical system using infrared (10 μm) laser-assisted fluorination, in conjunction with a dual inlet mass spectrometer of high resolving power ( approximately 250) to provide (17)O and (18)O oxygen isotope measurements from 0.5-2 mg of silicates or other oxide mineral grains. Respective precisions (1) of typically 0.08 and 0.04 per thousand are obtained for the complete analytical procedure. Departures from the mass-dependent oxygen isotope fractionation line are quantified by Delta(17)O; our precision (1) of such measurements on individual samples is shown to be +/-0.024 per thousand. In turn, this permits the offset between parallel, mass-dependent fractionation lines to be characterised to substantially greater precision than has been possible hitherto. Application of this system to investigate the (17)O versus (18)O relationship for numerous terrestrial whole-rock and mineral samples, of diverse geological origins and age, indicates that the complete data set may be described by a single, mass-dependent fractionation line of slope 0.5244+/- 0.00038 (standard error). Copyright 1999 John Wiley & Sons, Ltd.     

Copper and iron interactions with angiotensin-converting enzyme inhibitors. A study by fast-atom bombardment tandem mass spectrometry

Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd.     

Solid phase selective separation and green preconcentration of Cu, Zn, Pb and Cd in drinking water by using novel functionalized resin

A new solid — phase extraction sorbent was developed based on stepwise anchoring of two ligand molecules for the determination of copper, zinc, lead and cadmium in drinking water by flame AAS. Amberlite XAD-2 functionalized with 4′-(2-hydroxyphenylazo)-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one (HPAPyr) was utilized for preconcentration/separation of these elements. The sorbent was prepared by two successive azo coupling reactions. First, 2-aminophenol was anchored to the amino groups in the resin resulted from nitration followed by reduction. Then, the resulted 2-aminophenol functionalized resin was further diazotized and coupled to the pyrazolone compound and the final product HPAPyr-XAD-2 was characterized by IR and elemental analysis. The optimum pH range for sorption, shaking time, exchange capacity, sample flow rate, preconcentration factor and interference from co-existing ions were investigated. All metal ions were quantitatively desorbed from the resin by 4.5 mol L⁻¹ nitric acid solution. The sorbent provides limit of detection within the range 0.9–3.3 μg L⁻¹ and concentration factor up to 250. The procedure was validated by analysis of certified material NIST-SRM 1577b. Application to drinking water showed satisfactory results with relative standard deviation RSD ≤ 8.5%.      

Separation and determination of trace amounts of zinc, lead, cadmium and mercury in tap and Qaroun lake water using polyurethane foam functionalized with 4-hydroxytoluene and 4-hydroxyacetophenone

A stable chelating sorbent was synthesized by covalently linking 4-hydroxytoluene or 4-hydroxyacetophenone with the polyurethane foam (PUF) through -NN- group. The synthesized chelating sorbents were characterized by IR and UV/vis measurements. The modified foams show excellent stability towards various solvents. Factors influencing the extraction process of Zn(II), Pb(II), Cd(II) and Hg(II) were studied and evaluated as a function of pH of metal ion solution and equilibration shaking time. The values of sorption capacity of metal ions (μg g⁻¹) were determined with the two types of bonded foams. The two phenolic bonded foams were studied comparatively. The potential applications of the two newly synthesized foams for the removal and separation of the examined metal ions from two natural water samples (drinking tap water and Qaroun lake water at Fayoum City, Egypt) were investigated. Precision (assessed as a relative standard deviation, R.S.D.) was also evaluated and found to be ≤7.3% (N = 5) with a detection limit under 0.46 μg L⁻¹.     

以脉冲萃取柱利用三异辛胺从高浓度铀溶液中回收铀

利用三异辛胺(TOA)纯化Gattar小型试验工厂的高浓度铀溶液(洗脱液的铀浓度7 g·L^-1),研究了脉冲萃取柱的性能。利用实验室级脉冲萃取柱进行了实验室规模的溶剂萃取实验和后续实验。结果表明,在室温、pH=1和有机相与水相的比例(V_O/V_A)约为1.8：1时,加入二(2-乙基己基)磷酸(D2EHPA)使其与TOA的比例(V_D2EHPA/V_TOA)为2：3,可使萃取克服Cl-的抑制效应,提高效率。将结论用于考察试验工厂级萃取柱的流体力学和传质性能,结果表明用脉冲萃取柱萃取铀可以达到97%的萃取效率,具有可行性。     

Kinetics and mechanism of oxidation of tris(ethylenediamine)-chromium(III) by N-bromosuccinimide

Summary In aqueous solutions, [Cr(en)₃]³⁺ aquates to [Cr(en)₂-(H₂O) ₂]³⁺. A kinetic study of the oxidation of [Cr(en)₃]³⁺ by N-bromosuccinimide (NBS) in aqueous solutions and water-alcohol solvent mixtures was performed. The reaction is first order with respect to both total [Cr^III] and [NBS]. The rate is inversely dependent upon [H⁺] in the 7.0–7.9 pH range, and varies with the co-solvent according to the order: MeOH > EtOH > PrOH. An appropriate mechanism, in which the deprotonated [Cr(en)₂(OH)(H₂O)]²⁺ is the reactive species, is suggested. Thermodynamic activation parameters have been calculated.Abstracted from the PhD thesis (Ain Shams University) of A. E.- D. M. Abdel-Hady.     

Zum Aufbau der Systeme V—(Fe,Co, Ni)—N

The constitution of the ternary systems V–Fe–N, V–Co–N, and V–Ni–N has been investigated by X-raymethods, metallographically and partly by microprobe analysis. Isothermal sections are presented for 1100°C and 1200°C respectively. Ternary complex nitrides have been observed in the systems V–Co–N and V–Ni–N. The compounds with formula V₄Co₂N (a=10.88–10.83±0.01 Å) and V₄Ni₂N (a=10.88–10.86±0.01 Å) crystallize with the partly filled Ti₂Ni-structure.

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