Separation gallium-fer en presence d'edta

Macro- or microquantities of gallium can be separated from iron by precipitating the latter with sodium hydroxide in the presence of EDTA. Nearly all the gallium remains in solution. After the separation of iron, gallium is extracted with tributylphosphate from 3 N hydrochloric acid medium, and then re-extracted into water. Gallium is finally determined by precipitation with cupferron and ignition to the oxide, or for trace amounts of gallium, by colorimetric determination with rhodamine B. The method was checked with radioactive gallium and iron.     

The Role Played by Ga-Pt Nanoparticles in the Aromatization of Lower Alkanes on ZSM-5 Zeolites

The activity and selectivity of Pt-Ga/ZSM-5 zeolites in the aromatization of ethane was studied. The temperature intervals of the stability of gallium oxides on the surface of zeolites were determined by X-ray diffraction. The formation of GaPt clusters was observed after high-temperature treatment of a mixture of platinum-containing zeolites with gallium oxides. Density functional theory was used to study the state of gallium clusters in zeolites by quantum-chemical methods. The interaction of gallium with the H-form of ZSM-5 zeolites was shown to result in the formation of cationic centers containing reduced single-charged gallium cations. The introduction of platinum stabilized alloyed Ga-Pt particles localized in zeolite channels. These particles increase catalyst activity in the aromatization of lower alkanes.     

Flame atomic absorption spectrometric determination of lead in waste water and effluent after preconcentration using a rapid coprecipitation technique with gallium phosphate

A determination method for lead in waste water and effluent was studied using flame atomic absorption spectrometry after preconcentration of lead by the rapid coprecipitation technique with gallium phosphate. Lead ranging from 0.5 to 50 microg was quantitatively coprecipitated with gallium phosphate from 100-150 mL sample solution (pH approximately 5). The presence of gallium phosphate did not affect the atomic absorbance of lead. Since the concentration of gallium in the final sample solution is also measurable by flame atomic absorption spectrometry at 250.0 nm without further dilution, the rapid coprecipitation technique, which does not require complete collection of the precipitate, becomes possible using a known amount of gallium and measuring the concentrations of both lead and gallium in the final sample solution by flame atomic absorption spectrometry. The 32 diverse ions tested gave no significant interferences in the lead determination. The method proposed here is rapid and has good reproducibility.     

Preconcentration of gallium by coprecipitation with synthetic zeolites prior to determination by electrothermal atomic absorption spectrometry.

Synthetic zeolites were dissolved in nitric acid, and the resulting solution used as a coprecipitant for the preconcentration of trace amounts of gallium in water samples prior to determination by electrothermal atomic absorption spectrometry (ETAAS). The gallium preconcentration conditions and the ETAAS measurement conditions were optimized. Gallium was quantitatively concentrated with the zeolites coprecipitate from pH 6.0 to 8.0. The coprecipitate was easily dissolved in nitric acid, and an aliquot of the resulting solution was introduced directly into a tungsten metal furnace. The atomic absorbance of gallium in the resulting solution was measured by ETAAS. An ashing temperature of 400 degrees C and an atomizing temperature of 2600 degrees C were selected. The calibration curve was linear up to 3.0 microg of gallium and passed through the origin. The detection limit (S/N > or = 3) for gallium was 0.08 microg/100 cm3. The relative standard deviation at 1.0 microg/100 cm3 was 3.0% (n = 5). The proposed method has been successfully applied to trace gallium analysis in environmental water samples.     

卤代苯溶剂对镓咔咯配合物光物理性质的影响:外重原子效应

利用紫外-可见光谱、稳态和时间分辨荧光光谱以及飞秒瞬态吸收光谱探测了不同卤代苯溶剂对三种五氟苯基取代的镓咔咯(1-Ga、2-Ga、3-Ga)光物理性质的影响,结果表明卤代苯溶剂的色散力对于镓咔咯电子光谱吸收峰位置的影响起着主要作用;溶剂外重原子效应能显著降低镓咔咯的荧光量子产率。飞秒瞬态吸收光谱表明,光激发下,镓咔咯与卤代苯溶剂之间可发生电子转移反应,溶剂的重原子效应可以减缓电荷分离态复合物电荷重组速率。     

Determination of gallium by square-wave voltammetry anodic stripping, based on the electrocatalytic action of 2,2'-bipyridine in dimethylsulphoxide: comparison with an aqueous NaSCN/NaClO(4) electrolyte

Deposition potential, deposition time, square-wave frequency, 2,2'-bipyridine concentration, and gallium concentration have been studied in detail, for the determination of trace concentration levels of the metal by square-wave voltammetry anodic stripping analysis, in dimethylsulphoxide. Optimum conditions have been found for gallium(III) determination and results compared to those obtained in 0.5M NaSCN + 4.2M NaClO(4) aqueous electrolyte by obtaining calibration graphs for the range 1 x 10(-8)M-1 x 10(-5)M gallium. Accuracy (+/- 3%) and precision (4-6% SD) of this method were assessed with both 4 x 10(-8)M and 4 x 10(-7)M gallium solutions used as synthetic samples. The efficiency of solvent extraction of gallium with di-isopropyl ether was found to be 99.98% at a 4 x 10(-7)M gallium concentration. The proposed method was applied to the determination of the gallium content in rock mineral samples (using the above mentioned solvent extraction procedure), are compared to those obtained with the NaSCNNaClO(4) based electrolyte. No statistically significant difference was observed. Analytical procedures followed are given in detail.     

Effect of gallium nitrate on the in vivo distribution of 67Ga in rats bearing inflammatory lesions

Effect of gallium nitrate on the pharmacokinetics and tissue accumulation of 67Ga was investigated in rats bearing turpentine oil-induced abscess. Gallium nitrate accelerated the blood disappearance of 67Ga, but this effect was less potent than that of ferric nitrate. The accumulation of 67Ga in liver was significantly lowered by gallium nitrate, but no significant decrease of 67Ga accumulation in abscess was observed. On the other hand, 67Ga accumulation in bone was slightly facilitated by gallium nitrate. Ferric nitrate exerted a similar effect on tissue accumulation of 67Ga as gallium nitrate.     

Flame atomic absorption spectrometric determination of lead in waste water and effluent after preconcentration using a rapid coprecipitation technique with gallium phosphate

A determination method for lead in waste water and effluent was studied using flame atomic absorption spectrometry after preconcentration of lead by the rapid coprecipitation technique with gallium phosphate. Lead ranging from 0.5 to 50 μg was quantitatively coprecipitated with gallium phosphate from 100–150 mL sample solution (pH ∼5). The presence of gallium phosphate did not affect the atomic absorbance of lead. Since the concentration of gallium in the final sample solution is also measurable by flame atomic absorption spectrometry at 250.0 nm without further dilution, the rapid coprecipitation technique, which does not require complete collection of the precipitate, becomes possible using a known amount of gallium and measuring the concentrations of both lead and gallium in the final sample solution by flame atomic absorption spectrometry. The 32 diverse ions tested gave no significant interferences in the lead determination. The method proposed here is rapid and has good reproducibility. Received: 16 August 1999 / Revised: 6 October 1999 / Accepted: 14 October 1999     

Triethylborane-induced radical reactions with gallium hydride reagent HGaCl2

[see reaction]. A gallium hydride reagent, HGaCl2, was found to act as a radical mediator, like tributyltin hydride. Treatment of alkyl halides with the gallium hydride reagent, generated from gallium trichloride and sodium bis(2-methoxyethoxy)aluminum hydride, provided the corresponding reduced products in excellent yields. Radical cyclization of halo acetals was also successful with not only the stoichiometric gallium reagent but also a catalytic amount of gallium trichloride combined with stoichiometric aluminum hydride as a hydride source.     

A PVC-membrane bulk optode for gallium(III) ion determination

An optical probe responsive to gallium(III) ion has been developed. The gallium sensing system was prepared by incorporating 4-(p-nitrophenyl azo)-pyrocatechol (NAP) as ionophore in a plasticized PVC membrane containing tributylphosphate (TBP) as plasticizer. The sensing membrane in contact with gallium ion at pH 3.5, changes color from yellow-brown to pink-brown. Under optimum conditions, the proposed membrane displayed a linear range of 5-83 μM with a limit of detection of 4 μM. The response time of the membrane was within 10-15 min depending on the concentration of Ga³⁺ ions. The selectivity of the probe towards gallium determination was found to be very good. Experimental results showed that the probe could be used as an effective tool in analyzing the gallium content of water samples.     

Determination of gallium in biological fluids using inductively coupled plasma mass spectrometry

A procedure for the determination of gallium in biological fluids by inductively coupled plasma mass spectrometry was developed. The detection limits of gallium calculated from the 3s value were 60 ng/L for urine, 32 ng/L for a model solution of intestinal juice, and 50 ng/L for serum. The accuracy of the procedure was tested using a standard addition method. The nature of a background signal on the masses of gallium isotopes was studied with the use of a high-resolution mass spectrometer, and the background concentration of gallium in biological fluids was evaluated (5–7 ng/L). It was found that a background level in measurements performed on a quadrupole mass spectrometer depends on the interfering influence of polyatomic ions with close m/z ratios rather than on the background concentration of gallium. The procedure makes it possible to study the stability of pharmaceutical preparations based on gallium in biological media, their metabolism, and the excretion of preparations from the body.     

Extraction-photometric determination of gallium with phenylfuorone in alkaline carbonate solutions in the presence of polyethylene glycol

The main regularities in the extraction of gallium from alkaline carbonate solutions with phenylfluorone in the system polyethylene glycol (PEG)-sodium carbonate-water were studied by spectrophotometry and inductively coupled plasma mass spectrometry. It was demonstrated that, under these conditions, the distribution coefficient of gallium is above 100 and the recovery is ～98% (at the ratio of phases PEG: salt = 1: 2). The ratio between gallium and the reagent in the complex was determined, and the structure of the coordination sphere of the central atom in the extracted complex was proposed. It was demonstrated that gallium can be determined by the extraction-photometric method at pH 11–14 in the presence of a fivefold amount of aluminum.     

Purification of gallium from bismuth and polonium by melting under synthetic slags

A method for the purification of technical grade gallium from bismuth and polonium by melting under synthetic slags is proposed. The examination of the purification degrees of gallium from bismuth and polonium was carried out with the aid of radioactive tracers²¹⁰Bi and²¹⁰Po. In order to obtain a gallium-bismuth alloy a suitable apparatus was assembled. The conditions of melting were established. The optimum conditions for the purification of gallium were established and the purification degrees of gallium from bismuth and polonium were determined.     

Gal3 Catalyzed Tetrahydropyranylation of Alcohols and Phenols

In dichloromethane, the nucleophilic addition of alcohols or phenols to 3,4-dihydro-2H-pyran (DHP) was catalyzed effectively by gallium triiodide which was generated in situ by the reaction of gallium metal and iodine to give the corresponding tetrahydropyranyl acetals in good to excellent yields.     

Spectral interferences and background overcompensation in zeeman-corrected atomic absorption spectrometry : Part 1. The effect of iron on 30 elements and 49 element lines

The background compensation performance of a Zeeman corrector with the magnetic field acting on the graphite atomization cell was assessed for 30 elements and 49 element lines in an iron matrix. Two of the elements studied, gallium and zinc, are influenced by background overcompensation which introduces serious negative systematic errors. The overcompensation is due to the presence of iron lines close to the 287.4-nm gallium line and the 213.9-nm zinc line; when the magnetic field is on, the σ-components of the adjacent iron lines overlap at the position of the analyte line and a background, which is not present when the magnetic field is off, is recorded. When gallium and zinc are measured under the same conditions but with deuterium arc background correction, the adjacent iron lines cause positive systematic errors. These spectral interferences for gallium in the presence of iron can be avoided by doing the measurements at the 294.4-nm gallium line; the two lines have about the same sensitivity. When zinc is to be measured at the 213.9-nm line, with either type of background correction, the spectral interferences from iron can be avoided by careful selection of the graphite-furnace parameters. In addition to spectral interferences, iron also affects the sensitivity for both gallium and zinc.     

Adsorption properties of oxidized gallium-modified zeolite ZSM-5 from diffuse reflectance IR and quantum-chemical data: 1. Interaction with hydrogen and ethane

Diffuse reflectance IR spectroscopy was used to study adsorption and subsequent high-temperature hydrogen and ethane transformations on gallium ions in gallium-modified ZSM-5 zeolite. The results were correlated with the corresponding quantum-chemical calculations. From the experimental and calculated data, it follows that trivalent gallium oxo ions are reduced to the univalent state in a hydrogen or ethane atmosphere even at moderate temperatures. Therefore, gallium oxo ions can function as active sites only at the early stages of light-paraffin aromatization. At the later stages, the dehydrogenation of light paraffins involves univalent gallium ions through the formation of intermediate gallium and alkylgallium hydrides.     

Photocatalytic Hydrogen and Oxygen Formation from Water over Ga-modified Zeolite

Water could be decomposed into hydrogen and oxygen over Ga-modified ZSM-5 zeolite under UV irradiation. The photocatalytic activity was elevated significantly by supporting the gallium species and was sensitive to the loading amount of gallium species on the ZSM-5 zeolites.     

衬钽管石墨炉原子吸收法测定痕量镓时基体改进剂的研究及应用

提出用钒和铜混合基体改进剂衬钽管石墨炉原子吸收测定镓的方法。衬钽管使镓的灵敏度提高6倍左右,钒和铜混合基体改进剂不仅能进一步提高灵敏度,而且能提高灰化温度,降低原子化温度,增强抗干扰能力。测定 GSD 标准样品中的镓时,不需对样品进行预分离即可直接进行测定,结果与参考值相符。     

Deuteron activation analysis of carbon in gallium arsenide using substoichiometric precipitation

Ultra trace carbon in gallium arsenide has been determined by deuteron activation analysis. It consists of steam distillation of nitrogen as ammonia and successive substoichiometric precipitation as ammonium tetraphenylborate. It is confirmed that nitrogen is precipitated substoichiometrically as ammonium tetraphenylborate in spite of the various chemical species of¹³N. The procedure developed was applied to the deuteron activation analysis of carbon in carbon-doped and undoped gallium arsenides. It took 30 minutes from the end of irradiation to the start of the radioactivity measurement. The detection limit of carbon in gallium arsenide was as low as 1 ppb.     

Bulk synthesis of single-crystalline magnesium oxide nanotubes

Crystalline tubular magnesium oxide nanostructures were obtained through carbon-thermal evaporation of a MgO powder. Gallium oxide was added into the mixture of MgO and carbon. The reduction of gallium oxide by carbon resulted in gallium vapor at high temperatures. Condensed gallium droplets catalyzed the anisotropic growth of tubular MgO nanostructures in situ. The products were characterized by X-ray powder diffraction technique, scanning electron microscopy, and high-resolution microscopy. All the analyses indicated that the prepared tubular MgO nanostructures are, in fact, single crystals.