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171.
The present work describes a selective, rapid and economical method for the determination of cobalt using the 2-(2-benzothiazolylazo)-p-cresol (BTAC) as a spectrophotometric reagent associated with a solid extraction on polyurethane foam. The BTAC reacts with Co(II) in the presence of Triton-X100 surfactant forming a green complex with maximum absorption at 615 nm. The reaction is used for cobalt determination within a pH range of 6.50-7.50, with an apparent molar absorptivity of 1.62 x 10(4) L mol(-1) cm(-1). Beer's Law is obeyed for a concentration of at least 1.60 microg ml(-1). A selective procedure is proposed for cobalt determination in the presence of Fe(II), Hg(II), Zn(II) and Cu(II) up to milligram levels using masking agents. Polyurethane foam is used for the preconcentration and separation of cobalt from thiocyanate media and this procedure is applied to its determination in nickel salts and steel alloys. 相似文献
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L. Fernandes C. Pagano Gonçalves da Silva 《Journal of Radioanalytical and Nuclear Chemistry》1993,172(2):313-318
The radiopharmaceutical201TlCl(thallium-201 chloride) is used in nuclear medicine for myocardial visualization. The solution of201TlCl was prepared using201Tl obtained by irradiating a natural mercury target with protons from the CV-28 cyclotron installed at IPEN-CNEN/SP. This solution was subjected to different quality control processes required for its use in medicine. Some of these controls concerned the determination of the radionuclidic impurities:200Tl,202Tl and203Hg; the chemical identification of201Tl+; the hydrazine concentration, mercury contamination and the presence of phosphate. Furthermore. the biological distribution in Wistar rats and tests for sterility, pyrogenicity and toxicity were carried out. It was verified that the solution obtained was in the form of thallous chloride. This radiopharmaceutical gave good heart images in animals but due to the high levels of200Tl and202Tl its use in humans is not possible unless enriched202Hg is used as target in the irradiation. 相似文献
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Sílvia S. P. R. Almeida Joo J. R. Fraústo Da Silva Armando J. L. Pombeiro 《Journal of organometallic chemistry》1993,450(1-2)
Treatment of a THF solution of trans-[ReCl(N2)(dppe)2] (dppe = Ph2PCH2CH2PPh2) with a 1-alkyne HCCR (R =tBu, CO2Me, CO2Et, or C6H4Me-4), in the presence of Tl[BF4]/[NH4][BF4], under sunlight, affords the corresponding carbyne-fluoro complexes trans-[ReF(CCH2R)(dppe)2][BF4] in an unprecedented single-pot synthesis. Further reaction with [BU4N]OH leads to the vinylidenefluoro compounds trans-[ReF(=C=CHR)(dppe)2] (R = CO2Me, CO2Et, or C6H4Me-4). 相似文献
178.
João P.C. Tomé Dong-Gyu Cho Maria G.P.M.S. Neves Artur M.S. Silva 《Tetrahedron letters》2006,47(18):3131-3134
Sapphyrins participate in Diels-Alder reactions with pentacene affording novel barrelene-fused sapphyrins. The new compounds were synthesized using traditional heating and microwave irradiation conditions. The experiments carried out under microwave irradiation proved cleaner, affording only the monoadduct and in higher yields. 相似文献
179.
The Kalman filter algorithm was used to process data obtained in the simultaneous determination of species following first- and second-order kinetics. The performance of the algorithm in the quantification of chemical components from simulated data was assessed, and the influence of various parameters involved was estimated. The algorithm was applied to the resolution of cysteine-ascorbic acid and glutathione-ascorbic acid mixtures where the ascorbic acid followed pseudo first-order kinetics and the amino acids second-order kinetics in the reaction with the copper(II)-neocuproine system. Some features of the determinations (namely, afforded concentration ratios, accuracy and precision) are discussed. 相似文献
180.
Ferreira KQ Cardoso LN Nikolaou S da Rocha ZN da Silva RS Tfouni E 《Inorganic chemistry》2005,44(16):5544-5546
The synthesis of cis-[Ru(II)(cyclen)(L)(x)](n+) (cyclen = 1,4,7,10-tetraazacyclododecane and L = 2,2'-bipyridine (bpy), phenanthroline (phen) or 4-cyanopyridinium (4-NCpyH(+))) is reported. The freshly prepared complexes are stable in aprotic solvents and cyclen undergoes oxidative dehydrogenation reaction at high pH. These compounds also present solvent dependent conformational isomerization. 相似文献