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81.
共价氢化物与汞离子反应的研究:Ⅱ.痕量硒的高灵敏分析新方法 总被引:4,自引:0,他引:4
本文详细研究了硒化氢与汞离子反应条件并建立了氢化物发生-冷原子荧光法间接测定痕量硒的新方法。考察了各种实验条件,并将此方法用于合成水样分析,得到一些有意义的结果。 相似文献
82.
Marilyn Daisy Milton Sarbjot Singh Sokhi Monika Maheshwari Minakshi Asnani 《Tetrahedron letters》2004,45(48):8941-8944
A novel class of multifunctional and multinucleate chalcogen (selenium and tellurium) containing derivatives (1-10) has been developed based on sequential chloride substitution of 2,4,6-trichloro-1,3,5-triazine with chalcogen-bearing amines. The structure of compound 1 has been determined in the solid state by X-ray crystallography. 相似文献
83.
A study of the interactions of several selenium species with living bacterial cells was carried out by Fourier-transform infrared (FT-IR) spectroscopy. Bacterial cells consisted of an Escherichia coli strain (K-12) cultivated in a growth medium based on glucose contaminated with selenium species. Equilibrium between the analyte in the solution and the extraction medium was established, and then the effects of selenium species upon the external membrane of the living bacterial cells were characterized by performing FT-IR spectroscopy of whole cells. The presence of the toxicants at various concentrations in the culture medium had an effect on the FT-IR spectra, and the concentration of the selenium species was determined directly in the biomass by FT-IR spectroscopy. The intensity ratios between several absorption lines, which varied as a function of the concentration of the selenium species, were used as the analytical signal.Electronic Supplementary Material Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material. 相似文献
84.
An efficient route to a 5,6-dihydropyrano[3,4-b]pyridin-8-one core in two steps from enaminolactones
Cheikh Sall Sandrine Paquelet Jean Michel Chezal Yves Blache 《Tetrahedron letters》2008,49(8):1301-1304
A convenient two step conversion of heterocyclic enaminolactones to heterocyclic fused 2-pyran-1-ones is reported. The use of this method can be applied to a wide variety of aromatic and heteroaromatic amines to give potentially biologically active compounds in good yields. 相似文献
85.
电感耦合等离子体原子发射光谱法测定电解金属锰中硒、铁、硅 总被引:1,自引:0,他引:1
本文采用稀硫酸溶解试样,ICP-AES法同时测定电解金属锰中硒、铁、硅,通过对溶样酸、锰基体以及背景的研究,确定了分析条件。该方法简便具有良好的精密度和准确性,相对标准偏差不大于2.68%,回收率为98%-105%。经t检验与经典法无显著性差异。 相似文献
86.
The first synthesis of 1,3-oxaselenepane derivatives by the reaction of aryl isoselenocyanates with 4-bromobutanol in the presence of sodium hydride in THF as a one-pot reaction is described. The Z/E isomerism for the exocyclic carbon-nitrogen double bond in the selenium heterocycles was observed for the first time. 相似文献
87.
C.V.S. Ieggli D. Bohrer S. Noremberg P.C. do Nascimento L.M. de Carvalho S.L. Vieira R.N. Reis 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009
An oil-in-water formulation has been optimized to determine trace levels of selenium in whole hen eggs by graphite furnace atomic absorption spectrometry. This method is simpler and requires fewer reagents when compared with other sample pre-treatment procedures. Graphite furnace atomic absorption spectrometric (GF AAS) measurement was carried out using standard addition calibration and Pd as a modifier. The precision, expressed as relative standard deviation, was better than 5% and the limit of detection was 1 µg L− 1. The validation of the method was performed against a standard reference material Whole Egg Powder (RM 8415), and the measured Se corresponded to 95.2% of the certified value. The method was used for the determination of the Se level in eggs from hens treated with Se dietary supplements. Inorganic and organic Se sources were added to hen feed. The Se content of eggs was higher when hens were fed with organic Se compared to the other treatments. The proposed method, including sample emulsification for subsequent Se determination by GF AAS has proved to be sensitive, reproducible, simple and economical. 相似文献
88.
Aino J. Karhu Juho Jämsä J. Mikko Rautiainen Raija Oilunkaniemi Tristram Chivers Risto S. Laitinen 《无机化学与普通化学杂志》2017,643(7):495-500
The reaction of tBuNH2 with a mixture of SeCl2 and SeOCl2 in a 6:2:1 molar ratio produces the novel selenium‐nitrogen chain ClSeN(tBu)Se(O)Cl ( 4 ), in which the selenium atoms are in two different oxidation states, SeII and SeIV. The crystal structure of 4 is compared with that of the related SeII/SeII system ClSeN(tBu)SeCl ( 1 ) and differences are attributed to hyperconjugative effects. The energetics of the formation of 4 via two different routes are elucidated by PBE0/def2‐TZVPP calculations. 相似文献
89.
Christina M. Gonzalez Jeffrey Hernandez Jason G. Parsons Jorge L. Gardea-Torresdey 《Microchemical Journal》2010,96(2):324-329
Selenium (Se) is naturally occurring in the environment and is an essential nutrient in mammals. However, environmental Se can be increased to toxic levels through different industrial practices. The potential adsorption of the Se oxoanions, selenite and selenate, from aqueous solutions onto nanosynthesized MnFe2O4 was investigated using batch techniques and DRC-ICP-MS spectroscopy. The nanomaterial (NM) was laboratory synthesized through slow titration of a mixture of Fe2+ and Mn2+ ions. X-ray diffraction and Scherrer's equation were used to determine the phase of the material and crystallite size, respectively. The effects of pH, reaction time, competitive anions, and the adsorption capacity of the synthesized NM to bind selenite and selenate were investigated. The Langmuir isotherm was used to determine the binding capacity of the NM. Results showed that the phase of the nanomaterial was similar to Jacobsite with a size of 27.5 nm. Results also showed that the sorption of either 100 ppb of selenite or selenate was pH independent in the pH range 2 to 6 and occurred within 5 min of contact time. The introduction of Cl− and NO3− anions individually added to solution had no significant effect on the sorption of either selenite or selenate. However, it was found that the addition of SO42− had a competitive effect only on the sorption of selenate, first seen at 10 ppm and more pronounced at 100 ppm of SO42−. In the presence of 100 ppm of PO43−, the adsorption of selenate decreased to 87% while selenite sorption decreased to 20%. From the Langmuir isotherm equation it was determined that the nano-Jacobsite had a selenite and selenate binding capacity of 6573.76 and 769.23 mg Se/kg of NM, respectively. 相似文献
90.
Karl O. Christe David A. Dixon Mathias Hopfinger Thomas M. Klapötke Burkhard Krumm 《Journal of fluorine chemistry》2010,131(7):791-422
The [((C6H5)3P)2N]+, [(C6H5)4P]+ and [N(CH3)4]+ salts of SeF5−, SeF62− and SeOF3− and CsSeO2F were prepared and characterized. Crystal structures were obtained for [((C6H5)3P)2N][SeF5] and [((C6H5)3P)2N][SeOF3] CH2Cl2. In contrast to oxygen-bridged dimeric TeOF3−, the SeOF3− anion in [((C6H5)3P)2N][SeOF3] CH2Cl2 is monomeric and represents the first experimentally well determined molecular structure of a monomeric trifluoro-chalcogenite anion. Similarly, [((C6H5)3P)2N][SeF5] represents the first example of a structure containing a well-isolated undistorted SeF5− anion. The NMR and the vibrational spectra and their assignments were re-examined and corrected by comparison with high-level theoretical calculations. Whereas the previously published normal coordinate analysis of SeF5− is correct, that for SeOF3− needs major revision. 相似文献