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71.
An application of coupled column ion chromatography (IC)-inductively coupled plasma mass spectrometry (ICP-MS) is presented for speciation of chromium in waste waters. By coupling an anion column with a cation column, both the cationic Cr(III) and anionic Cr(VI) species can be analyzed with detection limits below 0.5 μg/1. The separation of the interfering ions (chloride, chlorate, perchlorate, sulphate, sulphite, sulphide, thiosulphate, carbonate, cyanide and some organic compounds) from the chromium peaks is discussed, and the use of different chromium isotopes for data acquisition is compared. Based on the results, m/z 52 was considered as an ideal isotope for speciation of chromium in waste waters by the coupled column IC-ICP-MS, because it did not suffer from polyatomic interferences and due to the high sensitivity for chromium. The analysis of the waste water samples should be performed as soon as possible after sampling according to the stability tests of the species. 相似文献
72.
稀土及其配合物对蛇毒磷脂酶A_2活性的影响 总被引:4,自引:0,他引:4
分别研究了三价稀土离子 (La3 + ,Eu3 + ,Dy3 + ,Yb3 + )、二乙三胺五乙酸及其衍生物二乙三胺五乙酸 -双二甲酰胺 ,二乙三胺五乙酸 -双 (异烟肼 )与稀土离子的配合物以及Tb -谷氨酰胺配合物对蛇毒磷脂酶A2 活性的影响 .浓度低于 <3μmol/L的稀土离子可以激活磷脂酶A2 ,浓度大于 5 μmol/L后稀土离子对酶活性表现出抑制作用 ;外源Ca2 + 离子的加入可以缓解稀土离子对酶活性的抑制作用 ,表明稀土离子和钙离子是竞争性地结合在酶的活性部位 ;稀土离子和二乙三胺五乙酸及其衍生物的配合物对酶活性没有明显影响 ;Tb -谷氨酰胺在浓度大于 10 μmol/L后开始抑制酶的活性 相似文献
73.
The asymmetric synthesis of the (+)-Kishi lactam and an intermediate for the preparation of the marine natural product fasicularin is reported. The keystone of this divergent synthesis is the diastereoselective azaspirocyclization of an N-methoxy γ-arylbutanoamide, which is believed to proceed through the intermediacy of an N-acylnitrenium ion. 相似文献
74.
75.
Y. Marcus 《Journal of solution chemistry》1994,23(7):831-848
The water-structural contributions to the entropies and heat capacities of hydration of over 120 ions and the viscosity B-coefficients of nearly 80 aqueous ions are tabulated and correlated. B-coefficients for many more ions are predicted from this relationship and from their dependence on ionic size and charge. The structural entropies determine a unique scale of water structure making and breaking by the ions. 相似文献
76.
R. Acevedo T. Meruane E. Cortés S. O. Vasquez C. D. Flint 《Theoretical chemistry accounts》1994,88(2):99-110
Summary A theoretical model to calculate the vibronic intensities induced by the odd vibrational modes in centrosymmetric lanthanide complexes is developed and applied to octahedral complex ions, LnX
6
3–
, such as occur in the hexachloroelpasolites Cs2NaLnCl6. Both the crystal field and the ligand polarisation contributions are evaluated using a standard set of symmetry coordinates. For the crystal field term a truncated expansion of the intermediates states is employed rather than the more conventional closure approximation. Special care is necessary to ensure that the phases of the contributions are correctly determined since the cross-term between the ligand polarisation and crystal field contributions is signed. General equations applicable to anyf
n
complex ion are derived and an example of their application to the PrCl
6
3–
ion is given The agreement with experiment is satisfactory. 相似文献
77.
A. V. Sinitsky M. B. Darhovskii A. L. Tchougreff I. A. Misurkin 《International journal of quantum chemistry》2002,88(4):370-379
In the present work the semiempirical effective crystal field (ECF) method previously designed for electronic structure calculations of transition metal complexes and utilizing non‐Hartree–Fock trial wave function and parameterized for complexes of doubly charged Cr2+, V2+, Mn2+, Fe2+, Co2+, and Ni2+ cations is extended to complexes of triply charged cations of 3d‐elements. With the parameters adjusted the ECF method is applied to calculations of ground states and low‐energy spectra of the d‐shells of fluoro‐, chloro‐, aqua‐, amino‐, and cyano‐complexes of the triply charged cations. Obtained total spin and symmetry of the ground states match the experimentally observed ones. Satisfactory agreement between the calculated and experimental d‐shell electronic transition energies is achieved as well. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 相似文献
78.
The design and synthesis of a porphyrin-appended terpyridine, 5-(4-([2,2′:6′,2″]-terpyridin-4-yl-carboxyamidyl)phenyl)-10,15,20-triphenylporphyrin (H2TPPTPy) and its application as potential fluoroionophore for recognition of metal ions are reported. For preparation of the fluoroionophore, a novel simple strategy with improved total yield has been applied for the synthesis of 2,2′:6′,2″-terpyridine-4′-carboxylic acid as a ligand. H2TPPTPy shows chelation-enhanced fluorescence effect with cadmium ion via the interruption of photoinduced electron transfer (PET) process, which has been utilized as the basis of the fabrication of the Cd(II)-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed Cd(II)-sensitive chemosensor were investigated. It shows a linear response toward Cd(II) in the concentration range of 3.2 × 10−6 to 3.2 × 10−4 M with a limit of detection of 1.2 × 10−6 M. The chemosensor shows good selectivity for Cd(II) over a large number of cations, such as alkali, alkali earth and transitional metal ions except Cu(II) and Zn(II). The sensor has been used for determination of Cd(II) in water samples with satisfactory recoveries. 相似文献
79.
The preliminary results described here show the complete transfer of Hg(II) ions, in the absence of a chelating agent in 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids; the lag time required to gain the quantitative metal ion partition turned out to be strongly dependent both on alkyl chain length on the imidazolium ring and on the working temperature. 相似文献
80.