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51.
The adaptation of a conventional atomic-absorption/flameemission spectrophotometer to the measurement of atomic-fluorescence in an air-acetylene flame is described. The determination of cadmium on the same instrument by both atomic-fluorescence and absorption shows that, even with a rather simple and inefficient means of exciting and measuring fluorescence, results can be obtained which indicate that the fluorescence technique is considerably more sensitive than atomic-absorbance and is equally free from inter-element interference. 相似文献
52.
A series of new RhIII complexes with N-substituted salicylaldimines have been prepared of the form [RhSBPy2]PF6 where SB is a tetradentate N,N′-substituted bis(salicylaldimine) or represents two molecules of a corresponding bidentate derivative. Several of these complexes have been reduced with 0.5% sodium amalgam and the products reacted with CH3I to yield the organometallic derivatives CH3RhSBPy. 相似文献
53.
A fluorimetric method for the determination of citrate is described. Through a series of reactions, citrate is converted into citrazinic acid. The ammonium salt of this compound exhibits a fluorescence maximum at 430 nm when an excitation source of 340 nm is used. The method does not suffer from the normal interferences. The limit of detection is 0.01 μg ml-, and the best working range is 0.1–10 μg ml-1. 相似文献
54.
55.
The application of a separated air-acetylene flame to the determination of several elements by long-path atomic-absorption spectroscopy is described. The factors which govern the stability and reproducibility of the separated flame have been investigated. High sensitivity and stability and low background absorption are obtained in the the determination of zinc, iron, copper, mercury, magnesium and silver by the method described. 相似文献
56.
Douglas X. West Robert D. Profilet John C. Severns Roger K. Bunting 《Transition Metal Chemistry》1988,13(1):29-34
Summary A series of cobalt(II), nickel(II) and copper(II) complexes of 2-picolinamineN-oxide, HA, has been prepared. Solids of formula [M(HA)3](BF4)2 (M=cobalt(II) or nickel(II); [Cu(HA)2]X2 (X=BF
4
–
, NO
3
–
); [Co(HA)2X2] (X=Cl– or Br–); [Ni(HA)2Cl2] and [Cu(HA)X2] (X=Cl– or Br–] have been isolated and characterized by partial elemental analyses, molar conductivities, magnetic susceptibilities, DSC-TGA, and spectral methods. All complexes were found to be monomeric, and their spectral parameters are compared with those of the metal ion complexes ofN-alkyl-2-picolinamineN-oxides, 2-dialkylaminopyridineN-oxides and 2-picolinamine. The cobalt(II) and nickel(II) halide complexes spectrally show a mixture of octahedral and tetrahedral centres. 相似文献
57.
Summary The chlorides and bromides of cobalt(II), nickel(II) and copper(II) along with the acetates of the latter two metal ions and copper(II) tetrafluoroborate were used to prepare complexes ofN-2-(5-picolyl)-N-phenylthiourea (5MTUH). 5MTUH coordinates as a bidentate ligand via the pyridyl nitrogen and the sulphur atoms in the cobalt(II) complexes and the compounds isolated with Cu(BF4)2 and CuCl2. Complexes of stoichiometry [Cu(5MTU)X] (X=Br or C2H3O2) appear to have the deprotonated ligand coordinated via the pyridyl andN thioamide nitrogens and the sulphur atom. The nickel(II) complexes involve monodentate 5MTUH with sulphur being the donor atom. A violet, octahedral [Co(5MTUH)2Cl2] complex and a blue, tetrahedral [Co(5MTUH)Cl2] complex have been isolated, but with CoBr2 only an octahedral complex could be prepared. 相似文献
58.
An atmospheric pressure microwave-excited emissive argon plasma is evaluated for use as a detector in conventional gas-chromatographic analysis. A range of carbon-, oxygen-, nitrogen- and halogen-containing compounds was investigated in order to optimize the sensitivity, linear working range and plasma operating conditions. For the non-selective determination of carbon-containing compounds, the atomic carbon emission at 247.9 nm was found to be most useful. At this wavelength the sensitivities for all the compounds investigated were directly proportional to the amount of carbon in the compounds. The limit of detection for these compounds at 247.9 nm was 1.94·10-l0 g of carbon per sec. The atomic lines at 206.2 nm (I) and 470.5 nm (Br) were the best for the selective determination of iodine- and bromine-containing compounds respectively, and a new band emission at 256 nm, characteristic of chlorinecontaining compounds, gave good sensitivity. 相似文献
59.
Douglas B. West 《Studies in Applied Mathematics》1978,59(3):245-248
Consider the question: When can the edges in a pair of Hamiltonian circuits be redistributed to form another pair of circuits with the same union and intersection? A class of pairs is exhibited which intersect in two edges and cannot be rearranged in this way. A connection to algorithms for the traveling salesman problem is explained using the convex polytope of Hamiltonian circuits in . The exhibited pair is shown to be an edge of that polytope. 相似文献
60.
A study has been made of the comparative suitability of the ceriumIII, lanthanum and praseodymium chelates of alizarin complexan as reagents for the spectrophotometric determination of microgram amounts of fluoride. The ceriumIII reagent is most sensitive at pH < 4.5 and the lanthanum reagent at pH 5.0. An enhancement of sensitivity may be obtained for both reagents at pH 4.3 by addition of acetone to 25 % v/v, but the most sensitive means of determination is to use the lanthanum reagent in aqueous solution at pH 5.2 with measurement at 281 mμ. This procedure is 200% more sensitive than the standard method at 620 mμ. 相似文献