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1.
Iron(II) (1.0 × 10?9–1.0 × 10?6 M) is determined by the production of chemiluminescence in a luminol system in the absence of added oxidant. Iron(III) (2.0 × 10.8?8–2.0 × 10?6 M) is determined after reduction to iron(II) in a silver reductor mini-column in the flow system. Cobalt, chromium, copper and manganese interfere. 相似文献
2.
Summary The synthesis and characterization of new iron(III) and copper(II) complexes of substituted phenylazo-2,4-dinitrosoresorcinol complexes are described. The iron complexes are of octahedral geometry (high-spin and low-spin states). The electronic transitions and the ligand field parameters (B, and ) are assigned and calculated. Two series of copper complexes were prepared, mononuclear and dinuclear, with distorted tetrahedral and square planar configurations, respectively. The adducts of the complexes with pyridine have square pyramidal structures. Complex formation takes placevia the azo-group and the phenolic oxygen atom in most cases. 相似文献
3.
Morgan Stefansson 《Journal of chromatography. A》1993,630(1-2):123-128
At high pH, saccharides become negatively charged by deprotonation of one or several hydroxylic groups and they are highly and selectively retained by ligand-exchange chromatography. The systems consist of a sulphonated polystyrene strong cation exchanger in europium(III) or iron(III) form and sodium hydroxide as mobile phase. The degree of complex formation is dependent on solute character and concentration, metal ion and pH, the reaction being of second order as confirmed by breakthrough studies. Rapid desorption of the solutes is performed by the introduction of an acidic mobile phase. Monosaccharides, and especially sugar alcohols, are selectively retained by a column in Fe(III) form whereas all saccharides are strongly retained as Eu(III) complexes, e.g., the capacity factor for the breakthrough of 10 μM glucose, in 0.1 M NaOH as mobile phase, was ca. 3500 The systems are proposed to be highly selective for the analysis of sugars. 相似文献
4.
A. M. Gaydukova V. A. Brodskiy V. V. Volkova V. A. Kolesnikov 《Russian Journal of Applied Chemistry》2017,90(8):1252-1257
Possibility of the electroflotation separation and extraction of cerium(II, IV), copper(II), and iron(II, III) from aqueous solutions is demonstrated. The optimal pH value and the concentration ratio of ions of the metals being separated, at which their electroflotation separation and extraction from aqueous solutions is the most efficient, was determined. It was shown that the electroflotation method is promising for selective separation and extraction of metal ions with various hydrate-formation pH values from aqueous solutions. 相似文献
5.
Piero Mirti 《Analytica chimica acta》1974,69(1):69-77
N-Carboxymelhyl pyrrolidine-2-carboxylic acid (CMPCA) is suggested as an optically active titrant. The values of the acidity constants of the ligand were determined and the order of magnitude of the stability constants of the complexes formed by CMPCA with some metal ions was evaluated. In order to determine the best conditions for the spectropolarimetric titrations, the dependence of the molar rotation of CMPCA and its complexes on wavelength and pH was examined. The spectropolarimetric titrations ofcopper(II), nickel(II) and iron(III) ions were carried out successfully. 相似文献
6.
Solid complex compounds of Fe(II) and Fe(III) ions with rutin were obtained. On the basis of the elementary analysis and thermogravimetric
investigation, the following composition of the compounds was determined: (1) FeOH(C27H29O16)·5H2O, (2) Fe2OH(C27H27O16)·9H2O, (3) Fe(OH)2(C27H29O16)·8H2O, (4) [Fe6(OH)2(4H2O)(C15H7O12)SO4]·10H2O. The coordination site in a rutin molecule was established on the basis of spectroscopic data (UV–Vis and IR). It was supposed
that rutin was bound to the iron ions via 4C=O and 5C—oxygen in the case of (1) and (3). Groups 5C–OH and 4C=O as well as 3′C–OH and 4′C–OH of the ligand participate in binding metals ions in the case of (2). At an excess of iron(III) ions with regard to rutin under the synthesis conditions of (4), a side reaction of ligand oxidation occurs. In this compound, the ligands’ role plays a quinone which arose after rutin
oxidation and the substitution of Fe(II) and Fe(III) ions takes place in 4C=O, 5C–OH as well as 4′C–OH, 3′C–OH ligands groups.
The magnetic measurements indicated that (1) and (3) are high-spin complexes. 相似文献
7.
A spectrophotometric determination of iron as its iron (III)-EDTA-H2O2-NH3 complex is described; up to 10-fold amounts of metals that form EDTA complexes absorbing at the same wavelength do not interfere because hydrogen peroxide reacts with thciron(IIl)-EDTA complex but does not affect the EDTA complexes of coppcr(II), nickel(II), cobalt(ltl) and chromium(Ilt). 相似文献
8.
《Journal of Coordination Chemistry》2012,65(17):2869-2874
Nanoparticles of a Bi(III) coordination polymer, {[Bi(μ-4,4′-bipy)Br4] · (4,4′-Hbipy)} n (1) (4,4′-bipy = 4,4′-bipyridine), were synthesized by a sonochemical method. The new nanoparticles were characterized by scanning electron microscopy, X-ray powder diffraction (XRD), IR spectroscopy, and elemental analyses. Compound 1 was structurally characterized by single-crystal X-ray diffraction. The thermal stabilities of 1 as bulk and at nanosize were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The Bi2O3 and BiBr3 nanostructures were obtained by calcinations of nanostructure of 1 in air and argon. 相似文献
9.
Rochut S Roithová J Schröder D Novara FR Schwarz H 《Journal of the American Society for Mass Spectrometry》2008,19(1):121-125
Electrospray ionization (ESI) of dilute solutions of 1,1'-bi-2-naphthol (BINOL) and iron(II) or iron(III) sulfate in methanol/water allows the generation of monocationic complexes of iron and deprotonated BINOL ligands with additional methanol molecules in the coordination sphere, and the types of complexes formed can be controlled by the valence of the iron precursors used in ESI. Thus, iron(II) sulfate leads to [(BINOLate)Fe(CH3OH)n]+ complexes (n=0-3), whereas usage of iron(III) sulfate allows the generation of [(BINOLdiate)-Fe(CH3OH)n]+ cations (n=0-2); here, BINOLate and BINOLdiate stand for singly and doubly deprotonated BINOL, respectively. Upon collision-induced dissociation, the mass-selected ions with n>0 first lose the methanol ligands and then undergo characteristic fragmentations. Bare [(BINOLdiate)Fe]+, a formal iron(III) species, undergoes decarbonylation, which is known as a typical fragmentation of ionized phenols and phenolates either as free species or as the corresponding metal complexes. The bare [(BINOLate)Fe]+ cation, on the other hand, preferentially loses neutral FeOH to afford an organic C20H12O+* cation radical, which most likely corresponds to ionized 1,1'-dinaphthofurane. 相似文献
10.
The syn-isomer of 1,8-bis(4,4′-diisopropyl-9,9′-diacridyl)naphthalene, 1, has been prepared by two consecutive Pd(PPh3)4-catalyzed Stille cross-coupling steps. This highly congested sensor undergoes Fe(III)-selective fluorescence quenching in water/acetonitrile even in the presence of excess of other metal ions. 相似文献
11.
A flow injection procedure for the sequential spectrophotometric determination of iron(II) and iron(III) in pharmaceutical products is described. The method is based on the catalytic effect of iron(II) on the oxidation of iodide by bromate at pH = 4.0. The reaction was monitored spectrophotometrically by measuring the absorbance of produced triiodide ion at 352 nm. The activating effect for the catalysis of iron(II) was extremely exhibited in the presence of oxalate ions, while oxalate acted as a masking agent for iron(III). The iron(III) in a sample solution could be determined by passing through a Cd-Hg reductor column introduced in the FIA system to reduce iron(III) to iron(II), which allows total iron determination. Under the optimum conditions, iron(II) and iron(III) could be determined over the range of 0.05 - 5.0 and 0.10 - 5.0 microg ml(-1), respectively with a sampling rate of 17 +/- 5 h(-1). The experimental limits of detection were 0.03 and 0.04 microg ml(-1) for iron(II) and iron(III), respectively. The proposed method was successfully applied to the speciation of iron in pharmaceutical products. 相似文献
12.
13.
The stability constants of the iron(II) complexes of TTHA (triethylenetetraminehexaacetic acid) were calculated from measured pH and redox potentials. The values of the cumulative constants obtained were: log βFeL= 15.37, log βFeHL = 23.83, log βFeH2L = 28.0, log βFe2L = 24.73. On the basis of these values and the previously determined constants ofiron(III) complexes, the possibilities of titrating iron(III) and iron(II) with TTHA were investigated. Depending on the experimental conditions, either FeL or Fe2L formed. Actual titrations were in agreement with the developed theory. The influence of aluminium and titanium on titrations of iron(III) solutions was elucidated. 相似文献
14.
The iron(II) and iron(III) complexes with EDTA can be determined separately and in mixtures in acetate-buffered medium at pH 4.0. The Evalues are in the range ?0.105 to ?0.112 V vs. SCE. Linear calibration plots are obtained over the range 0–1.0 mM for each oxidation state. A sample-handling procedure for avoiding oxidation of iron(II) species is described. It is shown that the acetate buffer system does not affect the stability of the iron-EDTA complexes. 相似文献
15.
Flow injection analysis can be used for the determination of both iron(II) and iron(III) with an amperometric detector. The flow-through cell contains a glassy carbon electrode. Selection of the appropriate voltammetric technique, choice of the indication potentials, sample size, composition of the carrier stream, etc., are discussed. The limit of determination is about 10-6 M; the calibration curves are linear in the concentration ranges 10-3–10-5 M for iron(III) and 5 × 10-4–10-5 M for iron(II). To illustrate the potentialities of the proposed method, standard rocks have been analysed. 相似文献
16.
Nano-particles of a new Bi(III) supramolecular compound, {Bi2(μ-4,4′-bipy)Cl10] · 2(4,4′-Hbipy) · (4,4′-H2bipy) · 2H2O} (1) {4,4′-bipy = 4,4′-bipyridine}, were synthesized by a sonochemical method. The nano-material was characterized by scanning electron microscopy, X-ray powder diffraction (XRD), IR spectroscopy and elemental analyses. Crystal structure of compound 1 was determined by X-ray crystallography. Calcination of the nano-particles of compound 1 at 400 °C under air atmospheres yields nano-sized particles of α-Bi2O3. 相似文献
17.
An analysis is made of earlier work by the authors in investigating the catalytic activity of Fe(III) and Cu(II) ions in solution and on different surfaces in certain redox reactions: the decomposition of H2O2, oxidation of ascorbic acid, etc. General principles have been established which provide a means of predicting one or another action of sorption on the catalytic activity: if the reaction proceeds within the ion exchanger phase as in a homogeneous (concentrated) solution, it is most probable to have a decrease (or cessation) of the catalytic activities of the ions. If the ion catalysts are included in a surface complex in whose coordination sphere there are places which the substrate may occupy the reaction is facilitated. The analysis carried out of the influence of sorption on the catalytic activity of the iron and copper ions shows a favorable change in the catalytic activity for these ions during their sorption on different types of surfaces.Translated from Teoreticheskie i Éksperimental'naya Khimiya, Vol. 22, No. 6, pp. 706–711, November–December, 1986. 相似文献
18.
Trans-1,2-cyclohexanediaminetetra-acetic acid (DCTA) chelates of bismuth(III), iron(III) and copper(II) have been separated by two techniques using reversed-phase paired-ion chromatography. In one, the chelates in aqueous solution were separated within 20 min on a 6.0 × 300 mm ERC-ODS column with 10−2M tetrabutylammonium ion (TBA+) in methanoi-water mixture (45:55 v/v) as eluent. In the other, the metal ions in aqueous solution were separated within 10 min by direct injection into an ERC-ODS column with 10−2M TBA+/10−3M DCTA in methanoi-water mixture (40:60 v/v) as eluent. 相似文献
19.