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71.
Dietmar Krämer Erwin Rosenberg Achim Krug Robert Kellner Wolfgang Hutter Werner Hampel 《Mikrochimica acta》1994,116(4):183-189
Chloride is determined indirectly by Spectrophotometric flow injection analysis. Two systems are compared, both based on the principle of ion exchange of easily detectable anions versus chloride from suitable mercury salts. The first method is based on the exchange of chloride with chloranilate which is detected at 332 nm or at 306 nm in neutral or in acidic medium respectively. In the second case, chloride reacts with Hg(SCN)2. The liberated thiocyanate forms a strongly coloured complex with Fe(III) in acidic solution with an absorption maximum at 460 nm. Both methods have a detection limit of about 5 mol Cl–/l (175 ng/ml). In the case of the thiocyanate method, the relative standard deviation is about 2% (7 measurements) in the range of 5 to 150 mol/l and decreases significantly to a value of approximately 0.2% at higher concentrations; for the chloranilate method it is 10% for lower and about 1% for higher concentrations respectively. 相似文献
72.
A Contribution on Ba3Pt4HgO11: The First Alkaline-Earth Oxoplatinate(II,V)/Oxomercurate Single crystals of Ba3Pt4HgO11 were prepared by oxygen high pressure technique (4 200–3 600 bar) and investigated by X-ray methods. It crystallizes with hexagonal symmetry, space group D? P6 2c, a = 6.021, c = 17.374 Å, Z = 2. Ba3Pt4HgO11 represents a new structure type, showing structural relationships to Ba2Hg3Pd7O14 and to the precious metal 6L-perovskites. The Hg2+ ions show dumb-bell like coordination, Pt2+ a square-planar surrounding and Pt5+ face shared double octahedra. 相似文献
73.
CdHgO2: An Oxomercurate related to the Crednerite Structure Single crystals of CdHgO2 were prepared by oxygen high pressure technique (600°C, 3900 bar) and investigated by X-ray technique. It crystallizes with monoclinic symmetry, space group C–C2/m; a = 5.933, b = 3.452, c = 5.875 Å, β = 91.26°; Z = 2. The Hg2+ ions show dumb-bell like coordination, Cd2+ an octahedral one. CdHgO2 shows strong relationship to the Crednerite structure. The orientation of the O? Hg? O dump-bells to the CdO6 octahedra layers is discussed with respect to related oxomercurates. 相似文献
74.
D. N. Kravtsov A. S. Peregudov L. S. Golovchenko E. I. Smyslova 《Russian Chemical Bulletin》1996,45(5):1194-1199
19F NMR spectroscopy was used to study the exchange reactions involving 4-fluorothiophenoxides, 4-nitrophenoxides, chlorides, and acetates of arylmercury and triphenylphosphinegold. The analysis of the data on equilibrium constants allows one to obtain information on the comparative chemical hardness of ArHg+ and Ph3PAu+ cations. The increase in the electron-donating ability of aryl ligands enhances the chemical hardness of ArHg+ cations, their influence being best described by 0 constants of substituted phenyl groups.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1255–1260, May, 1996. 相似文献
75.
A batch of sulphydryl cotton microcolumns was prepared and charged with a mixed Hg standard solution (methyl-, ethyl- and inorganic Hg, 10 g l–1 as Hg, 3 ml) and stored at 4 °C in a light-tight box. At regular time intervals over a 4 month period microcolumns were removed and Hg species were quantified by gas chromatography microwave-induced plasma atomic emission spectrometry (after elution, extraction and derivatization steps). It was found that analyte recoveries for methyl- and inorganic Hg were quantitative over the 4 month period while ethyl-Hg species appeared to be stable for up to 2 months. 相似文献
76.
Identification of selenium species in urine by ion-pairing HPLC–ICP–MS using laboratory-synthesized standards 总被引:1,自引:0,他引:1
Wrobel K Wrobel K Kannamkumarath SS Caruso JA 《Analytical and bioanalytical chemistry》2003,377(4):670-674
This study focused on the detection/identification of possible selenium metabolites in human urine. Organoselenium compounds not commercially unavailable were synthesized and characterized by electrospray mass spectrometry. Separation of selenomethionine, methylselenomethionine, trimethylselonium, selenoethionine, and selenoadenosylmethionine was achieved by ion-pairing HPLC with a mobile phase of 2 mmol L–1 hexanesulfonic acid, 0.4% acetic acid, 0.2% triethanolamine (pH 2.5), and 5% methanol. The column effluent was introduced on-line to inductively coupled plasma–mass spectrometry for selenium-specific detection (77Se and 78Se). For selenium speciation in urine, solid-phase extraction was carried out using C18 cartridges modified with hexanesulfonic acid. Selective retention of cationic species was observed from acidified urine (perchloric acid, pH 2.0). After elution with methanol, evaporation, and dissolution in the mobile phase, the sample was introduced to the HPLC–ICP–MS system and the chromatographic peaks were assigned by adding standards. The species identified in urine were selenomethionine, trimethylselonium ion, and selenoadenosylmethionine. The last species was detected for the first time and our results suggest that selenomethionine might enter the metabolic pathway of its sulfur analog in the activated methylation cycle.Kazimierz Wrobel and Katarzyna Wrobel are on the leave from the Institute of Scientific Research, University of Guanajuato, L. de Retana No. 5, 36000 Guanajuato, Gto., Mexico 相似文献
77.
An amperometric detector with a small thin mercury film electrode is described. The device demonstrates advantageous operational
characteristics such as small dispersion (D<2) and “memory effect” (me<0.6%), extensive maximum sample frequency (msf −200
samples/h), and high sensitivity. It has been proven useful in flow-injection analysis at a constant potential under hydrodynamic
conditions. 相似文献
78.
The interaction of ethidium bromide (2,7-diamino-10-ethyl-9-phenylphenanthridinium bromide; EB) with double stranded (ds) calf thymus DNA and thermally denatured single stranded (ss) DNA was studied in solution and at the electrode surface by means of transfer voltammetry using a carbon paste electrode (CPE) as working electrode in 0.2 M acetate buffer, pH 5.0. As a result of intercalation of this dye between the base pairs of dsDNA, the characteristic peak of dsDNA, due to the oxidation of guanine residues, decreased and after a particular concentration of EB a new peak at +0.81 V appeared, probably due to the formation of a complex between dsDNA and EB. The non-intercalated EB gives another peak, but at an increased concentration of the dye. A similar behaviour was observed during the interaction of the dye with ssDNA.Furthermore, the interaction of EB with ds, ss and supercoiled (sc) DNA was studied at the hanging mercury drop electrode (HMDE) surface by means of alternating current voltammetry in 0.3 M NaCl and 50 mM sodium phosphate buffer (pH 8.5) as supporting electrolyte. dsDNA yields a smaller peak at −1.42 V (peak III) compared to the one yielded by ssDNA, since the latter is a relaxed and more accessible form. By addition of EB into the buffer solution an increase of peak III was observed in the dsDNA form as well as in ssDNA resulting from their interaction with EB. Furthermore, the appearance of peak III in covalently closed circular scDNA after exposure to increasing concentrations of EB is a result of the introduction of ‘free ends’ in DNA affecting its structural integrity. 相似文献
79.
The rhodium-phosphine complex catalyst Rh(CO)(acac)(PPh3)(Ⅰ) for 1-hexene hydroformylation was studied under the following reaction conditions: CO/H2=1(mole rate), pressure 1.0 MPa, temperature 25-120℃, by using the pressurized in-situ 1H NMR technique. Experimental results indicated that the formation of a rhodium hydride complex from (Ⅰ) began at room temperature and its amount increased with increasing of reaction temperature. This intermediate complex began to decompose at 100℃ and disapeared completely at 120℃. The intensity change of the proton signal was parallel to catalytical activity in hydroformylation of olefins. Under pure CO pressure the proton signal of Ph-H bond was not observed. There was a 0.2 ppm difference in proton chemical shifts of Rh-H bond under pure H2 pressure and under H2+CO pressure. The results showed that the rhodium-hydride carbonyl complex is the active intermediate in the industrial hydroformylation process. 相似文献
80.
Square-wave voltammetry with the hanging drop mercury electrode as the working electrode was used for the determination of
ultratraces of explosives in aqueous solution. It was shown that the strong pressure dependence of the pneumatically controlled
multimode electrode system of a conventional Metrohm apparatus could be compensated by an additional pressure regulation,
through which the pressure variations could be decreased when switching from deaeration to the static measurements. By using
square-wave voltammetry with this electrode system after this modification the limits of detection for 2,4,6-trinitrotoluene
(TNT) and other TNT-metabolites could be decreased down to 0.2 μg L−1 when using a measurement time of 6 min. Also a simultaneous determination of TNT and hexahydro-1,3,5-trinitro-1,3,5-triazine
(RDX) was shown to be possible over a wide linear range and the detection limits then were 2.2 μg L−1 for TNT and 25 μg L−1 for RDX. By applying the highly stable and adjustable pressure as mentioned before, the calibrations could be kept stable
over a period of up to 1 week. 相似文献