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81.
Ondřej Linhart Alžběta Kolorosová-Mrázová Jan Kratzer Jakub Hraníček Václav Červený 《Analytical letters》2019,52(4):613-632
An ultraviolet-photochemical generator (UV-PVG) capable of post-column on-line transformation of both organic and inorganic mercury species to cold vapor (Hg0) with subsequent detection by quartz tube-atomic absorption spectrometry (QT-AAS) was developed. Mercury(II), methylmercury(I), ethylmercury(I), and phenylmercury(I) were successfully detected after separation by reversed-phase high-performance liquid chromatography (RP-HPLC). Two types of AAS detectors were compared. The first was a commonly used line-source instrument while the second was a high-resolution continuum source (HR-CS) AAS. The latter provided better limits of detection: 0.47?µg?L?1 for Hg(II), 0.84?µg?L?1 for methylmercury(I), 0.80?µg?L?1 for ethylmercury(I), and 2.0?µg?L?1 for phenylmercury(I). The repeatability at 30?μg?L?1 was 3.6%, 4.1%, 6.2%, and 4.5% for these species (n?=?10). These figures of merit were comparable with those reported for more sensitive atomic fluorescence spectrometry. Nine sample extraction procedures were investigated. Extraction by tetramethylammonium hydroxide and HCl at 75?°C was selected as the only method compatible with the proposed separation and detection steps providing high extraction efficiency and no changes in mercury speciation. The applicability of the proposed high-performance liquid chromatography–ultraviolet-photochemical vapor generation–quartz tube-atomic absorption spectrometry method was demonstrated using fish samples and certified reference materials (CRM) DOLT-4 (dogfish liver) and ERM-CE464 (tuna fish). The results were comparable to those obtained by a reference method based on L-cysteine extraction and high-performance liquid chromatography–inductively coupled plasma-mass spectrometry (HPLC–ICP-MS) determination. 相似文献
82.
Olga Hadžija 《Mikrochimica acta》1968,56(5):917-921
Summary Körbl-catalyst and manganese dioxide absorb chlorine and bromine quantitatively at room temperature. This property is applied to simultaneous microanalytical determination of carbon, hydrogen and chlorine or bromine in compounds containing carbon, hydrogen, oxygen, chlorine or bromine, but not nitrogen or sulphur.
Zusammenfassung Der Körbl-Katalysator und Mangandioxid absorbieren Chlor und Brom bei Raumtemperatur quantitativ. Sie wurden daher zur gleichzeitigen Bestimmung von C, H sowie Cl oder Br in Verbindungen verwendet, die C, H, O, Cl (oder Br), nicht aber N oder S enthalten.相似文献
83.
K. Južnič 《Mikrochimica acta》1983,80(5-6):345-348
Summary The sorption of Ce3+ from hydrochloric acid and its chromatography on a column filled with Dowex 50 X8 was studied. The break-through volumes and elution volumes, together with the sorption profile and band broadening were determined at different temperatures and are discussed. The Chromatographic results are interpreted in terms of cerium complex formation.
Über das Verhalten von Cerium(III) in salzsaurer Lösung
Zusammenfassung Die Sorption von Ce3+ aus salzsaurer Lösung in einer mit Dowex 50 X8 gefüllten Säule sowie dessen Chromatographie wurden untersucht. Die Durchbruchs- und Elutionsvolumina wurden bestimmt und diskutiert. Die Ergebnisse wurden im Sinne einer Komplexbildung interpretiert.相似文献
84.
A simple, rapid and accurate method for the spectrophotometric determination of chloride in non-polar media is described. The method is based on the well-known reaction of mercury(II) thiocyanate with chloride to release thiocyanate, which then reacts with iron(III). The optimum concentrations of reagents for the determination of chloride in 2,2,4-trimethylpentane (iso-octane) and cyclohexane are reported. The molar absorptivity of the complex at 505 nm is 5120 ± 200 dm3 mol?1 cm?1 for iso-octane and 5340 ± 340 dm3 mol?1 cm?1 for cyclohexane. Beer's Law is obeyed in the range 2 × 10?7–2 × 10?5 mol dm?3 (0.01–1 mg l?1) chloride. 相似文献
85.
The chelate compounds K[Fe(hyc)3] and N2H5[Fe(hyc)3]·H2O (hyc = N2H3COO) were studied by the Mössbauer effect of 57Fe at various temperatures. At room temperature the quadrupole splitting parameter is 2.77 mm/sec for K[Fe(hyc)3] and 2.35 mm/sec for N2H5[Fe(hyc)3]·H2O, and the center shift is 1.08 mm/sec for both compounds. The temperature dependences of the quadrupole parameters yielded the crystal field splittings of the 5T2g levels of the Fe2+ ions which indicate large trigonal distortion of the Fe(hyc)3 anion. Using a molecular crystal-like treatment of the ferrous ion vibrations the temperature dependence of the recoilless fraction gave an effective Debye temperature ΘD = 71°K for K[Fe(hyc)3] and ΘD = 90°K for N2H5[Fe(hyc)3]·H2O. No evidence for magnetic ordering was found down to 4.5°K in either compound. 相似文献
86.
V. Pažma 《Czechoslovak Journal of Physics》1979,29(5):481-486
A proposal for formulation of relativistic quantum mechanics in terms of path integrals is presented.We are deeply indebted to Dr. M.Petrá for many stimulating discussions. 相似文献
87.
Suszyńska M. Hartmanová M. Řežábková H. Lébl M. 《Czechoslovak Journal of Physics》1976,26(9):1011-1019
This paper presents the results of measurements of the mechanical and electrical properties of as-received pure and lead-doped crystals of potassium chloride. The critical resolved shear stress of the crystals obeys the Franks relationship
in the whole concentration range. In addition, the correlation between
0 and the Vickers hardness numberH was found and the equation is of the form
0=k (H–H
0). The solubility of Pb2+ in as-received KCl crystals was observed, from measurements of the electrical conductivity, to be low—the successive saturation of the solid solution started already in an environment of 5 mole ppm in agreement with data from the mechanical measurements. The density of cation vacancies and their mobility were represented by the following euqations
1
T=6·25×104 exp(–·75/kT) cm2 K/volt. sec,n
1=6·95×1023 exp(–2·12/kT) vacancies/cm3 The value of 0sd46±0·02 eV was found as a rough estimate of the association energy.The authors wish to express their thanks to Professor Dr. J. Z.Damm and Ing. E.Mariani for their stimulating interest in the present work. 相似文献
88.
89.
Synthesis and Rearrangement of P‐Nitroxyl‐Substituted PIII and PV Phosphanes: A Combined Experimental and Theoretical Case Study 下载免费PDF全文
Tobias Heurich Dr. Zheng‐Wang Qu Dr. Senada Nožinović Dr. Gregor Schnakenburg Dr. Hideto Matsuoka Prof. Dr. Stefan Grimme Prof. Dr. Olav Schiemann Prof. Dr. Rainer Streubel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):10102-10110
Low‐temperature generation of P‐nitroxyl phosphane 2 (Ph2POTEMP), which was obtained by the reaction of Ph2PH ( 1 ) with two equivalents of TEMPO, is presented. Upon warming, phosphane 2 decomposed to give P‐nitroxyl phosphane P‐oxide 3 (Ph2P(O)OTEMP) as one of the final products. This facile synthetic protocol also enabled access to P‐sulfide and P‐borane derivatives 7 and 13 , respectively, by using Ph2P(S)H ( 6 ) or Ph2P(BH3)H ( 11 ) and TEMPO. Phosphane sulfide 7 revealed a rearrangement to phosphane oxide 8 (Ph2P(O)STEMP) in CDCl3 at ambient temperature, whereas in THF, thermal decomposition of sulfide 7 yielded salt 10 ([TEMP‐H2][Ph2P(S)O]). As well as EPR and detailed NMR kinetic studies, indepth theoretical studies provided an insight into the reaction pathways and spin‐density distributions of the reactive intermediates. 相似文献
90.
Maja Trček George Cordoyiannis Brigita Rožič Vassilios Tzitzios George Nounesis Samo Kralj 《Liquid crystals》2017,44(10):1575-1581
We report on the stabilisation of the liquid-crystalline, twist-grain boundary A (TGBA) phase in mixtures of a chiral liquid crystal and surface-functionalised spherical Au nanoparticles (NPs) of 10 nm diameter. The results, obtained by calorimetric, optical, small-angle X-ray and plasmon resonance measurements, demonstrate that a TGBA phase, which is metastable for the pure liquid crystal host, can be effectively stabilised for a 3 K range in the presence of NPs. Moreover, the role of NPs size on the TGBA stabilisation is briefly discussed. 相似文献