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991.
R. Usón A. Laguna J. Vicente J. García B. Bergareche 《Journal of organometallic chemistry》1979,173(3):349-355
(Pentahalophenyl) (p-tolylisocyanide)gold(I) complexes were prepared by treating Au(C6X5) (tetrahydrothiophen) (X = F, Cl or Br) with p-MeC6H4NC. Their reactivity toward nucleophiles was studied and found to decrease in the sequence: primary amines > ammonia > secondary amines > aromatic amines > alcohols; the effects of the various C6X5 groups were less pronounced, but decreased according to C6F5 > C6Cl5 > C6Br5.Twenty-five novel gold(I) carbene derivatives were isolated. 相似文献
992.
Summary The influence of Cr2O7
2–, MnO4
–, Ce4+, H2O2 and S2O8
2– as oxidising agents in lead determination as volatile covalent hydride using NaBH4 is reported in this paper.The reaction conditions for every oxidising agents (pH, quantity and concentration of the oxidising agent, quantity and concentration of the NaBH4 and reaction time) are optimized, determining sensitivity and detection limit by measuring the peak height.The recovery of lead from solution has been measured by flameless atomic absorption spectroscopy.A linear relationship the logarithm of absorbance values and the redox potential of the system is obtained with a correlation coefficient of 0.999. The results and their interpretation are given in this paper.
Paper presented to Euroanalysis V. Cracow, August 1984. 相似文献
Der Einflu oxidierender Reagentien auf die Bleibestimmung mittels Flammenatomabsorptionsspektrometrie nach Hydridbildung
Zusammenfassung Es wird über den Einfluß der Oxidantien Cr2O7, MnO4 –, Ce4+, H2O2 und S2O8 2 – auf die Bleibestimmung als kovalentes Hydrid berichtet. Für jede oxidierende Substanz werden die Reaktionsbedingungen optimiert (pH, Menge und Konzentration des Oxidans, Menge und Konzentration von NaBH4 und Reaktionszeit), um Empfindlichkeit und Nachweisgrenze durch Peakhöhenauswertung zu bestimmen.Die Wiederfindungsrate wurde durch elektrothermale Atomabsorptionsspektrometrie von Blei in der Lösung bestimmt.Der Zusammenhang zwischen dem Logarithmus der Extinktion und dem Redoxpotential des Oxidans ergibt eine lineare Beziehung mit einem Korrelationskoeffizienten von 0.999. Die Ergebnisse und deren Interpretation werden in dieser Arbeit beschrieben.
Paper presented to Euroanalysis V. Cracow, August 1984. 相似文献
993.
The
aim of our research was to prepare yellow pigments based on structure of pseudobrookite
Fe2TiO5. Part of Fe was substituted
with Li and Ti from Fe2TiO5
to Li0.05Fe0.07Ti2.44O5.
Synthesis and pigmentary-application properties in the Li2O–Fe2O3–TiO2 system were studied for 800 and 900°C using classical ceramic
method of preparation. The main attention was aimed to usage of four different
sources of titanium compounds as raw materials. We studied the influence of
different sources of titanium compounds on the structural and the colour properties
of the prepared pigments. The thermal analysis was used for characterization
of titanium compounds and determination of their thermal stability. 相似文献
994.
Doyle EL García F Humphrey SM Kowenicki RA Riera L Woods AD Wright DS 《Dalton transactions (Cambridge, England : 2003)》2004,(5):807-812
The reaction of [ClP(mu-NtBu)]2 (1) with H2O (1 : 2 equivalents) in the presence of excess Et3N gives the new chain compound [(mu-O)[P(mu-NtBu)2P(H)=O]2] (3), consisting of two P2N2 rings linked by a mu-O atom and terminating in P(V)(H)=O groups. A similar chain species is obtained from the reaction of the lithiate of [(tBuNH)P(mu-NtBu)2P(H)=O] (5) with [ClP(mu-NtBu)2P(NHtBu)] (2), the product being [(mu-O)[P(mu-NtBu)2P(NHtBu)]2] (6). Compounds 3 and 6 are the first examples of O-bridged chain phosphazanes and potential precursors to new phosphorus-nitrogen macrocycles. The syntheses and X-ray structures of 3, 5 and 6 are reported. 相似文献
995.
Martínez-Galera M López-López T Gil-García MD Martínez-Vidal JL Picón-Zamora D Cuadros-Rodríguez L 《Analytical and bioanalytical chemistry》2003,375(5):653-660
A comparative study of two mathematical approaches was performed in order to correct systematic errors due to the presence of the unexpected interferences which appear when the quantitation of the analyte in real samples is carried out with calibration curves built using standards in pure solvent. These methods consisted in the establishment of different mathematical expressions which transform the concentration (Cs) obtained using calibration graphs built using pure solvent into the corrected concentration (C(M)) that should be obtained if the quantitation is carried out with calibration curves built using standards dissolved in blank matrix extracts. In the two approaches the correction is performed from the results of an intermediate precision study which was carried out using both calibration graphs (prepared using pure solvent and blank matrix extract). By using ANCOVA to compare the slope of both solvent-based and matrix-matched calibration graphs, matrix effect was found in the determination of deltamethrin in tomato and acrinathrin in tomato and pepper. In these cases, both approaches led to good results. 相似文献
996.
C. Carnero Ruiz J. Molina-Bolívar J. Aguiar G. MacIsaac S. Moroze R. Palepu 《Colloid and polymer science》2003,281(6):531-541
The aggregation behaviour of Tween 20 in ethylene glycol-water mixed solvents has been investigated using surface tension, density, static and dynamic light scattering, and fluorescence measurements. Micellar and surface thermodynamics data were obtained from the temperature dependence of critical micelle concentrations in various aqueous mixtures of ethylene glycol. In order to evaluate the influence of the cosolvent, the differences in the Gibbs energies of micellization of Tween 20 between water and binary solvents were determined. This study allowed us to conclude that the ability of ethylene glycol to act as a structure breaker and its interaction with the surfactant hydrophilic group are the controlling factors of the micellization process. From the evaluation of the thermodynamics of adsorption at the solution-air interface, it was determined that the surface activity of the surfactant decreases slightly with increasing concentration of ethylene glycol at a given temperature. Partial specific volume data, obtained by density measurements, indicate that the fraction of solvent molecules interacting with the micelle, via hydrogen bonds, remained roughly constant. The effect of cosolvent on the size and solvation of the aggregates was analysed by means of static and dynamic light scattering measurements. It was found that the aggregation number decreased, whereas the whole micellar solvation increased with the ethylene glycol content. Micellar micropolarity was examined using two different probes, pyrene and 8-anilinonaphthelene-1-sulfonic acid, and was found to increase with ethylene glycol addition, accompanied by an enhanced solvation. Fluorescence polarization measurements found by using coumarin 6 as a hydrophobic probe revealed an increase in the micellar microviscosity. The observed trends in these microenvironmental properties were ascribed to a participation by ethylene glycol in the micellar solvation layer. 相似文献
997.
Manuel Cano Beatriz Palenzuela J. Luis Ávila Rafael Rodríguez‐Amaro 《Electroanalysis》2007,19(9):973-977
A PVC/TTF‐TCNQ composite electrode has been employed as detector in a flow injection system. The proposed method allows the simultaneous detection of ascorbic acid (AA) and uric acid (UA) in mixtures by using a FIA system in a simple manner, without pre‐treatment or modified electrode. This method is based on the amperometric determination of (a) ascorbic acid at 0.15 V and (b) both analytes at 0.35 V, being the response linear in the range 1×10?2–4×10?4 M for both analytes with detection limits (S/N=3) of 1.2×10?4 M and 8.1×10?5 M for AA and UA, respectively. 相似文献
998.
Z. Řanda M. Vobecký J. Kuncír J. Benada 《Journal of Radioanalytical and Nuclear Chemistry》1978,46(1):95-107
The application of multielement standards (MES) in routine neutron activation analysis brings a whole range of advantages.
This paper deals with the experience obtained during many years of application of these MES. Nine of these MES contain a total
of 50 elements in suitable combinations and concentrations; thus, the determination of most of the common elements by NAA
can be carried out simultaneously. This refers to the following elements: Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni,
Cu, Zn, Ga, As, Se, Br, Rb, Sr, Mo, Ag, Cd, In, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf,
W, Re, Au, Hg, Th and U. For the determination of the remaining elements such as Zr, Ta, Ir etc., single element standards
(SES) are used. 相似文献
999.
Vidal JL Vega AB Arrebola FJ González-Rodríguez MJ Sánchez MC Frenich AG 《Rapid communications in mass spectrometry : RCM》2003,17(18):2099-2106
A fast method for the determination of eight organotin compounds (OTs), monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), tetrabutyltin (TeBT), monophenyltin (MPhT), diphenyltin (DPhT), triphenyltin (TPhT) and tetraphenyltin (TePhT), in water, sediments and mussels, was developed using low-pressure gas chromatography/tandem mass spectrometry (LPGC/MS/MS). The method is based on sodium diethyldithiocarbamate (DDTC) complexation of the ionic organotins, followed by extraction of the target matrices and derivatization by a Grignard reagent, as described in a previously published method for water samples. Solid-phase extraction was selected as extraction method from water samples after comparison with liquid-liquid extraction, but extraction of the OTs from sediment and mussel samples was performed using toluene. Matrix-matched calibration standards were used to minimize matrix effects. The analytical process was validated by the analysis of spiked blank samples. Performance characteristics such as linearity, detection limit (LOD), quantitation limit (LOQ), precision, and recovery were determined. Recoveries of OTs in spiked matrices ranged from 86-108% in water and from 78-110% in sediments and mussels, with precision values lower than 18%. Detection limits ranged from 0.1-9.6 ng L(-1) in water, and 0.03-6.10 microg kg(-1) in the other matrices. The present implementation of LPGC rather than conventional capillary GC permitted use of large-volume injection and reduced analysis time by a factor of two. The proposed methodology was applied to the determination of OTs in real samples of water, marine sediments and mussels from the west coast of the Mediterranean Sea (Spain). 相似文献
1000.
Davies SG Díez D El Hammouni MM Garner AC Garrido NM Long MJ Morrison RM Smith AD Sweet MJ Withey JM 《Chemical communications (Cambridge, England)》2003,(19):2410-2411
Comparison of the kinetic and parallel kinetic resolutions of methyl (RS)-5-tert-butyl-cyclopentene-1-carboxylate allows for the efficient synthesis of both (1R,2S,5S)- and (1S,2R,5R)-enantiomers of methyl 2-amino-5-tert-butyl-cyclopentane-1-carboxylate. 相似文献