共查询到20条相似文献,搜索用时 62 毫秒
1.
S. Iskric B. Kojic-Prodic B. Spoljar R. Kiralj O. Hadzija 《Analytical and bioanalytical chemistry》1997,357(7):897-900
The complexes formed between Cu(II), Pb(II), Cd(II), Zn(II) and Hg(II) salts and some aromatic humic-like complexants in
the chromatographic process, simulating natural conditions, were investigated by X-ray powder diffraction and IR-spectroscopic
analyses; most of the complexes formed were identified.
Received: 20 June 1996/Revised: 20 August 1996/Accepted: 23 August 1996 相似文献
2.
Nonionic surfactants are widely used in commercial formulations as complex mixtures requiring efficient and selective separation
methods. Capillary electrophoretic separations were carried out in electrolytes containing high amounts of organic solvents
and anionic surfactants based on the formation of association complexes between analytes and anionic surfactants without micelle
formation. Octyl- and nonylphenol polyethoxylates were separated as their ethoxylate homologues. Influences of the electrophoretic
conditions like electrolyte concentration and pH, type and content of anionic surfactant and organic solvents were investigated.
Received: 12 February 1996/Revised: 21 May 1996/Accepted: 5 June 1996 相似文献
3.
Differential pulse anodic stripping voltammetry (DPASV), potentiometry with a copper ion-selective electrode and a kinetic
photometric method were used to determine copper species in white wines. The kinetic method is based on the catalytic effect
of labile copper(II) species on the oxidation of 3-hydroxybenzaldehyde azine by potassium peroxidisulfate in an ammonical
medium at room temperature. The total copper concentrations were determined by flame atomic absorption spectrometry. Free
copper(II) ions, labile and tightly bound copper species could be quantified in 16 non pre-treated wine samples.
Received: 13 August 1996 / Revised: 28 October 1996 / Accepted: 29 November 1996 相似文献
4.
Capillary electrochromatographic separation of amino acid enantiomers with molecularly imprinted polymers as chiral recognition agents 总被引:3,自引:0,他引:3
J.-M. Lin Tatsuro Nakagama Xing-Zheng Wu Katsumi Uchiyama Toshiyuki Hobo 《Analytical and bioanalytical chemistry》1997,357(1):130-132
The use of molecularly imprinted polymers polymerized in a capillary for the separation of amino acid enantiomers by electrochromatography
is described. The substrate-selective polymers were prepared by using l-phenylalanine anilide as print molecule and methacrylic acid as the functional monomer. The treatment of the inside surface
of the capillary, the composition of the polymer and the electrochromatographic running conditions were investigated. This
preliminary report demonstrated a novel and simple method for capillary electrochromatographic separations of amino acid enantiomers
using molecularly imprinted polymers.
Received: 9 April 1996 / Revised: 8 August 1996 / Accepted: 8 August 1996 相似文献
5.
Differential pulse anodic stripping voltammetry (DPASV), potentiometry with a copper ion-selective electrode and a kinetic
photometric method were used to determine copper species in white wines. The kinetic method is based on the catalytic effect
of labile copper(II) species on the oxidation of 3-hydroxybenzaldehyde azine by potassium peroxidisulfate in an ammonical
medium at room temperature. The total copper concentrations were determined by flame atomic absorption spectrometry. Free
copper(II) ions, labile and tightly bound copper species could be quantified in 16 non pre-treated wine samples.
Received: 13 August 1996 / Revised: 28 October 1996 / Accepted: 29 November 1996 相似文献
6.
An analytical method is described to determine simultaneously cis/trans N-n-alkyl-dimethylmorpholines and their metabolites,
the 4-(ω-carboxy-n-alkyl) cis/trans-2,6-dimethylmorpholines by pyrolytic alkylation and high resolution GC/MS in aqueous systems
and sediments. The substances in the sediment phase were analyzed by GC/MS after extraction with methanol and water, substances
in the water phase could be directly determined by GC/MS. The analytical procedure also allows the determination of further
carboxylic acids in complex aqueous systems.
Received: 9 April 1996 / Revised: 10 June 1996 / Accepted: 14 June 1996 相似文献
7.
C. Dubourdieu N. Didier O. Thomas J. P. Sénateur N. Valignat Y. Rebane T. Kouznetsova A. Gaskov J. Hartmann B. Stritzker 《Analytical and bioanalytical chemistry》1997,357(8):1061-1065
Some YBa2Cu3O7-δ films and heterostructures prepared by Chemical Vapor Deposition (CVD) were analyzed in our laboratories by EPMA-EDX or WDX,
RBS, SNMS and AES. It was found that in some cases the results of composition analysis can significantly deviate from each
other. At least two main reasons for these deviations exist: the different lateral resolution and the application of different
reference samples for the calibration.
Received: 3 June 1996 / Revised: 14 October 1996 / Accepted: 16 October 1996 相似文献
8.
First experiences with the technique of acoustical levitation of droplets in the field of analytical and atmospheric chemistry
are reported. Acoustical levitation enables the contactless handling of solid and liquid microsamples. This avoids adsorption
of analyte at and desorption of contaminants from container walls especially for liquid samples. Common experiments of sample
preparation procedures were conducted in levitated drops like liquid/liquid extractions, solvent exchange, and analyte enrichment
by evaporation of the solvent. A first approach was made to use acoustical levitation for the simulation of atmospheric chemistry
situations.
Received: 10 October 1996 / Revised: 25 October 1996 / Accepted: 25 October 1996 相似文献
9.
A collaborative study of 209 PCB congeners and 6 Aroclors on 20 different HRGC columns
1. Retention and coelution database 总被引:2,自引:0,他引:2
George M. Frame 《Analytical and bioanalytical chemistry》1997,357(6):701-713
The elution orders and predicted coelutions of all 209 PCB congeners were obtained for 27 HRGC-ECD or HRGC-MS systems comprising
20 different stationary phases. The resultant database facilitates selection of the columns most suitable for developing particular
comprehensive, quantitative, congener-specific PCB analyses, the design of the minimum number of congener mixtures needed
to calibrate such analyses, and the testing of retention prediction algorithms based on structure relationships of GC phases
and congener substitution patterns.
Received: 24 March 1996 / Revised: 4 July 1996 / Accepted: 6 July 1996 相似文献
10.
G. Woelki S. Friedrich G. Hanschmann R. Salzer 《Fresenius' Journal of Analytical Chemistry》1997,357(5):548-552
Different soil extracted humic acids as well as a commercial humic acid sodium salt were fractionated by HPLC. An almost
complete recovery could be achieved for the dissolved material. All humic samples show a typical chromatogram of at least
five fractions. The separation of humic substances is influenced by an altered hydrophobicity due to changes in the tertiary
structure. Three fractions were further investigated by Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy
and by HPLC/HPLC separation. DRIFT spectroscopy provided data on the primary structure, whereas HPLC/HPLC results gave insight
into the secondary and tertiary structure and their changes.
Received: 18 June 1996 / Revised: 9 October 1996 / Accepted: 12 October 1996 相似文献
11.
A combination of non-linear variable-angle synchronous fluorescence spectrometry with the derivative technique has been developed.
A rapid simultaneous identification and quantitative determination of acenaphthene, carbazole, anthracene, 9,10-dimethylanthracene
and perylene were achieved from a single spectrum by non-linear variable-angle synchronous fluorescence and combined derivative
non-linear variable-angle synchronous fluorescence. The latter approach offered a further improvement in spectral resolution
and analytical sensitivity. The usefulness of the proposed method was confirmed by adding known amounts of these five polynuclear
aromatic compounds to the extract of waste water samples.
Received: 5 August 1996/Revised: 11 September 1996/Accepted: 14 September 1996 相似文献
12.
A combination of non-linear variable-angle synchronous fluorescence spectrometry with the derivative technique has been developed.
A rapid simultaneous identification and quantitative determination of acenaphthene, carbazole, anthracene, 9,10-dimethylanthracene
and perylene were achieved from a single spectrum by non-linear variable-angle synchronous fluorescence and combined derivative
non-linear variable-angle synchronous fluorescence. The latter approach offered a further improvement in spectral resolution
and analytical sensitivity. The usefulness of the proposed method was confirmed by adding known amounts of these five polynuclear
aromatic compounds to the extract of waste water samples.
Received: 5 August 1996/Revised: 11 September 1996/Accepted: 14 September 1996 相似文献
13.
G. Woelki S. Friedrich G. Hanschmann R. Salzer 《Analytical and bioanalytical chemistry》1997,357(5):548-552
Different soil extracted humic acids as well as a commercial humic acid sodium salt were fractionated by HPLC. An almost
complete recovery could be achieved for the dissolved material. All humic samples show a typical chromatogram of at least
five fractions. The separation of humic substances is influenced by an altered hydrophobicity due to changes in the tertiary
structure. Three fractions were further investigated by Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy
and by HPLC/HPLC separation. DRIFT spectroscopy provided data on the primary structure, whereas HPLC/HPLC results gave insight
into the secondary and tertiary structure and their changes.
Received: 18 June 1996 / Revised: 9 October 1996 / Accepted: 12 October 1996 相似文献
14.
The high mass range time-of-flight secondary ion mass spectra of different polyarene films on silver
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to investigate thin films of poly(styrene), poly(vinyl
napthalene), and poly(4-chlorostyrene) on clean silver substrate surfaces. The mass spectra were taken in the high molecular
mass range (m/z>1000 amu). The different fragmentation patterns found are discussed in detail. Obviously, the fragmentation
mechanisms are influenced by the electron density of the aryl rings stabilizing or destabilizing the formed cations.
Received: 10 April 1996 / Revised: 12 June 1996/Accepted: 14 June 1996 相似文献
15.
F. A. Guimelfarb Mikhail N. Filippov Elena V. Kletskina 《Analytical and bioanalytical chemistry》1997,357(7):796-800
A new method of electronprobe microanalysis (EPMA) is suggested. It is based on creating ionic conductivity in frozen water
solutions and in polymer films by doping them with a salt. This procedure is effective to prevent surface charging and allows
imaging of nonconducting samples by scanning electron microscopy (SEM) as well as X-ray microanalysis. Specifically, this
procedure makes it possible to perform EPMA of samples with xerogel matrices, which were used for molecular laser microprobe
mass spectrometry analysis, and consequently to provide complex microprobe examination of samples.
Received: 24 January 1996 / Revised: 4 July 1996 / Accepted: 16 July 1996 相似文献
16.
N. Cardellicchio S. Cavalli V. Piangerelli S. Giandomenico P. Ragone 《Fresenius' Journal of Analytical Chemistry》1997,358(6):749-754
A reverse-phase high-performance liquid chromatography procedure with gradient elution and electrochemical detection is described
for the determination of phenolic compounds, including several priority pollutant chlorophenols, in sea-water and sediments.
In addition, a method for concentrating phenols from sea-water was examined. A solid-phase extraction using a derivatized
poly(styrene-divinylbenzene) copolymer is discussed. The recovery, repeatability and detection limits are shown. Electrochemical
detection provided selectivity as well as sensitivity. Phenols at the ng/l level were detected. The method was applied to
the analysis of the most important phenolic compounds in sea-water and marine sediments.
Received: 12 April 1996 / Revised: 30 October 1996 / Accepted: 28 November 1996 相似文献
17.
W. Bögershausen R. Cicciarelli B. Gercken E. König V. Krivan R. Müller-Käfer J. Pavel H. Seltner J. Schelcher 《Analytical and bioanalytical chemistry》1997,357(3):266-273
Seven synthetic graphite powders of different grade of purity were analyzed by means of INAA, WDXRF, EDXRF, DC-OES directly
and using ICP-MS, ICP-OES, ETAAS and FAAS in combination with various sample preparation techniques. On the basis of a statistical
evaluation of the results obtained, for the trace elements Al, Ca, Cr, Cu, Fe, Mn and Ni, reference values were established
and, for the elements As, Co, Mg, Mo, Pb, Sb, Si, Sr, Ti, V, Zn and Zr, informative values are given. The analyzed reference
materials are commercially available.
Received: 12 February 1996/Revised:27 March 1996/Accepted:2 April 1996 相似文献
18.
Methods are described for the accurate and precise determination of lead concentrations and the isotopic composition of lead
in wine samples using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). This method needs little sample preparation.
A comparison with lead isotope ratios measured by Thermal Ionization Mass Spectrometry (TIMS) in three wine samples reveals
a good agreement between the two techniques. The lead concentration in three certified wine samples were measured by isotope
dilution (ID) and the results are compared with those obtained by external calibration ICP-MS.
Received: 10 June 1996/Revised: 23 September 1996/Accepted: 30 September 1996 相似文献
19.
M. Schmeling F. Alt R. Klockenkämper D. Klockow 《Analytical and bioanalytical chemistry》1997,357(8):1042-1044
Total reflection X-ray fluorescence spectrometry was applied for the certification of IAEA lichen-336. The elements Ca, Mn,
Fe, Cu, Zn, Rb, Sr and Pb were determined simultaneously. The concentrations range from 1.8 mg/kg for Rb to 2360 mg/kg for
Ca. The results were compared with those of other methods and laboratories having participated in this certification for the
International Atomic Energy Agency (IAEA): emission spectrometry, mass spectrometry, atomic absorption spectrometry, X-ray
spectrometry, neutron activation analysis and voltammetry. The results determined by TXRF are in good agreement with the overall
means of accepted values and differ from the means by 1 to 10%.
Received: 1 September 1996/Revised: 15 October 1996/Accepted: 22 October 1996 相似文献
20.
Matthias Heydenreich Andreas Koch E. Kleinpeter Thomas Zimmermann 《Fresenius' Journal of Analytical Chemistry》1997,357(5):517-521
Dynamic NMR investigations of a number of 2-amino-3-aroyl-4,6-diaryl-pyrylium salts were carried out. The barrier to rotation
of the partial C, N double bond was determined and proved to be in the range of 62 to 63 kJ/mol. Quantum chemical calculations
of bond orders and electron densities of the different atoms in the molecules show the distinct double bond character of the
exocyclic C, N bond. This is in agreement with the relatively high barrier to rotation. By quantum chemical ab initio 3-21G
calculations, the dynamic behaviour of this kind of compounds was simulated; two pairs (image and mirror image) of ground
state conformations, in coincidence with the experiment, were obtained.
Received: 10 May 1996 / Revised: 1 July 1996 / Accepted: 4 July 1996 相似文献