共查询到20条相似文献,搜索用时 31 毫秒
1.
T. Keller Martin Mutz Rolf Aderjan Hans Peter Latscha 《Fresenius' Journal of Analytical Chemistry》1999,363(3):270-276
The polarographic behaviour of amphetamine-type drugs in acid and alkaline solutions was investigated. Differential pulse
polarography (DPP) with a dropping mercury electrode (DME) was used to monitor these drugs in aqueous solution. DPP and cyclic
voltammetry (CV) were also utilised to study the electrode process of some 2-phenylethylamines derivatised with 4-N,N-dimethylaminobenzaldehyde
(Ehrlich’s reagent) and 2,4-dinitrofluorobenzene, known as Sanger’s reagent, respectively.
Received: 19 March 1998 / Revised: 17 September 1998 / Accepted: 21 September 1998 相似文献
2.
R. D. Josephs R. Krska R. Schuhmacher M. Grasserbauer 《Fresenius' Journal of Analytical Chemistry》1999,363(1):130-131
The development of a rapid method for the determination of the Fusarium mycotoxin beauvericin (BEA) in corn and cereals is described. This method allows to prepare at least 5 times more samples
simultaneously with similar analytical performance characteristics as previously published analytical methods.
Received: 14 May 1998 / Revised: 9 July 1998 / Accepted: 14 July 1998 相似文献
3.
An enzyme-immunoassay for the detection of the mycotoxin zearalenone by use of yolk antibodies 总被引:1,自引:0,他引:1
H. Pichler R. Krska A. Székács M. Grasserbauer 《Fresenius' Journal of Analytical Chemistry》1998,362(1):176-177
The development of an enzyme-immunoassay (ELISA) for the detection of the Fusarium mycotoxin zearalenone (ZON) is described. In contrast to the common antibody isolation from mammal serum, chicken were immunized
in order to isolate specific antibodies from the egg yolk. Five weeks after the start of the immunization a titer of 1:76 000
resulted from three injections without any adverse effects for the animals. Utilizing the indirect competitive assay format
ZON could be detected in a concentration range between 10 and 200 μg/L.
Received: 3 January 1998 / Revised: 16 March 1998 / Accepted: 20 March 1998 相似文献
4.
Inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the element-specific determination of water-soluble
organosilicon species separated by high-performance liquid chromatography (HPLC). Leachates from different waste deposit sites
were investigated. The polydimethylsiloxane (PDMS) degradation product dimethylsilanediol (DMSD) could be detected in almost
all samples in the low mg L–1 range, and it was furthermore possible to determine trimethylsilanol (TMSOL) in some leachate samples in the μg L–1 range. TMSOL was additionally analyzed by a method established before (LT-GC/ICP-OES). This study proved the occurrence of
silanol compounds in leachates from locations were silicone material is deposited.
Received: 10 July 1998 / Revised: 2 November 1998 / Accepted: 5 November 1998 相似文献
5.
The dimerization reactions of ketene imine and bis(trifluoromethyl)ketene imine were studied theoretically. All the dimerization
processes take place in a concerted but asynchronous manner, each proceeding through a four-membered ring transition state.
For the ketene imine dimerization reactions, three different processes have almost equal activation barriers, while for the
three bis(trifluoromethyl)ketene imine dimerization processes the reaction giving symmetrical a four-membered heterocyclic
product has the lowest activation barrier.
Received: 15 July 1998 / Accepted 3 September 1998 / Published online: 17 December 1998 相似文献
6.
N. Furusawa 《Fresenius' Journal of Analytical Chemistry》1999,364(3):270-272
A method for the determination/identification of residual sulfadimidine (SDD) in milk and eggs by high-performance liquid
chromatography (HPLC) with a photo-diode array detector was developed. The sample preparation was performed by shaking with
a mixture of 20% (w/v) trichloroacetic acid-methanol (4:1, v/v) followed by ultra-filtration using Molcut II?. A LiChrospher? 100 RP-8 (e) column and a mobile phase of 4% (v/v) acetic acid solution-acetonitrile (6:4, v/v) were used. The average recoveries
from spiked SDD samples were 80.8–88.0% with coefficients of variation of 2.8–5.5%. The limits of detection in milk and eggs
were 0.01 μg/mL and 0.01 μg/g, respectively. The total time required for the analysis of one sample was less than 20 min.
Received: 7 October 1998 / Revised: 29 December 1998 / Accepted: 30 December 1998 相似文献
7.
The use of Brownian dynamics simulations to investigate the presence of structural (kinks) and dynamic (bulges) anomalies
in short DNA stretches is analyzed in connection with a string-of-beads model. A scaling method to choose the hydrodynamic
translational and rotational parameters of the beads is proposed and tested on straight, kinked and bulged DNA fragments 17 nm
long. The model reproduces the rigid-body rotational diffusion for the straight DNA and for the fluorescence polarization
anisotropy decay of the kinked and bulged DNAs the model predicts a different behavior which is found experimentally.
Received: 24 March 1998 / Accepted: 3 September 1998 / Published online: 23 November 1998 相似文献
8.
Iodine determination in biological materials
Options for sample preparation and final determination 总被引:1,自引:0,他引:1
G. Knapp B. Maichin P. Fecher S. Hasse P. Schramel 《Fresenius' Journal of Analytical Chemistry》1998,362(6):508-513
This paper describes the development of various new acid sample decomposition methods, as well as an extraction (leaching)
method and compares them with the “Sch?niger Combustion” technique. The methods have been developed as sample preparation
techniques for iodine determination in biological materials, especially in solid samples. ICP-MS (inductively coupled plasma
mass spectrometry) and a catalytic technique are employed and discussed for the final determination of iodine concentrations.
Accuracy and reliability of the different analytical methods are shown in the examples of different CRMs (certified reference
materials) available for iodine. The results of an interlaboratory comparison are specifically presented for the extraction
(leaching) method.
Received: 11 May 1998 / Revised: 14 June 1998 / Accepted: 16 June 1998 相似文献
9.
Qiaoyu Sun C. Wang Liangxi Li Hulin Li 《Fresenius' Journal of Analytical Chemistry》1999,363(1):114-117
A chemically modified carbon paste electrode was prepared by incorporating appropriate amounts of sodium humate(NaA). Palladium(II)
was selectively accumulated in a solution of Britton-Robinson(B-R) buffer (pH 2.8) onto the electrode surface in open circuit
mode. The subsequent electrochemical measurement was carried out by cyclic voltammetry (CV) and linear sweep anodic stripping
voltammetry (LSASV) in a supporting electrolyte of 1.0 M HCl. The obtained oxidation currents (Ipa1 and Lpa2) were proportional to the Pd(II) concentration in the range of 4.7 × 10–6 - 9.4 × 10–8 M. The developed method was applied to the quantitative determination of palladium in real samples.
Received: 6 March 1998 / Revised: 3 June 1998 / Accepted: 3 July 1998 相似文献
10.
Manuel Aguilar A. Farran Vicen? Martí 《Fresenius' Journal of Analytical Chemistry》1999,363(1):121-123
A CE method was developed for the determination of total (free and weakly bound) cyanide in electroplating solutions based
on the use of a cationic surfactant (TTAB) and complexation with Ni(II)-NH3 solutions to Ni(CN)4
2–. Both direct complexation and cyanide distillation combined with complexation were tested. Under optimized conditions, this
method is time-saving compared to standard methods. Total cyanide determined by CE had detection limits (with respect to the
initial sample concentration) of 0.5 μg/mL for direct complexation and 50 ng/mL for distillation combined with complexation.
Total cyanide and cyanide not amenable by chlorination (CNAC) were determined in real samples from spent electroplating baths.
Received: 5 February 1998 / Revised: 26 July 1998 / Accepted: 1 August 1998 相似文献
11.
F. Lagarde M. B. Amran M. J. F. Leroy C. Demesmay M. Ollé A. Lamotte H. Muntau P. Michel P. Thomas S. Caroli E. Larsen P. Bonner G. Rauret M. Foulkes A. Howard B. Griepink E. A. Maier 《Fresenius' Journal of Analytical Chemistry》1999,363(1):18-22
Tuna fishes were collected in the Straits of Messina (Italy), were dissected and dorsal muscles minced, freeze-dried, ground
and sieved. The obtained powder was stabilised by γ-irradiation and filled into brown glass bottles. The homogeneity and stability
at +20 °C and +40 °C were verified with regards to the total arsenic, dimethylarsinic acid and arsenobetaine contents. Ten
laboratories participated in the certification study. All participants had demonstrated beforehand their ability to produce
accurate results for the As speciation in fish tissue. The certified values are: total arsenic (4.8 ± 0.3) mg/kg, arsenobetaine
(52 ± 3) μmol/kg, dimethylarsinic acid (2.0 ± 0.3) μmol/kg. The material is available from the BCR since early 1998.
Received: 31 March 1998 / Revised: 20 July 1998 / Accepted: 25 July 1998 相似文献
12.
Wolfgang Quapp Michael Hirsch Dietmar Heidrich 《Theoretical chemistry accounts》1998,100(5-6):285-299
This paper serves for the better understanding of the branching phenomenon of reaction paths of potential energy hypersurfaces
in more than two dimensions. We apply the recently proposed reduced gradient following (RGF) method for the analysis of potential
energy hypersurfaces having valley-ridge inflection (VRI) points. VRI points indicate the region of possible reaction path
bifurcation. The relation between RGF and the so-called global Newton search for stationary points (Branin method) is shown.
Using a 3D polynomial test surface, a whole 1D manifold of VRI points is obtained. Its relation to RGF curves, steepest descent
and gradient extremals is discussed as well as the relation of the VRI manifold to bifurcation points of these curves.
Received: 8 July 1998 / Accepted: 24 August 1998 / Published online: 23 November 1998 相似文献
13.
An addition of sodium hypochlorite solution effectively eliminated the interference by sulfide in the cold vapor atomic absorption
spectrometric determination of mercury using tin(II) reduction in alkaline medium. Mercury ranging from 0.01 to 0.5 μg could
be determined within ±10% error in 100 mL of sample solution containing 10 mg of sulfide by the addition of 1 mL of 10.4%(w/v)
sodium hypochlorite solution. The proposed method is rapid (5 min per determination) and has good reproducibility (3.0%).
Received: 20 May 1998 / Revised: 7 July 1998 / Accepted: 10 July 1998 相似文献
14.
Yves Charreire Robert Cortes E. Nyk?nen L. Niinist? P. Soininen Markku Leskel? 《Fresenius' Journal of Analytical Chemistry》1998,362(1):41-50
Extended X-ray absorption fine structure (EXAFS) was used to determine the local structure of the luminescent centers in
Tb3+ and Ce3+ -doped strontium sulfide thin films deposited by Atomic Layer Epitaxy (ALE). The rare earths were observed to enter mainly
the substitutional sites but at the same time a part of the atoms form RES clusters (RE = rare earth). The presence of both
substitutional sites and RES clusters has been observed for the first time in this study for rare earths in II–VI compounds.
Received: 9 February 1998 / Revised: 22 May 1998 / Accepted: 29 May 1998 相似文献
15.
Molecular mechanics calculations were performed with the JUMNA program on d(GCGTGOGTGCG) · d(CGCACTCACGC) where “O” is a
modified abasic site: 3-hydroxy-2-(hydroxymethyl)tetrahydrofuran. From energy minimizations, for intrahelical or extrahelical
positions of the unpaired thymine, various structures with different curvatures were obtained. Dynamical properties of this
abasic sequence were also investigated through the controlled studies of DNA bending. Poisson-Boltzmann calculations were
used to mimic the electrostatic effect of solvent on this sequence. The lowest energy structures show an acceptable agreement
with experimental data.
Received: 1 June 1998 / Accepted: 17 September 1998 / Published online: 10 December 1998 相似文献
16.
S. Pozdniakova R. Ragauskas A. Dikčius A. Padarauskas 《Analytical and bioanalytical chemistry》1999,363(1):124-125
A capillary electrophoretic method for the determination of EDTA has been developed. EDTA was converted to Ni(II)-EDTA prior
to separation, separated from Fe(III)-EDTA, thiosulphate, bromide and polythionates using a fused silica capillary (57 cm
× 75 μm I.D.) filled with a borate buffer (50 mmol L–1; pH 8.5; applied voltage, 30 kV) and detected at 214 nm. The separation time is about 6 min. The detection limit achieved
is 2 × 10–6 mol L–1 for EDTA. This method was applied for the determination of free EDTA in used fixing solutions.
Received: 27 February 1998 / Revised: 28 April 1998 / Accepted: 20 May 1998 相似文献
17.
Mieczysaw Korolczuk Malgorzata Grabarczyk 《Fresenius' Journal of Analytical Chemistry》1999,363(4):421-423
A voltammetric determination of Cr(VI) in a flow system is described based on the selective accumulation of the reduction
product of Cr(VI) on an HMDE, its complexation with DTPA and subsequent reduction of the complex in presence of nitrate. The
calibration graphs were linear up to 100 and 5 nmol/L for deposition times 120 and 600 s, respectively. The relative standard
deviation was 2.8% (n = 5) for Cr(VI) concentrations of 5 × 10–8 mol/L. The detection limits (3 σ) for Cr(VI) were 1.0 and 0.12 nmol/L at deposition times of 120 and 600 s, respectively.
Typical interferences derived from real water samples are discussed. The method has been applied for the determination of
Cr(VI) in spiked natural water samples.
Received: 18 June 1998 / Revised: 28 September 1998 / Accepted: 5 October 1998 相似文献
18.
S. Pozdniakova R. Ragauskas A. Dikius A. Padarauskas 《Fresenius' Journal of Analytical Chemistry》1999,363(1):124-125
A capillary electrophoretic method for the determination of EDTA has been developed. EDTA was converted to Ni(II)-EDTA prior
to separation, separated from Fe(III)-EDTA, thiosulphate, bromide and polythionates using a fused silica capillary (57 cm
× 75 μm I.D.) filled with a borate buffer (50 mmol L–1; pH 8.5; applied voltage, 30 kV) and detected at 214 nm. The separation time is about 6 min. The detection limit achieved
is 2 × 10–6 mol L–1 for EDTA. This method was applied for the determination of free EDTA in used fixing solutions.
Received: 27 February 1998 / Revised: 28 April 1998 / Accepted: 20 May 1998 相似文献
19.
Yuri A. Karpov 《Accreditation and quality assurance》1999,4(5):174-176
Specific features of the procedures involved in chemical analysis (sampling, sample preparation, matrix and impurities identification,
quantitative analysis) are considered, and their effect on the uncertainty of the result of a quantitative determination of
the component of interest is discussed.
Received: 19 August 1998 / Accepted: 4 September 1998 相似文献
20.
P. Quevauviller M. J. Benoliel R. Neves Carneiro L. Cortez 《Fresenius' Journal of Analytical Chemistry》1999,363(1):23-27
The quality control of groundwater monitoring requires the availability of representative CRMs. This paper describes the preparation
of two artificial groundwater reference materials, CRM 616 (high carbonate content) and CRM 617 (low carbonate content), the
homogeneity and stability studies and the analytical work performed for the certification of a range of major elements (Ca,
Cl, Fe, K, Mg, Mn, Na, NO3, PO4 and SO4).
Received: 15 May 1998 / Revised: 25 June 1998 / Accepted: 1 July 1998 相似文献