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1.
Instrumental neutron activation analysis (INAA) can now directly be applied to samples with masses in the kilogram range. It enables the analysis of material which is considered to be not representative at the scale of the traditional analytical portion, but representative at much larger scale. Large sample INAA (LS-INAA) circumpasses various problems associated with sample-size reduction and homogenization. Examples of feasibility studies are given as on construction waste, contaminated soil, harbour sediment and recyclable material. Also the economics of this method of analysis is discussed. 相似文献
2.
Instrumental neutron activation analysis (INAA) has been employed as an absolute method for the determination of the stoichiometry
of mixed microcrystals K xCs yZnCl 4 with a weight ranging between 20 and 50 μg. The reliability of the method has been checked with the pure substances KCl,
NaCl, CsCl and RbCl, for which the mean value of the ratio Cl/X was found to be 1.04 (3).
Received: 26 May 1997 / Revised: 1 July 1997 / Accepted: 2 July 1997 相似文献
3.
Instrumental neutron activation analysis (INAA) has been employed as an absolute method for the determination of the stoichiometry
of mixed microcrystals K xCs yZnCl 4 with a weight ranging between 20 and 50 μg. The reliability of the method has been checked with the pure substances KCl,
NaCl, CsCl and RbCl, for which the mean value of the ratio Cl/X was found to be 1.04 (3).
Received: 26 May 1997 / Revised: 1 July 1997 / Accepted: 2 July 1997 相似文献
4.
Instrumental Neutron Activation Analysis (INAA) is employed for its important analytical properties. Fundamentally, INAA is a multi-elemental technique allowing the determination of about 40 elements with a good Limit of Detection. In this paper we applied this nuclear technique to study the element composition in PM10 determining about 30 elements.25 filters were collected in downtown Rome from October 1999 to April 2000 and irradiated at the nuclear reactor Triga Mark II (ENEA-Casaccia Laboratories). The γ-ray measurements have allowed the quali- and quantitative analysis. The element levels in PM10 with the relative correlations have been determined: basically, the concentrations are very low.Furthermore, the enrichment factors of all elements will be reported in order to understand the natural or anthropogenic origins of the particulate matter: some elements may be attributed to long-range transport phenomena from other natural and/or anthropogenic sources. 相似文献
5.
Many modern analytical techniques use small solid samples and lack proper reference materials for their calibration and quality
assurance. A remedy to this deficiency may be in the development of a new genre of highly homogeneous natural matrix materials,
their properties being studied with analytical techniques such as PIXE and μ-PIXE, solid sampling AAS, scanning electron microscopy
in combination with electron probe X-ray microanalysis, and INAA. Suitable natural materials may be obtained in form of single
cell biological materials, finely dispersed suspensions and precipitates such as air particulate matter or sediments, and
by appropriate particle size reduction of complex matrices. Initial studies have been carried out on single cell green algae
biomass and air particulate matter, as well as several processed materials. Narrow particle size distributions with particles
preferably below 10 μm diameter may assure the desired analytical homogeneity. The determination of sampling parameters for
individual measurands will ascertain the utility of a material for small-sample analysis.
Received: 16 June 1997 / Revised: 24 September 1997 / Accepted: 27 September 1997 相似文献
6.
We have established an instrumental neutron activation analysis (INAA) method, including k0-based INAA, at the Korea Research Institute of Standards and Science (KRISS) for the certification of reference materials. As part of establishing INAA measurements, KRISS infant formula certified reference material was analysed for multiple elements at three different metrological institutes: KRISS and NIST for the standard comparator method, and JSI for the k0-INAA method. The mass fraction of most elements was consistent within expanded uncertainty (k?=?2). In addition, the results were used to verify the validity of elemental analysis of Zn using the standard comparator INAA at KRISS, and spreadsheet-based INAA calculations were evaluated. 相似文献
7.
In a series of three papers, the inherent characteristics of relative instrumental neutron activation analysis (INAA) as a
primary ratio method of measurement, the unique functions of parametric INAA as an ideal back-up method of the relative INAA,
and the valuable role of INAA in characterization of sampling behavior of individual elements in certified reference materials
(CRMs) will be discussed. In this paper, the first of the series, the uncertainty evaluation and the traceability of values
measured by neutron activation analysis (NAA), especially instrumental NAA (INAA), will be described to demonstrate the method
at its ”the state-of-the-art” level can meet CCQM criteria for a primary ratio method. The scope and examples will be given.
Received: 19 March 2001 Accepted: 2 October 2001 相似文献
8.
Milk was collected over a four-month period from three representative sectors of Puerto Rico. Instrumental neutron activation
analysis (INAA) performed on the samples showed that the mercury concentration was slightly higher than the safe upper limit
set by the World Health Organisation on food products. INAA for cadmium yielded high values when compared with atomic absorption. 相似文献
9.
A monoclonal antibody (Mab) with extraordinary sensitivity and high class selectivity to triazine herbicides is described.
With an enzyme-linked immunosorbent assay (ELISA) using Mab 4A54 IC 50 values for terbuthylazine, atrazine, propazine and simazine below 0.1 μg/L (the EU maximum admissible concentration for individual
pesticides) have been obtained. Detection limits of 0.004 μg/L for terbuthylazine, 0.006 μg/L for atrazine, 0.003 μg/L for
propazine, 0.01 μg/L for simazine and 0.05 μg/L for deethylterbuthylazine could be achieved. Therefore, Mab 4A54 allows a
sum screening of these five triazines in a relevant concentration range. To our knowledge, this is the most sensitive antibody
to terbuthylazine at all and also the most sensitive Mab to all these four triazines. Another monoclonal antibody resulting
from the same immunization, clone 4A118, exhibits best sensitivity for propazine (detection limit: 0.02 μg/L) at lower cross-reactivity
to terbuthylazine and atrazine compared to clone 4A54. Affinity constants of both Mabs towards several triazines have been
calculated. The application of both Mabs for the analysis of triazines in water samples of different origin has been tested
and their resistance towards humic acid influence could be shown. A good correlation of the analysis of water samples with
GC and ELISA was observed.
Received: 17 February 1997 / Revised: 1 April 1997 / Accepted: 3 April 1997 相似文献
10.
A new and efficient Hg(II) back-elution method for the desorption of Cd, Cu, and Pb from Chelex-100 chelating resin was developed.
A smaller eluent volume and shorter elution time can be achieved using an Hg(II) containing eluent rather than pure nitric
acid. Owing to the remaining Hg(II) ion in the effluent, a mercury thin-film electrode is formed in-situ during the anodic
stripping voltammetric determination without any further addition of Hg(II). The results indicate that all the analytes in
seawater matrix can be completely adsorbed on Chelex-100 resin from the sample at pH 6.5, and subsequently eluted from the
resin with an acid solution of 5 × 10 –4 mol/L Hg 2+ + 1 mol/L HClO 4. The detection limits obtained from the differential-pulse anodic (μg L –1 to ng L –1) stripping voltammetry are at sub-ppb to ppt (μg L –1 to ng L –1) levels permitting to determine Cd, Cu and Pb traces in seawater. The analytical reliability was confirmed by the analysis
of the certified reference material CASS-II (open ocean seawater).
Received: 22 April 1997 / Revised: 5 August 1997 / Accepted: 7 August 1997 相似文献
11.
Using the Z-vector formalism the analytical gradient of the energy in small CI expansions is derived and implemented for
semiempirical MNDO-type methods. The computation time is shown to scale as O( N
3) with the size of the system, with the memory requirements growing as O( N
2). The evaluation of the analytical gradient is significantly faster than the underlying SCF and CI calculations, so that
routine full geometry optimizations at the semiempirical CI level become possible for large systems.
Received: 24 April 1997 / Accepted: 10 June 1997 相似文献
12.
Instrumental neutron activation analysis (INAA) has been employed in the investigation of mass balance for mercury species
analysis in the analytical process. A new human hair reference material (IAEA-085) was analyzed for methylmercury using a
solid/liquid extraction procedure, with samples of extracts, residues, and untreated samples being analyzed by INAA. The certified
reference material NIES CRM No. 13, human hair, was analyzed in parallel. From the results obtained through the mass balance
studies, it was found that the extraction procedure was quantitatively complete, and that there was no difference between
the mass balance of Hg and the total Hg in the untreated materials. 相似文献
13.
Zr-2.5 wt% Nb has been found to be better compared to Zircaloy-2 as coolant tube material in Canadu-PHW reactors but has a stringent specification of less than 0.5 mg/kg of chlorine. Instrumental neutron activation analysis (INAA) for the determination of chlorine in Zr-2.5 wt% Nb is not possible because of the high activity produced due to the determination of the matrix. Hence a radiochemical neutron activation analysis (RNAA) procedure has been developed for the determination of chlorine in this material. For the first time the chlorine determination at less than a ppm level by NAA is being reported in this paper, in a number of Zr-2.5 wt% Nb samples ranging from 0.1 to 2 mg/kg. 相似文献
14.
Instrumental neutron activation analysis (INAA) and prompt gamma neutron activation analysis (PGAA) were used to characterize
a variety of single-wall carbon nanotube (SWCNT) materials from different principal production processes, as well as a material
containing SWCNTs together with other carbon species, catalyst residues, and trace element contaminants to be issued by the
National Institute of Standards and Technology for characterization and distribution as Standard Reference Material SRM 2483
Carbon Nanotube Soot. INAA proved to be well suited for the direct determination of catalyst and contaminant trace elements
requiring only minimal sample preparation. PGAA complemented the INAA data in particular with determinations of the light
elements. Carbon and hydrogen results provided information on the materials purity and storage properties. Strategies for
the quality assurance of the measurements in these new materials were developed. INAA and PGAA data were provided for the
value assignment of mass fractions of catalyst and trace elements in the candidate SRM and a systematic overview was obtained
of the catalyst and trace element contaminants associated with each of the major production routes. 相似文献
15.
Electrospray mass spectrometry (ESI-MS) is an established method for the qualitative analysis of synthetic peptide libraries
and combinatorial mixtures or collections of small organic compounds. However, the calculation of the mass distribution of
even small peptide mixtures is a time-consuming and error-proned task. Therefore, the computer program MS-Pep has been developed,
which calculates the masses of expected peptides, byproducts and the mass distributions of peptide libraries.
Received: 2 December 1996 / Revised: 17 April 1997 / Accepted: 21 April 1997 相似文献
16.
Analyses for certification have been made for the determination of 30 elements in the National Institute of Standards and Technology (NIST) Tomato Leaves renewal reference material, SRM 1573a. Three of the analytical techniques used were instrumental neutron activation analysis (INAA), radiochemical neutron activation analysis (RNAA), and prompt gamma activation analysis (PGAA). These techniques provided data on 19 elements by INAA, 10 elements by PGAA, and 7 elements by RNAA, with some overlap between techniques. For example, INAA was able to obtain overall analytical uncerainties (at the 95% confidence level) averaging ±2.2% for major and minor constituents (Ca, Mg, K), ±3.3% for constituents from 1 to 1000 g/g (Na, Fe, Al, Mn, Ba, Zn, Rb, La, Cr), and ±6.4% for elements between 10 and 1000 ng/g (Co, V, Se, Th, Sc, Sb), using sample dry weights of approximately 150 mg. These analyses represent the most extensive use to date of nuclear analytical techniques in the certification of a trace element SRM at NIST. 相似文献
17.
Six extraction methods for the analysis of PCBs (CB-28, CB-52, CB-101, CB-118, CB-138, CB-153 and CB-180) in sewage sludge
were tested. A certified reference material (CRM 392) was used for the evaluation of the performance of the methods. Soxhlet-Dean-Starch
with toluene as solvent, Soxhlet with hexane:acetone (2:3), cold digestion/saponification with 2 mol/L KOH in methanol followed
by partition with hexane, and sonicated liquid-solid extraction with hexane:acetone (1:1) produced accurate results (97%,
93%, 104%, and 88%, respectively) with acceptable precisions (6.2%, 6.8%, 15% and 12%, respectively). Results in close agreement
with the certified value for all congeners were obtained by treatment with BF 3-methanol prior to partition with dichloromethane. However, this is a tedious procedure and involves the use of hazardous
compounds. Cyclic steam distillation produced results with an accuracy of around 80% and a good precision (5.2%). The very
low consumption of solvents and other expensive chemicals by this technique and the possibility of analyzing the extract directly
without clean-up make it an interesting alternative to the more sophisticated methods. Column elution with dichloromethane
was found to be less efficient (61%), but it is a rapid, direct method with a low consumption of solvents and it may therefore
serve as screening method.
Received: 29 April 1997 / Revised: 30 July 1997 / Accepted: 6 August 1997 相似文献
18.
Six extraction methods for the analysis of PCBs (CB-28, CB-52, CB-101, CB-118, CB-138, CB-153 and CB-180) in sewage sludge
were tested. A certified reference material (CRM 392) was used for the evaluation of the performance of the methods. Soxhlet-Dean-Starch
with toluene as solvent, Soxhlet with hexane:acetone (2:3), cold digestion/saponification with 2 mol/L KOH in methanol followed
by partition with hexane, and sonicated liquid-solid extraction with hexane:acetone (1:1) produced accurate results (97%,
93%, 104%, and 88%, respectively) with acceptable precisions (6.2%, 6.8%, 15% and 12%, respectively). Results in close agreement
with the certified value for all congeners were obtained by treatment with BF 3-methanol prior to partition with dichloromethane. However, this is a tedious procedure and involves the use of hazardous
compounds. Cyclic steam distillation produced results with an accuracy of around 80% and a good precision (5.2%). The very
low consumption of solvents and other expensive chemicals by this technique and the possibility of analyzing the extract directly
without clean-up make it an interesting alternative to the more sophisticated methods. Column elution with dichloromethane
was found to be less efficient (61%), but it is a rapid, direct method with a low consumption of solvents and it may therefore
serve as screening method.
Received: 29 April 1997 / Revised: 30 July 1997 / Accepted: 6 August 1997 相似文献
19.
The adsorption and accumulation of NADH and the Cu 2+-NADH system at the mercury electrode surface was examined using differential pulse cathodic stripping voltammetry (DPCSV).
The method was developed for analytical trace determination of NADH. Experimental and operational parameters for the quantitative
determination of NADH were optimized and the detection limit was found to be 9.960 × 10 –8 mol/L. The effect of some interferences (e.g. purine compounds, amino acids and some metal ions) was considered.
Received: 3 January 1997 / Revised: 1 April 1997 / Accepted: 4 April 1997 相似文献
20.
The adsorption and accumulation of NADH and the Cu 2+-NADH system at the mercury electrode surface was examined using differential pulse cathodic stripping voltammetry (DPCSV).
The method was developed for analytical trace determination of NADH. Experimental and operational parameters for the quantitative
determination of NADH were optimized and the detection limit was found to be 9.960 × 10 –8 mol/L. The effect of some interferences (e.g. purine compounds, amino acids and some metal ions) was considered.
Received: 3 January 1997 / Revised: 1 April 1997 / Accepted: 4 April 1997 相似文献
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