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1.
Stefan Woelfl Margarete Mages Francisco Encina Francisco Bravo 《Mikrochimica acta》2006,154(3-4):261-268
The trace element content of individual copepod specimens and of the Brazilian water weed (Egeria densa) from a metal-contaminated wetland in Southern Chile were determined using total reflection X-ray fluorescence spectrometry.
Sampling of the water and the organisms was carried out at three sampling sites during 2004. Enhanced concentrations of dissolved
Fe and Mn were found in the column water and in the pore water. The Fe content in the benthic copepods was significantly elevated
compared to other aquatic organisms from different Chilean lakes. Regarding E. densa, healthy (green coloured) plants showed mass fractions of Fe, Mn, Ni, Cu and Zn which were typical for uncontaminated systems.
In contrast, damaged (brownish coloured) plants exhibited very high Fe and Mn concentrations indicative of contamination or
processes which changed the element load from the environment to the plant. 相似文献
2.
3.
Cornelia Weiss Joachim Knoth Heinrich Schwenke Holm Geisler Jürgen Lerche Rüdiger Schulz Hans-Jürgen Ullrich 《Mikrochimica acta》2000,133(1-4):65-68
The actual detection limits of total reflection X-ray fluorescence (TXRF) are determined and compared to those of destructive
physical analytical methods like secondary ion mass spectrometry (SIMS) and chemical methods like vapour phase decomposition
in combination with inductively coupled plasma-mass spectrometry (VPD-ICP-MS). The elements Ca, Ti, Cr, Fe, Cu were analyzed
on a Si wafer with 10 nm thermal oxide using TXRF and VPD-ICP-MS. The deviation of the TXRF and the VPD-ICP-MS results is
less than 30%. The thickness, composition and density of a Co/Ti two-layer stack were determined using angle dependent total
reflection and grazing incidence X-ray fluorescence (A-TXRF). The obtained data were compared with X-ray reflectometry (XRR)
and energy filtered transmission electron microscopy (EFTEM). The agreement between TEM and A-TXRF is excellent for the determination
of the thickness of the metal layers. From these results we conclude, that A-TXRF permits the accurate determination of composition,
thickness and density of thin metallic layers.
The results are discussed regarding detection efficiency, acquisition time, accuracy and reproducibility. 相似文献
4.
Microscopic X-ray fluorescence (MXRF) analysis was used to investigate different samples: meteorites, Jasper, coated glas
and, reference materials. The element distribution within sections of two different meteorites have been determined – one
metal rich and one oxide rich. The metal rich showed a matrix of Fe with Ni-, Ti-, and Si-enriched regions. The oxide rich
also showed a Fe rich matrix and regions with different concentrations of other elements. A reference sample with a flat and
polished but systematically tilted surface was used to assure, that roughness of the sections of the meteorites has only negligible
influence. Nondestructive investigations in Jasper with included Stromatolithes, which were fossilized more than 2 billion
years ago, showed the Stromatolithes to have Fe as main element instead of Si in the Jasper matrix. The thickness of Yb-layers
on glas was determined from the intensity of the Yb fluorescence peak. Calibration was done by using a sample without coating
and a reference sample whose thickness of the layer was determined by XRD reflectometry. Futhermore it has been shown that
materials can be analysed even if mounted in glas capillaries or covered by plastic foils. By using Mark capillaries the elements
from S to U may be detected instead of Na to U while working in vacuum mode. 相似文献
5.
Dale Newbury David Wollman Sae Woo Nam Gene Hilton Kent Irwin John Small John Martinis 《Mikrochimica acta》2002,138(3-4):265-274
Analytical X-ray spectrometry for electron beam instruments has advanced significantly with the development of the microcalorimeter
energy dispersive X-ray spectrometer (μcal EDS). The μcal EDS operates by measuring the temperature rise when a single photon
is absorbed in a metal target. A cryoelectronic circuit with electrothermal feedback and a superconducting transition edge
sensor serves as the thermometer. Spectral resolution approaching 4.5 eV for high energy photons (6000 eV) and 2 eV for low
energy photons below 2000 eV has been demonstrated in energy dispersive operation across a photon energy range from 250 eV
to 8 keV. Spectra of a variety of materials demonstrate the power of the μcal EDS to solve practical problems while operating
on a scanning electron microscope platform. 相似文献
6.
P. Wobrauschek C. Streli P. Kregsamer F. Meirer C. Jokubonis A. Markowicz D. Wegrzynek E. Chinea-Cano 《Spectrochimica Acta Part B: Atomic Spectroscopy》2008
Based on the design of the low cost Total Reflection X-Ray Fluorescence attachment module available since 1986 from Atominstitut (WOBRAUSCHEK-module) which can be attached to existing X-ray equipment, a new version was developed which allows the analysis of samples in vacuum. This design was in particular possible as the Peltier cooled light weight Silicon Drift Detector is following all adjustment procedures for total reflection as angle rotation and linear motion. The detector is mounted through a vacuum feed and O-ring tightening to the small vacuum chamber. The standard 30 mm round quartz, Si-wafer or Plexiglas reflectors are used to carry the samples. The reflectors are placed on the reference plane with the dried sample down looking facing in about 0.5 mm distance the up looking detector window. The reflectors are resting on 3 steel balls defining precisely the reference plane for the adjustment procedure. As the rotation axis of the module is in the plane of the reflector surface, angle dependent experiments can be made to distinguish between film and particulate type contamination of samples. Operating with a Mo anode at 50 kV and 40 mA with a closely attached multilayer monochromator and using a 10 mm2 KETEK silicon drift detector with 8 μm Be window, a sensitivity of 70 cps/ng for Rb was measured and detection limits of 2 pg were obtained. 相似文献
7.
A combined approach for the simultaneous determination of lanthanum, cerium, praseodymium, neodymium, and samarium in mineral water in the range from?·?10?2 to 101?µg/L by total reflection X-ray fluorescence analysis is reported. The combined technique of preconcentration of the rare earth elements ions includes the codeposition of their hydroxides on a collector and dispersive liquid–liquid microextraction by chloroform to form complexes with 1-(2-pyridylazo)-2-naphthol. The results for the determination of lanthanum and light lanthanides in natural water samples with the combined approach are in good agreement with measurements obtained by inductively coupled plasma–mass spectrometry. 相似文献
8.
Juha K. Vilhunen Alex von Bohlen Martina Schmeling Leena Rantanen Seppo Mikkonen Reinhold Klockenkämper Dieter Klockow 《Mikrochimica acta》1999,131(3-4):219-223
Particulate matter of Diesel emissions collected from diluted exhaust during standard test runs with two Diesel fuels of
different sulfur content was analysed by total-reflection X-ray fluorescence (TXRF). The trace elements determined were S,
Ca, Cr, Mn, Fe, Ni, Cu, Zn and Pb. Additionally, some filter materials were tested with respect to their applicability for
sample collection. Quartz fibre filters were found to be most suitable, both from a technical and a chemical point of view.
A clear reduction of total particulate emissions during the whole test was observed when the fuel with very low sulfur content
was used. In addition, it was found that the wear metal content of particulate matter emitted by a cold engine was higher
than that observed during normal engine working temperature.
Received September 10, 1998. Revision March 2, 1999 相似文献
9.
Austrian medieval silver/copper coins were investigated at their surfaces by energy dispersive X-ray fluorescence analysis
(EDXRF) and at the cross-sections by X-ray microanalysis in the scanning electron microscope (SEM/EDX) in order to estimate
the error occurring when corroded objects of art and archaeology are analyzed on the surface by non-destructive methods. Additionally,
Ag/Cu-standards were treated in diluted sulphuric acid and the depletion of copper on the surface was measured by EDXRF. By
calculating the ratio of the Ag-K/Ag-L intensity the process of blanching could be studied. 相似文献
10.
The fluorometric determination of periodate with tetraiodofluorescein has been developed. Under the optimum conditions responses
were linear between 4.0×10−7 ∼ 1.0 × 10−5 mol/L of periodate. The detection limit was 1.0 × 10−7 mol/L corresponding to a signal to noise ratio of 2. The proposed method was applied to the determination of periodate in
artificial fresh water and kelp sample with good results.
Received March 20, 2001 Revision December 19, 2001 相似文献
11.
This paper is the study of the fluorescence enhancement of Eu3+-1-ethyl-6-fluoro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridin-3-carbonic acid (enoxacin, EFLX) system by surfactants. It was
found that sodium dodecylbenzenesulfonate (SDBS) exhibits great enhancement on the fluorescence of the Eu-EFLX system. The
molar ratio is 1:2:1 for Eu:EFLX: SDBS. Under the optimum conditions, the fluorescence intensity is a linear function of europium
in the range of 1.0 × 10−8 ∼ 5.0 × 10−6 mol/L, the detection limit is 1.0 × 10−9 mol/L. The application of the Eu-EFLX-SDBS system for the determination of trace europium in rare earth samples gave satisfactory
results.
Received October 19, 2000. Revision August 10, 2001. 相似文献
12.
Steel is a very complex material, and nowadays all types of microbeam techniques are used to characterise it. This paper
describes how and why microbeam techniques are used in the steel industry, with special emphasis on micro-analysis of precipitates
and surface analysis. 相似文献
13.
Various kinds of precipitates can influence the mechanical properties of Ti-stabilized steels. The qualitative composition
of the Ti inclusions can be characterized microscopically, whereas for quantitative information to be obtained time-consuming
selective dissolution must be used. The present study aims at chemical speciation of the isolated precipitates as a solid
phase with the help of soft-X-ray spectrometry. Whether the method is capable of giving both qualitative and quantitative
information on the composition of Ti-mixtures is discussed. The precipitates in Ti-stabilized steels are investigated after
chemical dissolution of the steel matrix with a bromine/methanol mixture (1:10). By combination of soft-X-ray spectrometry
with X-ray fluorescence (XRF) and scanning electron microscopy (SEM) both qualitative and quantitative characterization of
the precipitates can be performed. They were found to consist mainly of TiC and TiN.
Received July 1, 1998. Revision December 29, 1998. 相似文献
14.
Christiane Bonnelle 《Mikrochimica acta》2002,138(3-4):275-282
The possibilities presented by low-energy electron-induced X-ray emission spectroscopy to study chemical interactions in
solids are discussed. Examples of change observed for the emissions between core levels as a function of the chemical environment
of the emitting atoms are given. By comparing the partial densities of the valence states associated to each type of atoms
in the compound, it is shown that the strength of the metal-ligand interactions can be obtained. Information on the charge
densities around each type of atoms can be deduced. Application to the study of the interactions at the atomic scale to solid–solid
interfaces is presented. 相似文献
15.
Sofia Pessanha Maria Luisa Carvalho Maria Becker Alex von Bohlen 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010
The purpose of this study is to determine the elemental content, namely heavy metals, of samples of vine-leaves, grapes must and wine. In order to assess the influence of the vineyard age on the elemental content throughout the several stages of wine production, elemental determinations of trace elements were made on products obtained from two vineyards aged 6 and 14 years from Douro region. The elemental content of vine-leaves and grapes was determined by Energy Dispersive X-Ray Fluorescence (EDXRF), while analysis of the must and wine was performed by Total Reflection X-ray Fluorescence (TXRF). 相似文献
16.
建立了微波消解前处理,全反射X射线荧光法(TXRF)同时测定松花粉中K、Ca、Ti、Mn、Fe、Ni、Cu、Zn和Rb9种生命元素含量的分析方法.松花粉原料经过微波消解前处理后,采用全反射X射线荧光光谱净计数、QXAS分析软件解谱和单一内标法进行定量分析.比较了干灰化法、湿消解法和微波消解法3种前处理方法的效果,并确立微波消解法作为样品前处理方法.用微波消解- TXRF法测定了花粉标准物质中的上述9种元素,并计算得到其仪器检出限(LLD)为0.002~0.054 mg/L,方法检出限(LDM)为0.004~0.122 mg/kg.TXRF法测定各元素的相对标准偏差(RSDs)为1.0%~5.5%.该方法操作简单、样品用量少、检出限低,对实际样品松花粉的测定结果与ICP - MS法无显著性差异. 相似文献
17.
The main objective of our work was to investigate the possibility and usefulness of indirect methods in X-ray microanalysis
for the quantification of biologically important compounds. Metallothionein-like proteins (MT-like proteins) from kidney and
liver, rich in sulfur were chosen as an indicator of heavy metal presence in cells and their environment. Tissues from goldfish
(Carassius auratus gibelio) were sampled after short and prolonged periods of exposure to Co+2, CrO4
−2, Pb+2, Cu+2 and control treatment and prepared for histochemical staining for peroxidated thiolate groups. Commonly used –S–S– bonds
dye (Nitro Red) was replaced with iodine atoms and they were quantified at L line by means of X-ray microanalysis combined
with SEM. After fish treatments with heavy metal solutions changes in MT-like proteins and in I atom contents were expected.
There was statistically significant decrease in MT-like proteins level in kidney after lead treatment (Pb/C = 0.62). In liver
a statistically significant increase in MT-like proteins concentration was observed after chromium, cobalt and lead ions treatment
in comparison to control animals. The following ratios were noted: 3.04 for Cr/C, 2.18 for Co/C and 2.10 for Pb/C. Our finding
indicates that the method of indirect measurement of MT-like proteins in fish and other animal tissues is possible. The concentration
of iodine atoms is above their detection level by EDS and their changes are possible to identify. During histochemical procedures
it is worth taking into account sample preparation methods which might disturb the quality and quantity of the analysed material. 相似文献
18.
Ian Barkshire Peter Karduck Werner P. Rehbach Silvia Richter 《Mikrochimica acta》2000,132(2-4):113-128
Performing X-ray microanalysis at beam energies lower than those conventionally used (< 10 keV) is known to significantly
improve the spatial resolution for compositional analysis. However, the reduction in the beam energy which reduces the X-ray
interaction diameter also introduces analytical difficulties and constraints which can diminish the overall analytical performance.
This paper critically assesses the capabilities and limitations of performing low beam energy, high spatial resolution X-ray
microanalysis. The actual improvement in the spatial resolution and the reduction in the X-ray yield are explored as the beam
energy is reduced. The consequences for spectral interpretation, quantitative analysis and imaging due to the lower X-ray
yield and the increased occurrence of X-ray line overlaps are discussed in the context of currently available instrumentation. 相似文献
19.
In this paper the effect of limestone, fly ash, slag and natural pozzolana on the cement hydration products is studied. Four
composite cements containing limestone, natural pozzolana from the Milos Island, slag and fly ash have been produced by intergrinding
clinker (85%), the above main constituent (15%) and gypsum. The grinding process was designed in order to produce cements
of the same 28d compressive strength. The hydrated products, formed after 1–28 days, were studied by means of X-ray diffraction.
Unhydrated calcium silicate compounds of clinker and hydration products such as C*H, C*S*H and ettringite are clearly observed.
Although there is not significant differentiation among samples hydrated for the same period of time, modifications of calcium
aluminate hydrates as well as sulfoaluminate hydrates, are indicated by the XRD patterns. In samples of limestone cement,
monocarboaluminate is formed in the first 24 hours and is still present after 28 days. 相似文献
20.
《Analytical letters》2012,45(5):953-962
Abstract Infrared spectroscopy and total reflection X-ray fluorescence spectrometry are used for the analysis of historical varnishes. Total reflection X-ray fluorescence spectrometry is used in the analysis of the elemental composition; infrared spectroscopy is used to determine the inorganic and organic molecules of the binding media, pigments and additives. On historical violins made by A. Guarneri and L. Widhalm silicon and tin were found by total reflection X-ray fluorescence spectrometry. Silicon was proved to be present in the form of silicon rubber by infrared spectroscopy. A further experiment confirmed that the treatment of a violin with silicon rubber casting material is detectable. 相似文献