Solving of some environmental pollution problems by X-ray fluorescence analysis

Application of Energy Dispersive X-Ray Fluorescence Analysis for environmental pollution control is described. The paper gives details of both sampling and measurement procedures for air particulates and plant samples. Usability of the method is shown on some examples typical in for environment protection practice. For instance with simultaneous sampling of air in more than one place, one can identify the polluting source and determine the contribution of this source to the total level of local pollution as well. It is possible with the EDXRF to investigate short and long-term concentration variations of metals in air including the distance factor too. Analysis of plant samples was performed in order to evaluate the contribution of automotive traffic to environmental pollution in areas of national parks. Examples of application of the method described in the paper give evidence in favour of the EDXRF as a good tool for investigation of environmental pollution.     

X射线荧光光谱分析

本文评述了我国在2002年7月～2004年6月间X射线荧光光谱, 包括粒子激发的X射线光谱的发展和应用, 内容包括仪器的研制、维护和维修、样品制备技术、 X射线荧光光谱基础研究、谱处理、分析方法研究和应用.     

X-ray fluorescence spectrometry applied to the analysis of environmental samples

X-ray fluorescence spectrometry is an expanding technique in the field of environmental analysis for both air and water pollution studies. Its capabilities now include the determination of gaseous contaminants in air in addition to the established area of elemental analysis, covering airborn particulates and soluble trace elements in water.     

X射线荧光光谱分析

本文评述了我国在2005年至2006年X射线荧光光谱,包括粒子激发的X射线光谱的发展和应用,内容包括仪器研制、激发源、探测器、软件、仪器改造、仪器维护和维修、样品制备技术、分析方法研究和应用.     

X射线荧光光光谱分析

评述了我国在2007～2008年X射线荧光光谱,包括质子激发的X射线光谱的发展和应用,内容包括仪器、软件、仪器改造、仪器维护和维修、基础研究和分析方法研究及其应用.     

Application of total-reflection X-ray fluorescence spectrometry in material analysis

X-ray fluorescence spectrometry with total reflection conditions is applied in the qualitative and quantitative determination of impurities in thin layers of Ti, TiO₂, and HfO₂ prepared by evaporation and of SiO₂, TiO₂, and Ta₂O₅ prepared by ion beam sputtering. The same method is used to examine stainless steel discs, which have to be used as reference materials,Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

Use of total-reflection X-ray fluorescence in search of a biomonitor for environmental pollution in Vietnam

The concentration of trace elements in tissues of several animals collected in the Ha Nam province, approximately 40 km south of Hanoi, Vietnam, has been investigated using total-reflection X-ray fluorescence analysis. We find that the freshwater mussel is probably the optimal choice of biomonitor for the pollution situation in Vietnam, but the freshwater crab, the toad and the catfish are also good candidates. The krait is probably also well suited for this purpose. It is shown that since several elements show a more or less pronounced accumulation tendency in a particular tissue it can be of great use to determine the levels in different tissues. When selecting an organism to be used as a biomonitor, other factors besides the mere concentration of trace elements must be considered, for instance the abundance and feeding habits.     

Quantification in grazing-emission X-ray fluorescence spectrometry

In grazing-emission X-ray fluorescence (GEXRF) spectrometry wavelength-dispersive detection can be applied. Much softer radiation and hence lighter elements than in total-reflection X-ray (TXRF) spectrometry can thus be detected. We used simulations to investigate methods of quantification of GEXRF results involving soft characteristic radiation. From these studies, it is concluded that for ultra-thin layers, e.g. the sub-monolayer amounts encountered in semiconductor contamination analysis, calibration plots are linear. For thicker layers, quantification should be performed very carefully because of deviations from linearity due to absorption of radiation and to oscillations in the calibration curve. These oscillations are caused by interference of fluorescence radiation emitted directly towards the detector and radiation reflected at the sample–substrate interface. Suggestions for a judicious choice of measurement conditions are made and the benefits of internal standardisation are discussed.     

X-ray fluorescence spectrometry of copper intermediates

Iron, magnetite, copper, copper(II) oxide, calcium carbonate, sulphur, silicon dioxide and aluminium oxide as components of copper intermediates (concentrates, slags, mattes, calcines and fluxes) in powdered (300-400 mesh) binary mixtures obey the Lachance-Traill equation, so the coefficients alpha(AX) of interelement effects can easily be determined experimentally. They show a reasonable agreement with the theoretical values calculated from mass absorption coefficients. This fact can be the basis of a convenient routine method for the determination of intermediates. Since the intermediates exhibit differences in the distribution of their atoms (microcosmic inhomogeneity) a correction factor k(dist) has to be used. Its value for the main components (concentrations > 5%) is in the range 0.92-1.24 The highest relative average deviation of the results from those of the classical "wet" methods is 2.7% for the major and 30% for the minor components.     

X-ray fluorescence spectrometry with synchrotron radiation

X-ray fluorescence spectrometry (x.r.f.) can be done through excitation with synchrotron radiation. This permits multi-element determinations in the trace region with improved detection limits compared to conventional x.r.f. Detection limits are evaluated and compared with theoretically calculated values. For a beam diameter of 0.5 mm and a sample of 1 mg cm^?2, absolute detection limits are between 0.1 and 0.4 pg. The dependence of the detection limit on the atomic number is reduced, when white synchrotron radiation is used for excitation instead of monochromatic radiation. The optimum of the limit of detection on the Z-scale can be shifted to higher atomic numbers and improved through filtration of the primary radiation by aluminium absorbers. Preparation of samples on different polymeric films is discussed in relation to blank values.     

X射线荧光光谱理论强度计算中激发因子的选择

激发因子是X射线荧光强度理论计算中的重要参数。对目前常用的四种激发因子算法进行了较为详细的比较,并设计了一种评价激发因子算法的实验方法,即用人工合成试样测定了八对能量接近的X射线特征谱线的强度比,然后根据不同的激发因子算法用理论方法计算出这些谱线对的强度比值,以两者的接近程度来判断这四种激发因子算法的适用性。结果表明,使用NRLXRF程序修改版中的激发因子算法计算出来的理论强度比与实测值之间的相对偏差最小。     

Application of total reflection X-ray fluorescence spectrometry for multi-elements characterization in human hair

Biomonitoring of Cr, Fe, Ni, Cu, Zn and Pb in scalp hair of the rural population in Punjab state of India was carried out using TXRF. The objective of the study was to understand their exposure to the trace elements from the local environment. The volunteers having age group 30–45 years were selected from rural region of Punjab. Validity of method was checked by analyzing Certified Reference Materials IAEA-436 and INCT-MPH-2. The results of trace elements analysis in hair samples shows no environmental gradient in the concentration of the elements like Cr, Fe, Ni, Cu, Zn however Pb was observed higher in few volunteers as compared to published value of concentrations in volunteers from Delhi.     

Application of total reflection X-ray fluorescence spectrometry to small glass fragments.

Total reflection X-ray fluorescence spectrometry (TXRF) has been applied for trace elemental analysis of small glass fragments. A small glass sample (a fragment with weight less than 0.5 mg) was decomposed by 100 microg of HF/HNO3 acid; the material was condensed to 10 microl and was dried on a Si wafer. Since the size of the dried residue on the Si wafer was less than 1 cm in diameter, an incident X-ray beam with about 1 cm in width could effectively excite elemental components in such a small glass fragment. The precision of the present technique was checked by analyzing the glass fragments (<0.5 mg) from NIST SRM612; the relative standard deviations (RSD) of less than 8.1% were achieved for elemental ratios that were normalized by Sr. Fragments (<0.5 mg) obtained from 23 figured sheet glasses were used as samples for estimating the utility of this technique to forensic discrimination. Comparison of five elemental ratios of Ti/Sr, Mn/Sr, Zn/Sr, Rb/Sr, and Pb/Sr calculated from X-ray fluorescence spectra was effective in distinguishing glass fragments that could not be differentiated by their refractive indexes (RI).     

Trends in environmental science using microscopic X-ray fluorescence

Microscopic X-ray fluorescence (micro-XRF) is a versatile tool in environmental analysis. We review work done in this field from 2008 to 2010 and highlight new aspects. Overall, there is a strong trend to combine fluorescence data with other data like diffraction or absorption spectroscopy. Also, the use of laboratory based instrumentation has become wide spread as more commercial instruments are available. At laboratories and synchrotron sites the trend towards higher spatial resolution is still persistent hitting sub micrometer values in case of synchrotron set ups.     

Monitoring of the environmental pollution by trace element analysis in tree-rings using synchrotron radiation total reflection X-ray fluorescence

This paper aims to study the environmental pollution in the tree development, in order to evaluate its use as bioindicator in urban and country sides. The sample collection was carried out in Piracicaba city, São Paulo State, which presents high level of environmental contamination in water, soil and air, due to industrial activities, vehicles combustion, sugar-cane leaves burning in the harvesting, etc. The species Caesalpinia peltophoroides (“Sibipiruna”) was selected because it is widely used in urban forestation. Synchrotron Radiation Total Reflection X-ray Fluorescence technique (SR-TXRF) was employed to identify and quantify the elements and metals of nutritional and toxicological importance in the wood samples. The analysis was performed in the Brazilian Synchrotron Light Source Laboratory, using a white beam for excitation and a Si(Li) detector for X-ray detection. In several samples, P, K, Ca, Ti, Fe, Sr, Ba and Pb were quantified. The K/Ca, K/P and Pb/Ca ratios were found to decrease towards the bark.     

Analysis of tungsten carbides by X-ray fluorescence spectrometry

Five sample presentation techniques were examined for the X-ray fluorescence spectrometric analysis of tungsten carbide alloys in powder and cemented forms. Powder samples may be oxidized by air at 600° before fusion (I), or preferably by lithium nitrate during fusion (II); the fusion is effected with lithium-lanthanum tetraborate followed by briquetting with graphite. Powder samples may also be blended with wax and briquetted (III). Cemented carbides are surface-prepared with silicon carbide before analysis (V). Briquettes prepared by blending carbide powder, lithium-lanthanum tetraborate and graphite (IV), give poor reproducibility, however, owing to micro-absorption effects the technique is not recommended. The determination of eight common elements in tungsten carbide is discussed and the relative standard deviations are 0.002–0.004 for major and 0.008–0.01 for minor elements.     

Energy dispersive X-ray fluorescence analysis of marine pollution indicators

The present work shows a methodology for the application of EDXRF with a X-ray tube, in the analysis of elements in the following matrices: microalgae, marine algae, marine sediments and corals. Various methods were applied: one using a relative external standard, a fundamental parameters method, an absolute method based on elemental sensitivity, a method which used X-ray fluorescence excitation measured in the back side of the sample for low contents heavy elements determination and a TRXRF method. The thin layer samples were prepared using a plastic resin. The analyzed samples of marine algae, marine sediments and corals belong to a marine ecosystem from the North of Havana City, the most affected area by natural metereological phenomena and human impact.     

Automated energy-dispersive X-ray fluorescence analysis of environmental samples

Summary A procedure is described for the routine automatic analysis of 20 elements in small environmental samples. Up to 50 samples a day can be processed. The instrument uses an energy dispersive X-ray spectrometer for the simultaneous detection of all elements during a 5–20 min measurement. Computer techniques are used for the subsequent data reduction of the X-ray spectra. The technique is applicable to air particulate matter filtered from the air, to suspended material in water which is filtered on a filter paper and to dissolved trace elements which are evaporated on filter paper or are collected on a thin ion-exchange loaded paper.

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Automatisierte energie-dispersive Röntgenfluorescenzanalyse von Umweltmaterial

Zusammenfassung Ein Verfahren zur automatischen Routinebestimmung von 20 Elementen in Umweltmaterial wird beschrieben. Bis zu 50 Proben je Tag können verarbeitet werden. Ein energie-dispersives Röntgenspektrometer wird zur simultanen Erfassung aller Elemente bei einer Messung von 5–20 min benutzt. Die nachfolgende Auswertung der Spektren wird mittels Computer durchgeführt. Das Verfahren findet Anwendung auf Schwebestaub oder in Wasser suspendierte Substanzen, die auf Filterpapier gesammelt wurden sowie auf gelöste Elementspuren, die auf Filterpapier getrocknet oder durch Ionenaustauschpapier angereichert wurden.

     

A modified standard addition method in X-ray fluorescence spectrometry

A modified standard addition method for single element determination by X-ray fluorescence spectrometry has been studied. The attenuation properties of the standard added samples are kept constant by adding decreasing amounts of an attenuation modifier along with increasing amounts of a standard. In this way the standard addition curve will be a straight line in cases where the ordinary standard addition curve is non-linear, and linear regression can be used to evaluate the concentration of the analyte. Standard additions of oxides of a number of elements, with and without modifier, have been made to cellulose powder or a mixture of aluminium oxide and polyethylene as matrices in order to test the method. The method has been applied to the determination of zinc in fly-ash from a steel work and of iron in cement. The fly-ash contained about 5% of zinc and the cement samples between 2 and 5% of Fe(2)O(3). The results were compared with those obtained by ICP-AES after decomposition of samples in lithium tetraborate or lithium metaborate and dissolution of the melt in 10%(v/v) nitric acid. The results agreed within 2%, relative, for fly-ash and within 3-6%, relative, for cement samples.     

Grazing-emission X-ray fluorescence spectrometry; principles and applications

In grazing-emission X-ray fluorescence spectrometry (GEXRF), the sample is irradiated at approximately normal incidence, and only that part of the fluorescence radiation is detected that is emitted at grazing angles. This configuration allows the use of wavelength-dispersive detection. This type of detection has the advantages of substantially better energy resolution at longer wavelengths (light elements, L and M lines of heavier elements) and a much larger dynamic range than the energy-dispersive detectors currently used in grazing X-ray techniques. Typical examples are presented of applications that are made possible by this new technique.