Use Of X-ray Fluorescence Spectrometry Research Articles

Spatializing soil elemental concentration as measured by X-ray fluorescence analysis using remote sensing data

Spatial soil information has significantly contributed to public policy and planning. The use of X-ray fluorescence spectrometry (XRF) in soil science, primarily in laboratory settings or for isolated point analyses, has been well documented. This study broadens the application of XRF data by integrating it with remote sensing data for a comprehensive understanding of soil patterns and processes. Focusing on a 2574 km2 area in Brazil, we utilized a lab-based XRF instrument to measure the total concentrations of key chemical elements in the soil, such as Al, Si, Ti, and Fe. These geochemical data were then spatialized using the digital soil mapping (DSM) framework. We employed a synthetic bare soil image and elevation data as covariates in the analysis. The spatial accuracy assessment yielded R2 values ranging from 0.65 to 0.81 for Fe, 0.62 to 0.78 for Ti, 0.52 to 0.63 for Si, and 0.48 to 0.63 for Al. The digital soil maps of geochemical elements aligned well with existing pedological, and geological maps as evaluated using multiple correspondence analysis. The integration of spatialized XRF data with DSM and remote sensing techniques shows significant promise in assessing soil variations across landscapes based on their chemical composition.

Energy dispersive X-ray fluorescence spectrometry characterization of wall mortars with principal component analysis: Phasing and ex situ versus in situ sampling

Mortared stone walls at the Coriglia, Castel Viscardo archaeological excavation site near Orvieto, Italy were analyzed via portable X-ray fluorescence (XRF) spectrometry to better understand their construction sequence and phasing. Data were collected ex situ for intact, ground, and fused bead samples and in situ at the site and evaluated through principal component analysis. Elements identified in the mortars included calcium, manganese, iron, nickel, zinc, rubidium, and strontium. Conclusions regarding wall associations agreed among the three ex situ sample forms, demonstrating that sample form does not matter when applying portable XRF spectrometry for mortar analysis. Conclusions drawn from the ex situ and in situ data and from visual observations by the site archaeologists also agreed and provides additional support for the use of XRF spectrometry for phasing of mortared walls. Lastly, this study demonstrates that in situ data collection for archaeological mortars is valid while also ensuring the preservation of cultural heritage objects.

On-site teaching with XRF and XRD: training the next generation of analytical X-ray professionals

There is a growing need for environmental scientists, geoscientists, and analysts skilled in the use of X-ray fluorescence spectrometry and X-ray diffractometry. The challenge for educators is how to inspire, teach, and make the next generation of professional X-ray users and analysts ready for employment. In this paper, we present vignettes from teaching applications of X-ray analytical techniques at three scaffolded levels, from senior high school students, undergraduate science students, to postgraduate researchers. At each of these levels the pedagogical complexity increases, from simple data use at high school, to observing how data are generated and being able to constrain analytical uncertainty at the undergraduate level, to generating high-quality data at the postgraduate level. In all cases, transportable equipment is used in on-site analytical programs to inform the experimental design, level of sampling required, and research outcomes.

The influence of using automated sample preparation and pressed powder pellets on data quality when analysing iron ore samples using XRFS techniques

The use of X-ray fluorescence spectrometry (XRFS) on fusion discs to determine Fe in iron ores provides high quality data and is widely used by iron ore producers, but is costly. This method of sample preparation eliminates mineral and particle size effects which can lead to biased results when using pressed powder pellets. For many applications, such as exploration and mining control, the method of the XRFS analysis of iron ores by pressed powder pellet probably provides data of adequate quality and this method is now used for most analyses by Kumba Iron Ore, an iron ore producer in South Africa. Automation of sample preparation procedures should improve the quality of data for Fe, K2O and P determined by XRFS using pressed powder pellets. This study was carried out by Kumba to compare the quality of data obtained using the three different sample preparation methods and using precision as the measurement of quality. The three methods were (i) automated sample preparation, measurement on fused discs, (ii) automated sample preparation, measurement of pressed powder pellets, and (iii) manual sample preparation, measurement of pressed powder pellets. It was found, as expected, that the precision was best for the measurements on fusion discs where automation was used for sample preparation procedures. The relative standard deviations (RSDs) for these for Fe, K2O and P were 0·074, 1·906 and 1·636% respectively. However, the XRFS data generated from the pressed powder pellets, where automation was used for sample preparation procedures, compare remarkably well against those from the auto-prepared fusion discs. The RSDs for Fe, K2O and P for these were 0·131, 2·912 and 1·989% respectively. As expected, the poorest quality data resulted from the XRFS measurements on pressed powder pellets where manual methods only were used for sample preparation. The RSDs for Fe, K2O and P for these were 0·194, 4·361 and 3·430% respectively. It is concluded that the analysis of iron ores by pressed powder pellet can produce acceptable quality analytical data for many applications. Also the introduction of automation for sample preparation in the iron ore analytical laboratory does improve the quality of data produced by this XRFS analytical method.

X-Ray Fluorescence Analysis of Valuable Metals

This paper reviews the use of X-ray fluorescence spectrometry (XRFS) for non-destructive studies of valuable metallic objects in the fields of jewelry, archaeology and art, as well as its application in the analysis of coatings and solutions, due to the interest of these issues in jewelry manufacture. The general features of the technique as well as the most outstanding results obtained in the commented fields are described, taking into account the most important sources of error, mainly in the case of samples that have suffered corrosion processes.

The use of X-ray fluorescence spectrometry for the analysis of plants, especially lichens, employed in biological monitoring

Several analytical techniques are available for the elemental analysis of plants such as lichens used in pollution monitoring studies. This paper examines the advantages and disadvantages of one technique, X-ray fluorescence spectrometry, for determining the elemental content of lichen. The technique can be used for macro nutrients such as K and Ca and for trace metals such as Cu, Pb and Zn as well as for non-metals, especially S. Consideration is given to collection, preparation and analytical procedures for lichens using this analytical method. Data from studies using XRF are presented. Improvements are suggested with regard to sample preparation, and the limitations which prevent the method being more widely adopted are reviewed. The new generation of computer-assisted spectrometers have significantly lowered detection limits, so that background elemental levels in remote areas as well as enhanced levels near industrial activities can effectively be assayed in lichen or other plant samples.

Combined use of X-ray fluorescence spectrometry and laser ablation inductively coupled plasma mass spectrometry in the analysis of soils

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Use of X-ray fluorescence spectrometry for the direct multi-element analysis of coal powders

The evaluation of automated X-ray fluorescence (XRF) spectrometry for the elemental analysis of UK coals is described. The XRF determination of chlorine is now used for coal pricing purposes and phosphorus levels are reported routinely in order to monitor the quality of coal. The data on elemental composition which can be generated rapidly by direct XRF analysis of pressed coal powders enable values of slagging and fouling indices to be determined with acceptable accuracy. Such factors have wide application in industry for predicting the combustion characteristics of coal, including slagging and fouling propensities. The relative standard deviations for the elements chlorine, sulphur and phosphorus and the calculated slagging index and fouling factor are less than 7%. The accuracy of the method when compared to standard reference coals is acceptable with detection limits which range from 0.04 and 0.05% m/m for the major elements Al and Si, respectively, 0.01% m/m for minor elements and 0.002% m/m for the trace element phosphorus.

Use of x-ray fluorescence spectrometry in ion-exchange studies of leach liquors

Equilibrium and kinetic studies of ion exchange of a complex leach liquor from coal ash, with strongly basic resins and a liquid ion exchanger are reported. The multi-component system was studied by determining the composition of the effluents and by non-destructive analysis of the loaded ion exchangers by XRF spectrometry. In the case of column operation, the elution processes were investigated by the same method, which was very appropriate for non-destructive monitoring of resin regeneration steps done repeatedly with the same resin sample.

Halothane Biotransformation in Anesthetists

Serum bromide levels were measured in 115 anesthetists by use of x-ray fluorescence spectrometry. Bromide levels peaked at 184 +/- 21 micron in anesthetists regularly exposed to halothane (n = 20), at 58 +/- 4 micron in anesthetists sporadically exposed to halothane (n = 71), and at 46 +/- 3 micron in nonexposed anesthetists (n = 24). Kinetic studies were carried out in five other anesthetists after ten days of exposure to halothane. Average daily halothane concentration was 19.2 +/- 3.2 ppm; duration of exposure was 3.8 +/- 0.2 hours/day. Mean serum bromide level increased from 40 +/- 4 micron before exposure to 220 +/- 36 micron on the last day of exposure. Serum bromide half-life was 14 +/- 1.7 days. The study demonstrates that anesthetists debrominate halothane in a dose-related fashion. Serum bromide levels achieved, however, were far below those reported to result in clinical bromism.

Halothane Biotransformation in Anesthetists

Serum bromide levels were measured in 115 anesthetists by use of x-ray fluorescence spectrometry. Bromide levels peaked at 184 +/- 21 micron in anesthetists regularly exposed to halothane (n = 20), at 58 +/- 4 micron in anesthetists sporadically exposed to halothane (n = 71), and at 46 +/- 3 micron in nonexposed anesthetists (n = 24). Kinetic studies were carried out in five other anesthetists after ten days of exposure to halothane. Average daily halothane concentration was 19.2 +/- 3.2 ppm; duration of exposure was 3.8 +/- 0.2 hours/day. Mean serum bromide level increased from 40 +/- 4 micron before exposure to 220 +/- 36 micron on the last day of exposure. Serum bromide half-life was 14 +/- 1.7 days. The study demonstrates that anesthetists debrominate halothane in a dose-related fashion. Serum bromide levels achieved, however, were far below those reported to result in clinical bromism.

Determination of organic and inorganic carbon in soils by potentiometry

A method is described for the direct, rapid and precise determination of 0–6 mg of organic and/or inorganic carbon in soils. The equivalent amount of carbon dioxide, liberated by improved combustion techniques, is absorbed and precipitated in a solution containing 2.50 mmol of sodium hydroxide and 0.96 mmol of barium chloride. Next, the resultant barium carbonate is dissolved by the addition of 0.99 mmol of EDTA (disodium salt). The pH of the final solution is related to the amount of carbon dioxide present by means of a calibration graph. By use of a pH meter with an expanded range of 1 pH unit, sensitivity to 10 µg of carbon is achieved. Analyses of pure organic compounds, such as benzoic acid and hydroquinone, show recoveries accurate to within 0.1 mg of carbon. Results for calcareous soils are in close agreement with values for calcium oxide obtained by use of X-ray fluorescence spectrometry.

Diffraction Effects in X-Ray Fluorescence Analysis of Semiconductor-Grade Silicon and other Monocrystalline Materials

The use of x-ray fluorescence spectrometry for the determination of doping elements in semiconductor materials appears to have been neglected, presumably because of its relative insensitivity, as compared to other techniques such as nuclear activation analysis and emission spectroscopy. However, in the case of silicon heavily doped with antimony or arsenic, it was felt that this insensitivity might not be a problem, especially in view of the low atomic number of the matrix and the availability of a vacuum x-ray spectrometer. Furthermore, x-ray fluorescence spectrometry would provide a very convenient means for the analysis of semiconductor silicon slices, cut from cylindrical rods of silicon, since specimens in this form would require little or no sample preparation.