Energy Dispersive X-ray Fluorescence Determination Research Articles

Energy dispersive X-ray fluorescence determination of uranium in different uranates using Rh Kα scattered peaks for matrix correction

Determination of uranium in different matrices and compounds is required for compositional analysis and material characterization of uranium based materials. In the present work, we have explored the possibility of utilising Rh Kα scattered peaks: Compton and Rayleigh, for minimizing the effect of matrix and determining uranium in different matrices using Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometry. The method was applied for determination of uranium in presence of Na, Zn, Rb, Bi and Th in solid samples presented in the form of compounds and mixtures. Different calibration plots were made for U in different matrices against the intensity of the scattered peaks. Different procedures of calibration were studied using both uranium Lα and Lβ as analytical lines. Sample specimens were presented in the form of fused bead as well as pressed pellets. The advantage of this method is that there is no need to add any standard in the samples. The analytical results of all the studies showed an average deviation of 3% between the EDXRF determined and the expected uranium concentrations and a RSD (Relative Standard Deviation) of 4% (1 s, n = 3).

Insights into the inter-element effects in the EDXRF determination of zirconium in binary aqueous solutions via the calibration method

Calibration of the energy dispersive X-ray fluorescence (EDXRF) spectrometer, using pure elemental standard solutions of Cu, Zr, Nb, Mo, Ta, and U, was carried out and the instrumental sensitivity was derived for each. The effects of the presence of the rest of these elements on the calibration of Zr were evaluated by analyzing the respective binary solutions, separately. All the matrix elements led to a reduction in the Zr- sensitivity of the spectrometer. Intercepts of the calibration curves were found to decrease with Cu, Mo. Nb, Ta, and U led to the elevation of the intercepts. The highest specific changes (per mg of the matrix) in both the slope and intercept were observed upon the addition of Mo. Numerically, these values were -5,917 and -1,187 respectively. Limits of detection for Zr, from the calibration curve, were the best (0.28 μg) in the presence of 7.8 mg Mo and the worst (165.4 μg) in the presence of 53 mg U. The results were validated by multiple standard additions on a sample and analysis of reference standard solution of Zr. Quality control sample analysis re-affirmed the accuracy of the present results. Repeatability was also established for the measurements of solution samples.

Determination of Cu, Ni, Mn, and Pb in diesel oil samples using reversed-phase vortex-assisted liquid-liquid microextraction associated with energy dispersive X-ray fluorescence spectrometry

A method was developed based on reversed-phase vortex-assisted liquid-liquid microextraction (RP-VALLME) combined with energy dispersive X-ray fluorescence (EDXRF) spectrometry for the determination of Cu, Mn, Ni, and Pb in diesel oil samples. In this procedure, a nitric acid solution was used as the extraction phase to isolate analytes from organic samples. After a centrifugation step, the aqueous phase was added dropwise to a filter paper disc for EDXRF determinations. The following variables were optimized: type of extraction phase solution, concentration of the extraction phase, stirring time, and sample volume. Some instrumental parameters were also evaluated: atmospheric condition, irradiation energy, and irradiation time. Using 100 μL of a 0.075 mol L−1 nitric acid solution as the extraction phase for a sample volume of 5.0 mL and a stirring time of 45 s, the limits of detection were 14, 8, 10, and 7 μg L−1 for Cu, Mn, Ni, and Pb, respectively. The enrichment factors obtained were 34 (Cu), 62 (Mn), 59 (Ni), and 64 (Pb). The precisions, expressed as relative standard deviations (RSDs, %), were calculated from ten replications of the experiment under optimized conditions using standard solutions containing 200 μg L−1 and 400 μg L−1 of all four analytes and ranged between 2.1 and 6.4%. The results of recovery tests ranged from 87 to 112%. The proposed procedure was efficiently applied to the determination of the four analytes in diesel oil samples. The results were compared with those obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) after sample digestion, and no significant differences were found.

English

This study focuses on energy dispersive X-ray fluorescence determination of minor and major elements in selected soils of Mambilla Plateau. The 12 sampled soil composites analysed were done by energy dispersive X-ray fluorescence technique for minor and major elements. The elemental oxides determined were Al2O3, CaO, K2O, TiO2, SiO2, BaO, Fe2O3, and MnO. The result obtained in the study showed that the general percentage concentration of elemental values were in decreased order of Si>Al>Ti>K>Ca for major elements and Fe>Mn>Ba minor elements accordingly. The major elements category showed silicon as the highest mean concentration at location S 84.09%±6.40 and calcium lower mean concentration with value of 0.32%±0.02. The minor elements concentration percentage revealed Fe with a mean value at location N 23.18%±3.1 being the highest and Ba is the lowest at location S 0.14%±0.1. The soil analysis revealed low concentration of essential major and minor elements, however, high concentration of Al and Fe that may solubilized at low pH and splitting H+ from water molecule showed increased soil acidity. Key words: Energy dispersive X-ray fluorescence (EDXRF), minor elements, major elements, percentage, Mambilla Plateau.

Determination of ash content of milk-based powders by Energy Dispersive X-ray Fluorescence

A simple and rapid method for the determination of ash content by Energy Dispersive X-Ray Fluorescence (ED-XRF) was established and validated for milk-based powders. ED-XRF determination can interestingly replace classical gravimetric methods by reducing the analytical time from several hours to three minutes only. Indeed the results obtained show that ED-XRF gives statistically comparable results to classical methods (furnace and thermo-gravimetric analyzer). The relative expanded uncertainty of the ED-XRF method was found to be <10%, which is acceptable.Using ED-XRF technique for ash content determination on top of elemental determination analyses allows to reduce delays and costs.

Multi-elemental ED-XRF Determination in Dehydrated Bouillon and Sauce Base Products

This work describes a quick and easy method for the quantification of a series of macroelements (Na, Mg, P, Cl, K, and Ca) and trace elements (Fe and Zn) by energy-dispersive X-ray fluorescence (ED-XRF). The method was developed and validated using commercial dehydrated bouillon and sauce base products. All samples were systematically powdered and analyzed by reference methods (i.e., potentiometry for chloride and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) for other elements) and by ED-XRF. A calibration set of 15 samples was selected to cover uniformly the concentration range of each element, and their reference method values were used to calibrate the ED-XRF device. A second validation set, composed of 26 additional samples, was then analyzed as though they were unknown samples. During this validation step, the elemental concentrations obtained by ED-XRF were systematically evaluated against those obtained from the reference methods. For the eight investigated elements, the ED-XRF method was found to be comparable to the reference one; furthermore, the bias between both methods was found to be not significantly different from 0. For the macroelements, the relative uncertainties RSD(u) were found to be lower than 20%. These results have demonstrated that ED-XRF is a quick and reliable method for the quantification of the listed elements in dehydrated bouillon and sauce base products. The capability to accurately measure trace elements (below 20 mg/kg), while also being able to measure a concentration of several tens of gram per 100 g of NaCl, makes ED-XRF a perfect tool to check the correct addition of premixes and also to ensure the correct claim of macroelements, respectively.

Evaluation of uncertainty in the energy dispersive X-ray fluorescence determination of platinum in alumina

Uncertainty, the most important characteristic of an analytical result, has been evaluated using a bottom-up approach during EDXRF determination of Pt in alumina. The calibration function of the EDXRF spectrometer was derived through bivariate least squares fitting, in combination with weighted regression of the residuals.

Energy Dispersive X-Ray Fluorescence Determination of Gallium in Aqueous Uranium Solution and (U-Ga) Mixed Oxide Powders

Energy Dispersive X-Ray Fluorescence Determination of Gallium in Aqueous Uranium Solution and (U-Ga) Mixed Oxide Powders

Feasibility of energy dispersive X-ray fluorescence determination of gold in soft tissue for clinical applications

The feasibility of using EDXRF for a rapid quantitative analysis of gold in tumor tissue has been investigated. The protocol described here demonstrates that sample biopsies can be analyzed in as little as 8 hours, with minimal sample preparation. Samples were prepared by drying a 35 μL aliquot of tissue dissolved in KOH in a standard EDXRF cup on a Prolene® support, producing a thin sample. Calibration curves of XRF peak intensity (CPS/mA) to the gold concentration (0-50 PPM) were prepared for liver, tumor, and a mix of tissue types. A linear regression demonstrated an R2 correlation of 0.93. Analysis of experimental samples showed that gold accumulation in tumors (5.8-41.3 PPM) was in agreement with previous studies, where samples were processed using INAA or ICP-MS. This report provides guidance for elemental analysis of gold in tissue in a shorter time span, showing potential for its use in a clinical setting.

Synchrotron‐induced EDXRF determination of uranium and thorium in mixed uranium–thorium oxide pellets

Uranium and thorium in their mixed oxides were determined by synchrotron‐induced energy dispersive X‐ray fluorescence (EDXRF) spectrometry. Mixed oxide calibration mixtures containing uranium and thorium in different relative amounts and approximately fixed amount of yttrium were prepared in the form of pellets. The EDXRF spectra of the pellets were measured at the microfocus XRF (BL‐16) beam line of Indus‐2 synchrotron radiation facility (Raja Ramanna Centre of Advanced Technology, Indore, India). Characteristic X‐ray lines U Lα, Th Lα, and Y Kα were used as analyte lines. Calibration plot for the determination of uranium was prepared by plotting amount ratios of U and Y against the intensity ratios of U Lα and Y Kα. Similarly, a calibration plot for thorium analysis was also made. The amounts of uranium and thorium in the sample mixtures prepared in similar way as the calibration mixtures were determined using the aforementioned calibration plots. The precision values obtained for uranium and thorium determinations were found to be 0.3 and 0.2% (relative standard deviation, 1σ), respectively. The EDXRF results deviated from the expected values by 1% for uranium and 0.9% for thorium determinations. These analytical features are much superior compared with laboratory‐based analysis results. Copyright © 2012 John Wiley &amp; Sons, Ltd.

A comparative study on determination of uranium and thorium in their mixed oxides by EDXRF using tube and radioisotope X‐ray sources

AbstractStudies on the matrix effects of uranium and thorium on the determinations of each other in their mixed oxides using energy dispersive X‐ray fluorescence (EDXRF) spectrometry with tube and radioisotope excitations of U Lα and Th Lα are reported. An internal standard method for the determination of uranium and thorium in these mixed oxides is found suitable. Comparison of the analytical results of EDXRF determinations of uranium and thorium using tube and radioisotope excitation sources has been made. The analytical methodology involves preparation of mixed oxide calibration/sample mixtures of uranium and thorium oxides, mixing of internal standard yttrium in these mixtures, pelletizing the mixtures after thorough mixing and grinding using boric acid binder and measuring EDXRF spectra of the specimens thus prepared using Rh X‐ray tube as well as 109Cd radioisotope source. The samples were analyzed for uranium and thorium on the basis of the calibration plots obtained by plotting the intensity ratios of the analyte and internal standard characteristic X‐ray lines and their corresponding amount ratios. An average precision of 1.2% (1 s RSD) was observed for the determination of U and Th and the results deviated from the corresponding expected values by 3% on average. Due to the refractory nature of thorium oxide, comparatively more grinding time was required for thorium determinations. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Energy dispersive X-Ray fluorescence determination of thorium in phosphoric acid solutions

Energy dispersive X-ray fluorescence studies on determination of thorium (in the range of 7 to 137 mg/mL) in phosphoric acid solutions obtained by dissolution of thoria in autoclave were made. Fixed amounts of Y internal standard solutions, after dilution with equal amount of phosphoric acid, were added to the calibration as well as sample solutions. Solution aliquots of approximately 2–5 µL were deposited on thick absorbent sheets to absorb the solutions and the sheets were presented for energy dispersive X-ray fluorescence measurements. A calibration plot was made between intensity ratios (Th Lα/Y Kα) against respective amounts of thorium in the calibration solutions. Thorium amounts in phosphoric acid samples were determined using their energy dispersive X-ray fluorescence spectra and the above calibration plot. The energy dispersive X-ray fluorescence results, thus obtained, were compared with the corresponding gamma ray spectrometry results and were found to be within average deviation of 2.6% from the respective gamma ray spectrometry values. The average precision obtained in energy dispersive X-ray fluorescence determinations was found to be 4% (1 σ). The energy dispersive X-ray fluorescence method has an advantage over gamma ray spectrometry for thorium determination as the amount of sample required and measurement time is far less compared to that required in gamma ray spectrometry.

Energy dispersive X-ray fluorescence determination of cadmium in uranium matrix using Cd Kα line excited by continuum

An energy dispersive X-ray fluorescence method for determination of cadmium (Cd) in uranium (U) matrix using continuum source of excitation was developed. Calibration and sample solutions of cadmium, with and without uranium were prepared by mixing different volumes of standard solutions of cadmium and uranyl nitrate, both prepared in suprapure nitric acid. The concentration of Cd in calibration solutions and samples was in the range of 6 to 90 µg/mL whereas the concentration of Cd with respect to U ranged from 90 to 700 µg/g of U. From the calibration solutions and samples containing uranium, the major matrix uranium was selectively extracted using 30% tri-n-butyl phosphate in dodecane. Fixed volumes (1.5 mL) of aqueous phases thus obtained were taken directly in specially designed in-house fabricated leak proof Perspex sample cells for the energy dispersive X-ray fluorescence measurements and calibration plots were made by plotting Cd Kα intensity against respective Cd concentration. For the calibration solutions not having uranium, the energy dispersive X-ray fluorescence spectra were measured without any extraction and Cd calibration plots were made accordingly. The results obtained showed a precision of 2% (1 σ) and the results deviated from the expected values by < 4% on average.

EDXRF determination of iron during infant cereals production and its fitness for purpose

SummaryThe objective of this study was to develop and validate a rapid and efficient method for the determination of iron in commercial infant cereals using energy‐dispersive X‐ray fluorescence (EDXRF) technique. Two EDXRF devices were tested: Spectro Xepos and PANalytical Minipal 2.20 samples were used for calibration of the XRF apparatus. The technique was validated using a second set of twenty other samples and comparing results of the reference method (inductively coupled plasma‐atomic emission spectroscopy, ICP‐AES) and those of the EDXRF. No significant bias was found between the two methods. Three pellets per sample are prepared under 10 tonnes of pressure and analysed. The total time of analysis for iron is less than 20 min and this technique appears to be adequate for process control during infant cereals production.

Determination of rubidium and strontium in silicate rocks by energy dispersive and wavelength dispersive X-ray fluorescence analysis: a comparative evaluation of precision

Levels of precision routinely attainable in the determination of Rb and Sr at trace abundances by energy dispersive X-ray fluorescence (EDXRF) analysis are reported and compared with results obtained by wavelength dispersive X-ray fluorescence (WDXRF) analysis. Surprisingly, the precision of EDXRF determinations is similar to that for WDXRF analysis at concentrations less than about 20 ppm. The favourable characteristics of EDXRF analysis at these low concentrations are attributed to the use of a primary beam filter which reduces backgrounds in the spectral region of these elements. At higher concentrations, the precision of WDXRF results becomes progressively better than EDXRF owing to the superior sensitivity of the technique. Above 50 ppm, the relative standard deviation of WDXRF results is less than 1%. The EDXRF technique achieves comparable levels of precision only above 100 ppm. The parallel acquisition of Rb and Sr data by the ED method appears to provide no advantage in minimizing errors in the Rb:Sr ratio for which the optimum precision is required by isotope geochemists for geochronology. The precision of WDXRF measurements can be further improved by longer or multiple counting, but this procedure would be inefficient in EDXRF analysis where routine count times are already long (about 1200 s). It is noted that representative sub-sampling may not always be achieved in rock samples routinely prepared for geochemical analysis. If the highest precision is required then it is preferable to count replicate samples rather than repeatedly counting the same sample. Any form of multiple counting would not be an efficient proposition by EDXRF.

Application of radioisotope excited energy dispersive X-ray fluorescence determination of palladium in catalysts and doped venezuelan laterites

A rapid procedure for determining palladium in catalysts and geoiogical materials is presented. This method involves the use of an241Am (100 mC) source for excitation and employs a PDP-11/05 processor for the data acquisition and analysis by energy-dispersive X-ray fluorescence. The relative standard deviation for 5 independent determinations is less than 3% for 100 seconds of fluorescent time. The calculated and measured values agreed well for both, the prepared standards and the doped Venezuelan laterites. Finally, data on the different sources of error is given including counting time, sample preparation, and total error.

Determination of silver in photographic materials by energy dispersive X-ray fluorescence analysis

Isotope excited energy-dispersive X-ray fluorescence determination of silver in photographic materials yields poor reproducibility because of difficulties in reproducing the geometry. By placing the film sample between the detector and the radioactive source this difficulty is overcome. The theory of such an arrangement indicates that effects due to varying thickness of film base or unequal coating in the case of double-coated film play a minor role. The suggested improvements in measuring geometry should be of value for any application in which samples are in the form of thin foils or sheets.