Capabilities of elemental analysis by EDXRF for geochemistry

Elemental analyses of 10 geological samples from Morocco and some Standard Reference Materials were performed by Energy Dispersion X-Rays Fluorescence, Wavelength Dispersion X-Rays Fluorescence and Neutron Activation Analysis techniques in order to assess the accuracy and sensitivity of the concentrations determined with regard to requirements in geochemical exploration. The possibilities of utilization of EDXRF as an appropriate and economic technique for the analysis of various elements which are important in interpretation of geochemical data were evaluated.     

Determination of elemental composition of aluminosilicate clays by EDXRF

Aluminosilicate clay samples were analyzed for the constituent elements with respect to a certified reference material using microcrystalline cellulose powder as a binder for presentation as a pressed pellet to an energy dispersive X-ray fluorescence spectrometer. Sample preparation for presentation is highlighted. The data manipulation to achieve the analytical accuracy from the inherent precision is discussed.     

Assessment of elemental contamination in the bottom sediments from a dam reservoir using a sequential extraction technique and chemometric analysis

The concentration of elements in sediments is an important aspect of the quality of water ecosystems. The element concentrations in bottom sediments from Goczalkowice Reservoir, Poland, were investigated to determine the levels, accumulation and distribution of elements; to understand the contamination and potential toxicity of elements; and to trace the possible source of pollution. Sediments were collected from 8 sampling points. The functional speciation, mobility and bioavailability of elements were evaluated by means of modified Tessier sequential extraction. The element contents were measured by optical emission spectrometry with inductively coupled plasma. The experimental results were analyzed using chemometric methods such as principal component analysis and cluster analysis to elucidate the metal distributions, correlations and associations. The highest concentrations of most elements were found at the center of the reservoir. The distribution of metals in the individual fractions was varied. To assess the extent of anthropogenic impact indices, contamination factor, degree of contamination, metal pollution index and risk assessment code were applied. The calculated factors showed the highest contamination factor and the ability of chromium to be released from sediments. The degree of contamination showed that the area is characterized by a very high contamination. Strontium and manganese showed high potential ecological risk for sediments.      

Determination of elemental composition of airborne dust and dust suspended in rain

To clarify the magnitude of wash-out effect of rain on the elemental composition of airborne dust and the possible origin of the dust, the dust samples were collected with a high-volume air sampler at the JAERI-Tokai. The dust suspended in rain was also collected from rain by filtration. Up to 20 elements in both types of the dust were determined by instrumental neutron activation analysis. It was found that the elements determined could be classified into 3 groups from the elemental composition and the elemental correlation in both types of the dust samples.     

State-of-the-art contamination control techniques for ultratrace elemental analysis

The detection limits of many nonnuclear methods for ultratrace (≤0.1 μg/g) elemental determinations lie well below the level at which precise and accurate practical analysis can be executed routinely. Advances in analytical methodologies which are rapidly eroding such disparities are reviewed. The applications of X-ray fluorescence, atomic absorption, stable isotope dilution mass spectrometry, and laser intracavity absorption spectrophotometry to ultratrace analyses not amenable to solution by nuclear methods are discussed.     

Development of EDXRF techniques for the quantitative multielement analysis of urban dust samples

Summary The investigation and monitoring of suspended particulate matter in air require accurate and sensitive multielement analysis of large numbers of samples. In the work described, airborne particles and settled urban dusts were examined by energy dispersive X-ray fluorescence spectrometry with secondary-target excitation. The practical requirements of trace-element determinations in dusts are reasonably satisfied by two techniques. Deposition of fine particles (under 3.5m) on Nucleopore membrane filters provides thin-film samples, for which absorption and particle-size effects are usually negligible. Calibration is achieved by sputtering of certified NBS standard glasses onto membrane filters. In the destructive fusion and direct solidification technique, sample inhomogeneities and particle-size effects are eliminated by fusing the sample with lithium borate in a Pt/Au alloy crucible. La₂O₃ or WO₃, added as heavy absorbers, can reduce the interelement-effects of the thick specimens to a certain extent. A newly developed computer program, based on a modified mathematical expression for the intensity, compensates for absorption and secondary fluorescence effects. It is demonstrated that for some trace elements the background can be easily predicted as a linear function of the incomplete charge-collection of the Si(Li) detector. An intermethod comparison with atomic-absorption results is presented; the results are verified with the NBS Fly Ash standard reference material.

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Zusammenfassung Die Untersuchung und Überwachung luftgetragener, feiner Stäube erfordert eine hinreichend genaue und empfindliche Multielement-Analysen-methode, die eine schnelle Bestimmung von Serienproben ermöglicht.Es wird über die Untersuchung luftgetragener Staubteilchen und sedimentierter Stadtstäube mittels energiedispersiver Röntgenfluoreszenzspektrometrie mit Sekundärtargetanregung berichtet. Den praktischen Anforderungen einer Spurenbestimmung in umweltrelevanten Staubmatrices wird dabei durch folgende 2 Methoden entsprochen.Feine luftgetragene Staubteilchen unter 3,5m werden auf Nucleopore Membranfilter abgeschieden und direkt mittels EDXRF zerstörungsfrei gemessen. In diesen quasi unendlich dünnen Schichten sind Matrixeffekte und Teilchengrößeneffekte praktisch zu vernachlässigen. Die Eichung erfolgt mittels dünner Schichten, die durch Sputtering von NBS-Gläsern mittels Argon-Ionenstrom hergestellt werden.Werden die Proben mit Li₂B₄O₇ in einem Pt/Au-Tiegel zu homogenen glasartigen Scheibchen geschmolzen, so lassen sich alle Inhomogenitätsund Teilchengrößen-Effekte, die eine Analyse stören, vermeiden. La₂O₃ oder WO₃, den Proben als schwerer Absorber zugesetzt, reduziert die Interelementeffekte der praktisch unendlich dicken Proben. Es wird über ein neu entwickeltes Computerprogramm zur Datenreduktion berichtet, das nach der theoretischen und empirischen Methode für Absorptionsund Interelementeffekte korrigiert. Es wird gezeigt, daß für einige Spurenelemente der Untergrund eine lineare Funktion der incomplete charge collection des Si-(Li-)Detektors ist und auf empirischem Wege einfach berechnet werden kann.Abschließend wird ein Methodenvergleich mit der AAS präsentiert; die Ergebnisse werden mit dem Standardreferenzmaterial NBS Fly Ash verifiziert.

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Presented at the International Symposium on Microchemical Techniques, Davos, May 1977.

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This work was done when K. E. Lorber was at the National Bureau of Standards.     

Conventional and organic potatoes: Assessment of elemental composition using k0-INAA

The elemental composition of potato tubers from four varieties growing in an experimental field under conventional and organic conditions was investigated. Br, Co, K, Na, Rb and Zn, determined by k ₀-instrumental neutron activation analysis, were used to distinguish the tubers according to the cultivation system. The difference between organic and conventional potatoes was evidenced by cluster analysis, specially using Br, Co, K and Rb. This revised version was published online in August 2006 with corrections to the Cover Date.     

Assessment of elemental mobility in soil using a fluidised bed approach with on-line ICP-MS analysis

A new method has been developed to analyse the mobility of elements within soils employing counter-current flow soil contacting in a fluidised bed (FB) column. This method alleviates the problem of irreproducible peaks suffered by state-of-the-art micro-column techniques as a result of particle compaction. Reproducible extraction profiles are produced through the leaching of soil with a linear gradient of 0.05 mol L⁻¹ ammonium sulphate to 0.11 mol L⁻¹ acetic acid using a high pressure liquid chromatography (HPLC) quaternary pump, and the continuous monitoring of the elements in the leachate with inductively coupled plasma mass spectrometry (ICP-MS). Quantification of the procedure is achieved with an external flow injection (FI) calibration method.Flow rate and FB column length were investigated as critical parameters to the efficiency of the extraction methodology. It was found that an increase in the column length from 10 to 20 cm using a flow rate of 0.15 mL min⁻¹ produced the same increase in extracted elemental concentration as an increase in flow rate from 0.15 to 0.30 mL min⁻¹. In both examples, the increase in the concentration of elements leached from the soil may be ascribed to the increase in the concentration gradient between the solid and liquid.The exhaustive nature of the technique defines the maximum leachable concentration within the operationally defined leaching parameters of the exchangeable phase, providing a more accurate assessment of the risk associated with the elements in the soil for the phase providing the greatest risk to the environment.The multi-elemental high sensitivity nature of the on-line detector provides an accurate determination of the associations present between the elements in the soil, and the identification of multiple phases within the exchangeable phase through the presence of multiple peaks in the extraction profiles. It is possible through the deconvolution of these extraction profiles that the concentration corresponding to the peaks identified can be defined.     

Isolation and quantitative analysis of road dust nanoparticles

Nanoparticles are capable of preconcentrating various elements, including toxic ones; they have high mobility in the environment and can easily penetrate into a human body. The study of the chemical composition and properties of road dust nanoparticles is an urgent task of analytical chemistry, which needs to be addressed in the monitoring of the anthropogenic load on the environment and the assessment of the potential danger of pollution to human health. In the present paper, we propose a new approach for the isolation, characterization, and quantitative elemental analysis of road dust nanoparticles. Conditions are selected for the separation of nanoparticles from Moscow dust samples by field-flow fractionation in a rotating coiled column; the resulting fractions are characterized by independent methods (using static light scattering and electron microscopy); the method for calculating the concentration of elements in the nanoparticle fraction according to inductively coupled plasma atomic emission spectrometry and mass spectrometry is improved; elements in a water-soluble form are isolated and determined; and the role of soluble organic matter in the binding of trace elements is discussed. It is shown that the total concentration of most elements in the samples of Moscow dust is comparable to the average values for urban soils. Abnormally high concentrations of several elements (Cu, Zn, Ag, Cd, Sn, Sb, Hg, Pb, Tl, and Bi) are revealed in the fraction of nanoparticles; the enrichment factor with respect to the total concentration ranges from 10 to 450. The source of contamination of road dust nanoparticles with copper, zinc, antimony, and cadmium is highly probable wearing-off of brake pads and car tires. The developed procedure of separation, characterization, and analysis of nanoparticles can be used for other polydisperse environmental samples (for example, volcanic ash).     

Platinum determination by NAA in two road dust matrices

In this work, a method for platinum determination was studied. The method is based on neutron activation analysis coupled with a preirradiation concentration/separation procedure employing a Dowex ion exchange chromatographic column to overcome serious interferences from other elements.Two environmental matrices, Road Dust CW7 and Road Dust CW8, collected and prepared by the Bureau Communautaire de Reference as candidate reference materials, were analysed. Finally, only CW8 was certified as BCR 723. The results were compared with data obtained by other laboratories with various techniques.     

Microwave-assisted digestion procedure for the determination of palladium in road dust

The present publication describes a microwave-assisted digestion procedure for the subsequent trace and ultra-trace analysis of palladium in road dust of varying origin. Digestion reagents are nitric acid, hydrogen peroxide and hydrofluoric acid. Boric acid is used as masking agent for fluoride ions to avoid removal of excess hydrofluoric acid by vaporization. After the three-step digestion procedure, a colorless and residue-free solution is obtained in which the determination of palladium can be directly performed using a recently developed highly selective on-line pre-concentration system, coupled with graphite furnace atomic absorption spectrometry (GF-AAS). Dust samples of varying origin (tunnel dust, road dust, filter dust from Frankfurt, Munich and Japan) and sampling dates (1987-2001) were investigated and characterized in detail with respect to matrix composition and palladium content. Validation of the analytical results was performed by recovery experiments.     

EDXRF imaging of Pb in glazed ceramics using a micropattern gas detector

A new system for energy-resolved X-ray fluorescence imaging using a microhole and strip plate (MHSP), a new type of micropattern gas detector (MPGD), is proposed. It works as a single photon counting detector with position and energy detection capability. The interaction of X-rays with the gas medium produces electrons via the photoelectric effect, and the number of electrons is proportional to the absorbed X-ray energy. These electrons are further multiplied in the MHSP. Position detection is achieved using the charge division method. The detector has an active area of 28?×?28 mm² and shows good position resolution, about σ?=?125 μm, an intrinsic energy resolution of about 14% FWHM for 5.9 keV X-rays, and a counting rate capability of up to 0.5 MHz. The system has shown good properties for energy-dispersive X-ray fluorescence (EDXRF) applications, since it allows efficient energy and position detection of fluorescence X-rays from multielemental samples. In this work, the system was used to study lead depth distributions in eighteenth-century Portuguese faiences from the Santa Clara-a-Velha monastery. The fluorescence images were obtained by irradiating the samples, with a pinhole placed between the sample and the detector to focus the radiation into the detector. The results are presented here, including the elemental map distributions for different samples.     

Assessment of occupational exposure and contamination

In order to assess the elemental concentration level in a galvanizing industry and alert for the need to assess the outcome of a long-term exposure, scalp hair and toenail samples were used as bioindicators and the industry environment was evaluated through airborne particulate matter. The elemental concentration results have pointed out a high exposure to pollutant at workplaces and a high elemental concentration in biomonitors suggesting endogenous contamination. The majority of the elements determined in airborne particulate matter were also determined in hair and toenail samples. The results evidence the efficiency of these matrixes as biomonitors and the importance to carry out the airborne particulate matter sampling in parallel to these biomonitors mainly in occupational epidemiological studies.     

Distribution of major and trace elements concentrations in gold processing using EDXRF

Studies have been carried out on the distribution of major and trace elements concentrations in oxide and sulphide feed ores at various stages of milling and processing of gold in a goldmine at Bogoso in the western region of Ghana. The studies evaluated concentration enhancements at various stages of treatment with emphasis on understanding the typical processes leading to enhancement of concentration at each stage and ultimately the impact from discharges into the surrounding environment. The feed ore samples were analyzed using energy dispersive X-ray fluorescence spectrometry. The results show concentration enhancements of a significant number of elements at some stages of processing in the two processing plants with the highest number of elements with enhanced concentrations coming from chemically treated media of both plants. Though there are relatively high concentrations of V (max.: 284 ppm), Cr (max.: 149 ppm), Co (max.: 84 ppm), and U (max.: 26.8 ppm) at the discharge points, the concentrations of most of the toxic elements in the slurries discharged into the tailings dam are mostly within their respective world averages. The enrichment indices computed for the slurries being discharged into the tailings dam suggests that the dam is not enriched with the toxic elements Cr, Co, Ni, Zn, Cu and Pb. The enrichment index of the slurries discharged into the tailings dam decreases in the order of oxide plant > sulphide plant. Principal component analyses performed suggest that Al₂O₃, K₂O, Co, Zn, Cu, Y and Zr are geochemically associated. Results from the studies also suggest that the discharge of these elements into the tailings dam may contribute insignificant pollution of the surrounding area.     

Effect of change of environmental conditions on the elemental composition of airborne dust

In order to assess the extent of the elimination of humidity and the presence of pine trees on the elemental composition of airborne dust, the concentration of 21 elements were measured in airborne dust collected with a high-volume sampler at JAERI by instrumental neutron activation analysis (INAA). It was found that the concentration of soil-origin elements, such as Al, Sc and Th, decreased as the humidity increased, and the Cl/Na ratio of sea salt constituent in the dust samples increased with the decrease of humidity after the felling of the trees.     

Determination of multi-element profiles of soil at Visakhapatnam using EDXRF technique

In the present study attempt has been made to generate elemental profile database for major sources of soil pollution, specific to Visakhapatnam. Representative road dust and soil samples from major industrial locations were collected and analyzed for various metals distribution using EDXRF. Analysis results indicate that V and Ni were predominant at PR and Zn was found to be dominating in road dust samples. Higher concentration of Arsenic was observed at TPP as compared to all other sites. Cr was found to be dominating at TPP and SP. I _geo calculations suggest that soil is highly contaminated with heavy metal pollutants.     

Studies of kidney stones using INAA,EDXRF and XRD techniques

Four kidney stones collected from patients being treated in the Advance Urology Centre of PGIMR, Chandigarh were characterized using instrumental neutron activation analysis (INAA), energy dispersive X-ray fluorescence (EDXRF) and X-ray diffraction (XRD) techniques. For INAA, samples were irradiated in tray rod facility of Dhruva reactor, Mumbai and pneumatic fast transfer system of KAMINI reactor, IGCAR, Kalpakkam. Radioactive assay was carried out using HPGe detector coupled to 8k channel analyzer. Elements determined in the samples by INAA are Zn, Sr, Co, Fe, Cr, Sc, Se, Na and Mn. EDXRF was used for the quantification of Ca. XRD patterns showed that three of the kidney stones are calcium oxalate stone and the other one is uric acid stone. The concentrations of trace elements in general were found to be higher in calcium oxalate stones and positive correlation was observed in the concentrations of Ca with Sr and Zn.     

Determination of uranium in various matrices using EDXRF and excitation by different radionuclides

The synergistic extractions of uranium(VI) nitrate using HDEHP,^* PMBP^** and TBP^*** have been studied from benzene media. A new method is proposed to calculate the equilibrium constants for such kinds of ternary synergistic extraction systems. The extraction reactions and their equilibrium constants were found. Models for the extraction mechanism are also discussed.     

One-pot efficient synthesis of disulfides from alkyl halides and alkyl tosylates using thiourea and elemental sulfur without contamination by higher polysulfides

An efficient and odorless synthesis of disulfides from alkyl halides using thiourea and elemental sulfur in the presence of sodium carbonate in wet polyethylene glycol (PEG 200) at 40 °C without contamination by higher polysulfides has been developed. This procedure was then extended to preparation of disulfides from alkyl tosylates at 70 °C.