Wavelength Dispersive X-ray Fluorescence Technique Research Articles

Micro PIXE mapping proves a differential distribution and concentration of trace elements in fungal structures of Rhizophagus intraradices

Arbuscular mycorrhizal (AM) fungi can sequester different potentially toxic elements, such as trace elements (TEs), within their structures to alleviate the toxicity for its host plant and themselves. To elucidate the role of AM fungi in TEs immobilization in the rhizosphere of host plants, it is important to know the TEs distribution in AM fungal structures. In the present study, we investigated the distribution and concentration of TEs within extraradical spores and mycelium of the AM fungus Rhizophagus intraradices, collected from the rhizosphere of Senecio bonariensis plants grown in a soil polluted with multiple TEs, by using Particle-Induced X-ray Emission with a micro-focused beam (micro PIXE). This technique enabled the simultaneous micrometric mapping of elements in a sample. The calculated values were compared with those in the polluted substrate, measured by the Wavelength Dispersive X-ray Fluorescence technique. The highest concentrations of Fe, P, Ti, Mn, Cr, Cu and Zn were found in AM fungal spores, where they were accumulated, while extraradical mycelium was enriched in Cu. Finally, we demonstrated that AM fungi can simultaneously accumulate high amounts of different TEs in their structures, thus reducing the toxicity of these elements to its host plant.

Structural characterization of ultrathin diamond-like carbon overcoats for high areal density magnetic recording

This paper reports a comprehensive study on chemical structures of ultrathin diamond-like carbon (DLC) overcoats for high areal density magnetic recording. The DLC overcoats were fabricated in a range of thicknesses between 0.5 and 5.0 nm with Si interlayer on NiFe substrates using a pulsed filtered cathodic vacuum arc (PFCVA) technique. The overcoat thicknesses were accurately determined by high–resolution transmission electron microscopy and wavelength dispersive X-ray fluorescence techniques. The surface morphology, chemical composition, microstructure, and tribological properties were systematically investigated by atomic force microscopy, X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure, Raman spectroscopy techniques, and a reciprocating wear test. The results showed that the surface morphologies of DLC overcoats were atomically smooth with a root mean square surface roughness below 0.23 nm. The DLC overcoats had high sp3 bonds fraction. However, as the overcoat thickness was thinner than 1 nm, the sp2 bonds fraction suddenly increased resulting in a significant increase in the coefficient of friction. The obtained results demonstrated the limitation of the thickness of the DLC overcoat fabricated by the PFCVA technique as a protective coating for high–density magnetic storage devices.

Application and Validation of Analytical Software (SQX) for Semi-Quantitative Determination of the Main Chemical Composition of Solid, Bulk and Powder Fuel Samples by Wavelength Dispersive X-ray Fluorescence Technique

Determination of the content of chemical elements occurring in waste in large, small and trace amounts was performed using two instrumental analysis techniques: ICP-OES—Inductively Coupled Plasma Optical Emission Spectrometry and WDXRF—Wavelength Dispersive X-ray Fluorescence Spectrometry. Since such analyses are expensive and time-consuming, the objective of the work presented in this paper was the development of a quick and inexpensive method for preliminary, scanning-based identification of the chemical composition of tested samples (solid, bulk or powder) using standardless, semi-quantitative analysis. An optimized method of preparing samples for X-ray measurements by pressing into a durable tablet, universal for all materials tested, was developed. Moreover, limits of quantification were determined, and the uncertainty of the results obtained was estimated by comparing them with the results acquired with the use of the accredited calibration method, employing standards and certified reference materials.

Investigation of Soils and Pine Needles Using WDXRF and TXRF Techniques for Assessment of the Environmental Pollution of Shelekhov District, Eastern Siberia, by the Aluminum Industry and Heat Power Engineering

X-ray fluorescence analysis was applied to assess the ecological state of the area potentially polluted by emissions of the aluminum industry and heat power engineering. Soil and pine needle samples were collected in areas with industrial activity and analyzed using wavelength-dispersive X-ray fluorescence (WDXRF) and total-reflection X-ray fluorescence (TXRF) techniques. Both techniques were validated using the matrix-matched certified reference materials. Different sample preparation procedures, such as fusion and pressing for WDXRF and acid digestion and suspensions for TXRF as well as quantification approaches (the external calibration for WDXRF and the internal standard for TXRF) were applied according to the features of the analyzed samples. The rock-forming oxides (Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, MnO, and Fe2O3) and trace elements (V, Cr, Ni, Cu, Zn, Rb, Sr, Y, Ba, and Pb) were quantified in soils, as well as several elements (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Pb, and Ba) were quantified in pine needles. Comparing the results of soils and pine needles analysis with the regional background values indicated a significant contamination pollution level of the studied area.

Rapid elemental composition analysis of spinach samples employing wavelength dispersive X-ray fluorescence spectroscopy

The increasing demand to carry out nondestructive analysis with minimal sample preparation for the detection of chlorine element in the spinach samples requires advanced analytical techniques with better energy resolution. The emergence of wavelength dispersive X-ray fluorescence instruments offers new chances for fast and inexpensive plant leaf analysis, both as laboratory and in-situ-based systems. Earlier efforts to use X-ray fluorescence analyses for various plant samples, especially spinach leaves, were limited by the large background caused by scattering of the primary X-ray source which has been overcome by using the commercial wavelength dispersive technique. It is a potential influential research tool for the study of trace elemental composition analysis under different analytical parameters and simple sample preparation protocols. In the present work, the chlorine content ∼0.8% has been measured in the spinach leaf standard reference material (SRM 1570a) from the National Institute of Standards and Technology, USA by using the wavelength dispersive X-ray fluorescence technique employing a fundamental parameter approach. Keeping in view the importance of the knowledge about the chlorine content in plant leaf samples and the reliability of the methodology used in the present work to determine chlorine content, it is recommended that the present measured chlorin.e concentration be included in the datasheet of certified values by the National Institute of Standards and Technology, the USA for effective use of this standard reference material.

Determination of La, Ce, Nd, Sm, and Gd in mineral waste from cassiterite beneficiation by wavelength-dispersive X-ray fluorescence spectrometry

The objective of this study was to establish the best parameters to correct for matrix effects in the chemical analysis of a siliceous geologic material rich in metallic elements of high economic value, such as La, Ce, Nd, Sm, and Gd (rare earth elements), using empirical influence coefficients applied to wavelength dispersive X-ray fluorescence (WDXRF). At present, this material is considered waste derived from the extraction of tin from cassiterite, a special ore from which niobium and tantalum are also processed. In this study, a reliable methodology for the analysis of rare earth elements in a siliceous matrix using the WDXRF technique was developed. This procedure may be useful in promoting industrial processes for chemical control in solid matrices, as the usual techniques are only possible in liquid media and require acid dissolution.

Assessment of Vegetables and Soils from Minjingu Village-Tanzania using WDXRF Technique

Wavelength dispersive x-ray fluorescence (WDXRF) spectrometer was used to analyze heavy metal concentration in soils and vegetables. The soil and vegetable samples were randomly collected from Minjingu village of Manyara region in Tanzania. The results indicate the soils to be contaminated with heavy metals with mean concentrations of 53±0.4 For Mn, 40±0.2 for Sr, 2059±4.2 for Fe, 760±2.7 for Al, 12±0.3 for Cs and 4±0.04 for Ni in mg/kg which was above the Maximum Tolerable Limits (MTLs). Except Cl was below MDL. While vegetables recorded the mean concentrations of 60±1.2 for Mn, 68±0.1 for Sr, 620±2.36 for Fe, 284±1,13 for Al, 56±0.5 for Cs, 13±0.1 for Ni and 714±0.7 for Cl in mg/kg. The reference and experimental results of soil and vegetables revealed that the optimized machine has given the best results, where the experimental data was very close to the reference values The reference material of soil 7 and International Atomic Energy Agency (IAEA) 395 for vegetables shows the deviation of less than 2%.The Minimum Detection Limit (MDL) for vegetables and soil of the WDXRF spectrometer was obtained under low back ground for different matrix effects. There were high correlation coefficient of heavy metals in soils and vegetables at 99% level. The findings indicate that Minjingu soils and grown vegetables were highly contaminated with heavy metals mainly from soils and polluted air, at levels able to pose detrimental health effects to the consumers. Thus need of regular monitoring of the grown vegetables around phosphate mines is recommended.

Quantitative estimation of total potassium and 40K in surface soil samples of Indian Sundarbans

The present study attempts to quantitatively estimate total potassium content in soil samples collected from different areas of Indian Sundarbans by gamma-spectrometry, exploiting the radiogenic properties of potassium and by wavelength dispersive X-ray fluorescence technique. The elemental K concentration varied in between 2.08 ± 0.05 and 3.46 ± 0.06% in the soil samples. Besides estimation of total potassium, the activity of 40K was also estimated in the same soil samples and found to be in the range of 532 ± 8.9 to 1043 ± 13.2 Bq kg−1.

Health-Related Analysis of Uranium in Fazilka District, Punjab, India

Laser fluorimetry technique has been used to estimate uranium concentration in groundwater samples collected from 20 villages of Fazilka district, Punjab, India. The uranium concentration was found to vary from 4.32 to 83.99 μg l –1 at different locations with mean concentration of 26.51 μg l –1 . Also, 24% of the drinking water samples exceeded the safe limits set by WHO, while 9% was above the limit set by AERB. Certain health risk factors like annual effective dose, excess cancer risk and lifetime average daily dose were also evaluated. The study also included uranium estimation in soil samples collected from the same villages using wavelength dispersive X-ray fluorescence technique. All the values were found to be well within the safe limits. Topography of the region seems to be the most likely reason for higher uranium concentration at some locations.

Quantitative X-ray analysis for Cr–Fe binary ferroalloys by using EDXRF−WDXRF techniques

Quantitative analysis of materials is significant for its potential usage in different areas. In the present study, quantitative analysis for Fe–Cr binary ferroalloys was evaluated by using Energy Dispersive X-Ray Fluorescence (EDXRF) system and the classical α-coefficient equation. The ferroalloys were prepared from powder form of Fe and Cr elements. The ferroalloys were excited by 59.54 keV γ-rays from 241Am annular radioactive source in EDXRF and K α X-ray fluorescence spectra of Fe were analyzed in the binary matrices for determining analyte element Fe. Also, Wavelength Dispersive X-Ray Fluorescence (WDXRF) system was used to compare the concentrations of the analyte. The agreement was found to be quite satisfactory between the EDXRF and WDXRF (≤1.76 relative difference (%) between concentrations), and it should be noted that the classical α-coefficient equation is highly reliable approach for quantitative analysis of ferroalloys. In addition, effective atomic numbers (Z eff ) of alloys were calculated using scattering ratio (R/C) method and fitted to concentrations obtained of alloys for fit equation.

Classification of Chemical Elements Present in Daily Materials in Orthotics and Prosthetics

In this paper we analyze the chemical composition of materials used daily in the field of Orthotics, Prosthetics and Assistive Technology, which act as the interface of contact between the prosthetic/orthotic element and the patient's skin. The methodology is experimental, using the wavelength dispersive X-ray fluorescence technique, applied to samples of wool and synthetic cloth. To perform these studies, we used special equipment belonging to the Management of Chemistry, National Atomic Energy Commission, and the measurements were made in collaboration with personnel of this institution.

Analytical approaches for determination of bromine in sediment core samples by X-ray fluorescence spectrometry

Bromine has been recognized as a valuable indicator for paleoclimatic studies. Wavelength dispersive X-ray fluorescence (WDXRF) and total reflection X-ray fluorescence (TXRF) methods were applied to study the bromine distributions in lake sediment cores. Conventional WDXRF technique usually requires relatively large mass of a sediment sample and a set of calibration samples. Some analytical approaches were developed to apply WDXRF to small sediment core samples in the absence of adequate calibration samples with a known Br content. The mass of a sample to be analyzed was reduced up to 200–300mg and the internal standard method with correction using fundamental parameters was developed for Br quantification. TXRF technique based on the direct analysis of a solid suspension using 20mg of sediment sample by internal standard method was additionally tested. The accuracy of the WDXRF and TXRF techniques was assessed by the comparative analysis of reference materials of sediments, soil and biological samples. In general, good agreement was achieved between the reference values and the measured values. The detection limits of Br were 1mg/kg and 0.4mg/kg for WDXRF and TXRF respectively. The results of the Br determination obtained with different XRF techniques were comparable to each other and used for paleoclimatic reconstructions.

Strategies for overcoming limitations associated with fluorine determination in solid materials by conventional wavelength dispersive X-ray fluorescence spectrometry

Potential ways to avoid limitations and improve analytical sensitivity in the determination of fluorine (F) in solid materials using wavelength dispersive X-ray fluorescence (WDXRF) spectrometry were investigated. Chemical shift was not significant in the F determination using WDXRF spectrometry, potentially because of high electronegativity of F. In a variety of matrices containing F, an absorption/enhancement effect noticeably altered the F intensity. A sample containing high-molecular-weight constituents seemed to absorb the emitted F-Kα line more than its counterparts. An additional calibration curve established using standards with similar matrices to samples is recommended. In addition, the intensity induced from the F-Kα increased by more than 9-fold by making a pressed pellet with a low dilution (9:1) method using polyvinyl alcohol and liquid binder. Peak overlap caused by the proximity between F-Kα and Fe-Lα or Mn-Lα is likely to disturb the quantitative F determination. It can be properly overcome by employing a correction factor derived from the slope of the measured X-ray intensity at the Bragg angle of 43.174° to Fe or Mn content in the sample. Consequently, WDXRF technique can be successfully used to assess the F content in solid materials by following the strategies proposed in this study.

The effect of chemical modification on the physico-chemical characteristics of halloysite: FTIR, XRF, and XRD studies

The effect of chemical modification of halloysite from a Polish strip mine “Dunino” on the chemical composition and structure of this clay mineral was studied using infrared spectroscopy (ATR FT-IR), wavelength dispersive X-ray fluorescence (WDXRF), and X-ray powder diffraction (XRPD) methods. The results obtained by the WDXRF technique confirm that the content of silica and alumina was the highest for bleached halloysite samples and the lowest for acid-treated halloysite. A higher content of Fe2O3 in comparison to halloysite samples coming from other countries was observed for raw halloysite samples. XRPD diffraction pattern obtained for raw halloysite confirmed the presence of halloysite, kaolinite, hematite, and calcite minerals in the sample. Bleaching the halloysite removes (or significantly reduces) the content of other minerals present in the raw halloysite. The FT-IR spectra of the studied halloysite samples show in the 3700–3600cm−1 region well-defined hydroxyl stretching bands characteristic for the kaolin-group minerals and bands associated with the vibrations of the aluminium–silicon skeleton in the 1400–1000cm−1 region. Modifying halloysite with 4-chloro-aniline causes successive incorporation of amine into the BH sample.

Elucidation of fluorine in SnO2:F sprayed films by different spectroscopic techniques

The aim of the present work is to explore a suitable spectroscopic technique for accurate determination of fluorine in the fluorine doped tin oxide (SnO2:F) thin films whereas accurate determination of fluorine in SnO2:F thin films was not clarified in the literature. For this purpose, fluorine doped tin oxide (SnO2:F) thin films were prepared on cleaned glass substrates by spray pyrolysis technique using SnCl4 and NH4F as precursor for SnO2 and fluorine dopants respectively. Five different spectroscopic techniques which are mostly used for characterization of the different thin films were used in order to understand the actual behavior of fluorine inside SnO2:F thin films. These techniques are electron probe microanalysis (EPMA), scanning electron microscope (SEM), wavelength dispersive X-ray fluorescence (WDXRF), X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering (RBS). Acceptable agreements of quantitative analysis of fluorine in SnO2:F thin films was obtained by using WDXRF and RBS techniques. It was found that, the real fluorine content in SnO2:F thin films is not representing the content of the prepared solutions for spray pyrolysis. The real content of fluorine represents only ∼10% from the imbedded concentration of fluorine whereas ∼90% was lost during the deposition process of the thin films using spray pyrolysis technique.

Application of the wavelength dispersive X-ray fluorescence technique to determine soil fluorine with consideration of iron content in the matrix

The suitability of the wavelength dispersive X-ray fluorescence (WD-XRF) technique for the quantitative analysis of fluorine in soil was assessed in this study. Fluorine standards for WD-XRF calibration with soil matrices consisting of SiO2, Al2O3, Fe2O3, and CaO were prepared by varying the concentrations of CaF2 as a source of fluorine. Based on the standard calibration, the limits of detection and quantification were calculated as 812 and 2690mg-F/kg-solid (or 1.62 and 5.39mg-F in absolute mass term), respectively. In addition, the fluorine intensities of the standard samples with high iron content increased significantly compared to those with low iron content. Because of proximity between F-Kα and Fe-Lα line, the higher iron content preferably helped increase background fluorine intensities. As a means to compensate for the iron interference effect in fluorine analysis, the correction factor (CF) (0.0045) was derived based on the slope ratios between the measured X-ray intensity at the Bragg angle of 43.174° and iron content in the standard sample. The soil fluorine concentration determined by WD-XRF after the CF adjustment exhibited a significantly high correlation with that of the classical alkali fusion-ISE analysis. These findings clearly demonstrated that the WD-XRF technique is reliable enough to allow an easy, precise, and rapid quantitative determination of fluorine in a solid sample (such as iron-bound soil) compared to conventional methods.

Determination of chilling temperature effects on nutrient elements composition and distribution in cole (Brassica oleracea L. Cv. Acephala) using the WDXRF spectroscopic technique

Cole (Brassica oleracea L. cv. Acephala) is a naturally very hardy species to (at) chilling temperatures. It has been observed that the plant species can be viable even under snow during a cold winter. The cole seedlings were grown in soil for one month. Chilling temperatures were then applied to these seedlings under controlled conditions. These seedlings were subsequently, cut into root tip, root middle part, root upper part, hypocotyl, epicotyl, petiole and leaf and sampled randomly. Concentrations of inorganic elements (Al, Si, P, S, Cl, K, Ca, Fe, and Mg) in the parts were measured by wavelength-dispersive X-ray fluorescence (WDXRF) spectrometry to test chilling temperature effects on nutrient accumulation and distribution within these seedlings. Results indicated that the distribution of some inorganic elements among organs (roots, stem and leaves) of cole plants is significantly altered by chilling stress. There was an association between chilling temperatures and distributions, and accumulations of Ca, Fe, P, Cl, S especially Si and Al in cole seedlings. In addition, the WDXRF technique is a simple, fast, economic and accurate tool for biological studies related to the determining of the amount of plant nutritions in ppm level.

Petrographic and geochemical analysis on the provenance of the Middle Bronze and Late Bronze/Early Iron Age ceramics from Didi Gora and Udabno I, Eastern Georgia

We report thin section petrographic and geochemical analysis of a total of 20 Middle Bronze, Late Bronze/Early Iron Age ceramics excavated from Didi Gora and Udabno I located in the Eastern part of the Republic of Georgia and 31 clay samples from eight different regions in the surrounding areas of the sites. The major and trace element compositions of the ceramics and clays were determined using a wavelength dispersive X-ray fluorescence technique. The results indicate that the ceramics were manufactured from local clays in Eastern Georgia, mainly from two local clays without any preference of one of the sources during the Middle Bronze, Late Bronze/Early Iron Age.

Multielemental analysis of dried residue from metal-bearing waters by wavelength dispersive X-ray fluorescence spectrometry

The purpose of this work was evaluation of instrumental sensitivity and detection limits for determination of elemental composition (20 different elements ranging from Na to Pb) of liquid mining samples by using conventional Wavelength Dispersive X-Ray Fluorescence (WDXRF) instrumentation. Preconcentration of elements from liquid samples was performed by means of a simple dried residue process, and spectral evaluation was carried out by integration of the peak area (using WinQXAS/AXIL package software, International Atomic Energy Agency (IAEA)) instead of the common net peak line intensity traditionally used in conventional WDXRF systems. With the proposed methodology, the calculated detection limits were in the µg L − 1 range (from 0.005 to 0.1 mg L − 1 level depending on the element) in all cases, which is suitable for element determination in most liquid samples involved in environmental studies such as metal mining liquid effluents. The detection limits are also below the established limits of the TCLP 1311 (United States Environmental Protection Agency (US-EPA)) and DIN 38414-S4 (German Standard legislation) procedures, which are commonly used to evaluate the leaching of metals from landfill disposal. Accuracy of the procedure was confirmed by analysis, based on the German Standard Method DIN 3814-S4, of water lixiviates from three overbank sediment samples collected in two abandoned mining areas. The attained results were compared with those obtained by inductively coupled plasma (ICP) techniques, and acceptable agreement for elements with Z > 20 was found. This study highlights the possibility of using a simple methodology for analysis of liquid mining samples using the WDXRF technique, commonly employed for geochemical exploration of solid samples in environmental studies.

Validation of a method for the determination of boron in ceramic materials by X-ray fluorescence spectrometry

A method is proposed for boron determination in ceramic materials, boracic raw materials and ceramics frits of different compositions by wavelength dispersive X-ray fluorescence technique. The instrumental conditions were studied and the sample preparation procedures were optimized. The reference method used was the potentiometric titration of mannitol–boric complex acid and the technique was optimized for the determination of B 2O 3 in each of the materials used. The samples for XRF determination were obtained as pellets and as glass discs. For the pellets different binders were studied, such as mannitol and cellullose for the samples of raw materials, and polyvinylpirrolidone and methyl cellullose (PVP+MC) for the ceramic frits. Samples were obtained in the form of glass discs using lithium tetraborate and a barium-lead glass (BaPbG) as materials to melt, dilute and homogenize the samples, and increase the analytical signal. A series of calibration curves were obtained and the instrumental variables were optimized. The results obtained with the XRF method were compared with the reference method for several unknown samples. The results obtained with both techniques showed relative errors from 0.7 to 3.2% for B 2O 3 content ranging between 40.8 and 6.3%, respectively.