Total Reflection X-ray Fluorescence Analysis Research Articles

Consideration of spectral interference in total reflection X-ray fluorescence analysis using a limited number of calibration samples: Case study of ocean polymetallic nodules

Consideration of spectral interference in total reflection X-ray fluorescence analysis using a limited number of calibration samples: Case study of ocean polymetallic nodules

Exploring the analytical potential of total reflection X-ray fluorescence (TXRF) combined with partial least square (PLS) for simple determination of ash content in various coal types

Ash content, as a crucial indicator of coal quality, its rapid and accurate determination is pivotal to improve the energy utilization of coal and reduce environmental pollution. Traditional spectroscopic methods face significant challenges in acquiring accurate information from coal samples due to the notorious matrix effects arising from their complex composition, vast molecular structure, and diverse coal types. In this study, the feasibility of total reflection X-ray fluorescence (TXRF) combined with partial least squares (PLS) for the determination of coal ash was firstly investigated based on the TXRF being unaffected by matrix effects. Firstly, coal samples were prepared as suspensions, and the effects of sample particle size and different dispersants on the results of TXRF analyses were evaluated. The accuracy and applicability of the chosen sample preparation strategies were further validated using inductively coupled plasma mass spectrometry (ICP-MS) and two certified reference materials (CRMs). Subsequently, based on the analysis of 19 coal samples, the impact of three different predictive variables on the performance of the PLS model was investigated: (a) TXRF full spectrum normalized by the net intensity of the internal standard; (b) net intensity of characteristic peaks for 12 elements (Al, Si, K, Ca, Ti, Fe, Cr, Mn, Cu, Ni, and Sr) normalized by the net intensity of the internal standard; (c) concentrations of the aforementioned 12 elements. The results demonstrate that the PLS model constructed usingthe TXRF full spectrum normalized by the net intensity of the internal standard exhibits the best predictive capabilities, with the determination coefficient of calibration set (R2) and mean square error (MSE) of the prediction set reaching 0.9736 and 0.99 %, respectively. Moreover, the measurement accuracy of this model was six times greater than that obtained with traditional X-ray fluorescence (XRF). Presented analytical results display the possibilities of combining TXRF with PLS for coal quality evaluation.

Determination of S, Ni, Cu in copper-nickel sulfide ores by total reflection X-ray fluorescence analysis: experience of participation in the interlaboratory comparisons

The quality of the determination of S, Ni, Cu in copper-nickel sulfide ores was assessed in the framework of the program for interlaboratory comparative tests (ICT) using total reflection X-ray fluorescence analysis (TXRF) taking into account the criteria for methods for determining the chemical composition of mineral raw materials. Certified TXRF techniques for the analysis of mineral materials are absent, so the interlaboratory comparison test was used to control and improve the accuracy of measurements by TXRF. Powdered ore samples were prepared as suspensions by wet grinding: 100 mg of the powder, 4 ml of ultra-pure water and 250 μl of the Ga standard solution were milled using 20 g of ZrO2 balls 1 mm in diameter in the mixing mill for 10 minutes at a frequency of 20 Hz. The ratio of the intensities of the characteristic lines of the analyzed elements and the Ga internal standard was chosen as an analytical signal. To plot calibration curves, a set of ore reference samples was analyzed using certified procedures (atomic absorption spectrometry for Cu, Ni, gravimetry for S). The quality of the TXRF analysis was assessed by the value of Z-criterion. The measurement error did not exceed 5 rel. %. The relative percentage differences between the TXRF results and the results obtained in the interlaboratory study was less than 10%. The described method can be used for rapid analysis of copper-nickel sulfide ores.

Radiation Techniques for Tracking the Progress of the Hydrometallurgical Leaching Process: A Case Study of Mn and Zn

With advancements in hardware and software, non-destructive radiometric analytical methods have become popular in a wide range of applications. A typical case is the study of the leaching process of metals from mineral ores and mine tailings. The objective of the current study was to develop a radiometric method based on neutron activation analysis (NAA), in particular, delayed gamma neutron activation analysis (DGNAA), to monitor the process of Mn and Zn leaching from Ti ore, Cu mine tailings, and Zn-Pb mine tailings. The DGNAA method was performed using a neutron source: a deuterium-tritium (D-T) neutron generator for Mn and a MARIA research nuclear reactor for Zn. Laboratory-scale Mn leaching from Ti ores, Cu tailings, and Zn-Pb tailings was investigated using delayed gamma-rays of 56Mn (half-life of 2.6 h). The dissolution efficiencies of Mn were found to increase with interaction time and HCl concentration (1 to 5 M) and to vary with the leaching temperature (22.5 to 110 °C). Such results were found to agree with those obtained by total reflection X-ray fluorescence (TXRF) spectrometry for the same samples. 65Zn (half-life of 244 days) was chosen to investigate real-time/online leaching of Zn in Ti ore, Cu tailings, and Zn-Pb tailings. During online monitoring, Zn recovery was also reported to increase with increased leaching time. After approximately 300 min of leaching, 80%, 79%, and 53% recovery of Zn in Zn-Pb tailings, Ti ore, and Cu tailings, respectively, were reported. Theoretically, developed mathematical prediction models for 65Zn radiotracer analysis showed that the spherical diffusion model requires much less time to attain saturation compared to the linear diffusion model. The results of NAA for Zn were compared with those obtained by handheld X-ray fluorescence (handheld-XRF) and TXRF analysis. The analyzed samples encompassed leached Ti ore, Cu tailings, and Zn-Pb tailings which were subjected to different conditions of leaching time, temperature, and HCl concentrations. The XRF analysis confirmed that the leaching efficiencies of Zn rise with the increase in leaching time and HCl concentration and fluctuate with leaching temperature. The developed approach is important and can be applied in laboratories and industrial setups for online monitoring of the recovery of any element whose isotopes can be activated using neutrons. The efficiency of the metal-recovery process has a direct impact on the normal operation and economic advantages of hydrometallurgy.

Sample preparation using plasma jet treatment for total reflection X-ray fluorescence analysis

Total reflection X-ray fluorescence (TXRF) is widely used for trace element analysis. This method is advantageous because of its simple sample preparation. However, the sample must be placed within the analytical volume (region and height). In this study, the analytical volume was experimentally evaluated and visualized using thin, localized Au layers. The intensity distributions of the Au Lβ lines and background Au Lβ peaks were visualized. Images of the intensity ratio of the Au Lβ line and the background peak were drawn and analyzed to determine the analysis region on the glass substrate depending on the glancing angle. A glancing angle of 0.025° was optimal for TXRF analysis, resulting in a large signal-to-background (SB) ratio. Glancing angles of 0.05° and 0.075° were also effective for obtaining large SB ratios for a relatively large area (>4 mm2). To reduce the thickness of the dried residue and the self-absorption of the XRF emitted from the residue, a glass substrate was subjected to He plasma jet treatment. X-ray photoelectron spectroscopy confirmed that the carbon contamination was reduced from the surface of the glass by the plasma jet treatment, thereby modifying the chemical properties to confer hydrophilicity to the glass surface. The time variation of the C1 s peak intensity suggests that the hydrophilic property was maintained for several hours. The plasma-treated glass was effective in obtaining a thin layer-like residue from a white wine sample. The TXRF results indicated improved recovery and RSD, particularly for low-Z elements, because the absorption effect was reduced in the thin layer-like residue.

Quantification of [99Tc]TcO4- in urine by means of anion-exchange chromatography–aerosol desolvation nebulization–inductively coupled plasma–mass spectrometry

To sensitively determine 99Tc, a new method for internal quantification of its most common and stable species, [99Tc]TcO4-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{O}}_{4}^{-}$$\\end{document}, was developed. Anion-exchange chromatography (IC) was coupled to inductively coupled plasma–mass spectrometry (ICP-MS) and equipped with an aerosol desolvation system to provide enhanced detection power. Due to a lack of commercial Tc standards, an isotope dilution-like approach using a Ru spike and called isobaric dilution analysis (IBDA) was used for internal quantification of 99Tc. This approach required knowledge of the sensitivities of 99Ru and 99Tc in ICP-MS. The latter was determined using an in-house prepared standard manufactured from decayed medical 99mTc-generator eluates. This standard was cleaned and preconcentrated using extraction chromatography with TEVA resin and quantified via total reflection X-ray fluorescence (TXRF) analysis. IC coupled to ICP-MS enabled to separate, detect and quantify [99Tc]TcO4-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{O}}_{4}^{-}$$\\end{document} as most stable Tc species in complex environments, which was demonstrated in a proof of concept. We quantified this species in untreated and undiluted raw urine collected from a patient, who previously underwent scintigraphy with a 99mTc-tracer, and determined a concentration of 19.6 ± 0.5 ng L−1. The developed method has a high utility to characterize a range of Tc-based radiopharmaceuticals, to determine concentrations, purity, and degradation products in complex samples without the need to assess activity parameters of 99(m)Tc.Graphical

Evaluations of the optimal plasma treated area in total reflection X-ray fluorescence analysis and the retention period of superhydrophilic ability of the substrate

An atmospheric pressure plasma jet was applied to control the form of a dried residue for total reflection X-ray fluorescence analysis.

Titanium dioxide release behavior during wash of UV-protective garments by total reflection X-ray fluorescence

The increasing worldwide use of different kinds of clothes with ultraviolet protection in recent years, in particular employing titanium dioxide nanoparticles, is driving the researchers’ attention to the possible environmental problems due to titanium release. This study aims at determining the amount of titanium released from seven ultraviolet-protective garments into the wash water employing total reflection X-ray fluorescence spectrometry. For this, a wash protocol was designed based on the international standard ISO 105-C06:2010 and the literature. Pieces (4 cm × 10 cm) of textile were sampled from the garments and submitted 30 times to the wash protocol. The wash water produced in each wash was then prepared for total reflection X-ray fluorescence analysis. Results showed that the titanium released in 30 washes was between 8.6 ± 1.3 µg/L and 168 ± 3 µg/L. Every sample released titanium in the first to third wash, except sample 1, which first released titanium in the 18th wash. The greatest titanium release in one single wash was also the 18th wash of sample 1, which released 77 ± 2 µg/L. These results showed the good performance of total reflection X-ray fluorescence spectrometry in quantifying low titanium amounts in wash water, which is a hard task even for well-established analytical methods.

Are Twin Pregnancies at Higher Risk for Iron and Calcium Deficiency than Singleton Pregnancies?

The aim of this study was to compare the iron and calcium status in singleton and twin pregnancies and to assess whether there is an increased risk for iron and calcium deficiency in twin gestation. The study included 105 singleton and 9 twin pregnancies at or above 35 weeks of gestation. Information on prenatal supplementation with iron or calcium was acquired, and adverse perinatal outcomes were recorded. Biosamples from all 114 mothers and 73 newborns (61 singleton and 12 twin newborns) were finally analyzed. Total iron and calcium concentrations in serum were measured through total reflection X-ray fluorescence analysis. The results indicated no significant differences in maternal serum iron and calcium concentrations between singleton and twin pregnancies. Similarly, iron and calcium concentrations in newborn umbilical cord serum samples were not different between singleton and twin pregnancies. The comparison of total iron and calcium between mothers and umbilical cord serum indicated significantly lower concentrations in the mothers, with the differences being not homogenous but rather pair-specific. A significant positive correlation between maternal serum and umbilical cord serum calcium concentration was noticed. Prenatal iron supplementation was associated with higher iron concentrations in both mothers and newborns, supporting the efficiency of supplementation and the quality of the study methods. Collectively, the data indicate no significant differences in serum iron and calcium concentrations with regard to singleton or twin pregnancies and the efficiency of iron supplementation during pregnancy for increasing iron status.

New quantification approaches for total-reflection X-ray fluorescence analysis of micro-sized samples: Apatite case study

Sensitive methods for quantitative elemental analysis of micro-sized samples are limited. In this study, total-reflection X-ray fluorescence (TXRF) method was applied as fast and cost-efficient method to apatite microcrystals. In situ acid digestion based on direct treatment of single crystal onto the carrier was used as sample preparation strategy. Since the internal standard addition is complicated in the case of micro-sized samples, new quantification approaches based on external calibration for TXRF analysis of apatite were offered. An experimental design was created for apatite samples with a differentiation of specimen masses from 1.0 to 100 μg to find patterns in the spectral information. A workflow has been proposed for analyzing apatite crystals of various sizes (100, 500, 1000 µm) with TXRF based on an external calibration using an apatite powder sample as a standard and normalizing the spectra to the P-Kα and Mo-Kα peaks. The conditions of the workflow should be the following: Ca/P ratio is in a range between 19 and 23, and a dead time value does not exceed 4.0 %. The dead time value was used as a main factor of quantification, when calibration sample should match the unknown sample. Limit of detection values of the proposed method are from 1.0 to 100 μg/g depending on the crystal size and element of interest. Validation of the TXRF method was performed by analysis of Durango and McClure apatite samples. Comparison of TXRF results with laser ablation inductively coupled plasma mass spectrometry data showed the good agreement between two methods.

High-accuracy total reflection X-ray fluorescence analysis for determining trace elements using substrate cleaned by ammonia-hydrogen peroxide mixture

Total reflection X-ray fluorescence (TXRF) analysis is one of the useful techniques for determining trace elements. Owing to the high detection sensitivity of X-ray fluorescence in small residues, the hydrophobic substrates are generally used to form dot-type residue. However, when measuring low-Z elements in sample solutions with high concentrations of matrix elements, obtaining sufficient measurement sensitivity can be difficult. X-ray fluorescence is absorbed by the matrix elements, which means that the absorption effect increases in the thicker dried residue compared to the thinner dried residue. To avoid this absorption effect, we have proposed a thin film-type residue. In this study, the glass substrate was treated with an ammonia-hydrogen peroxide mixture (APM). The hydrogen peroxide decomposes organic components, and ammonia slightly etches glass materials. The APM-treated region was limited to a diameter of 6 mm by using a polytetrafluoroethylene mask placed on the glass substrate. As a result, the surface is refreshed to expose the hydroxyl group to make it superhydrophilic. The measured contact angle was 5°. By using the APM-treated superhydrophilic substrate to prepare dried residue, the net intensities in low Z elements were improved. The ratio of Al Kα intensity, calculated as net intensity in the APM-treated substrate divided by it in the hydrophobic substrate, was 2.29. The recovery of each element in the APM-treated substrate was almost 100%; however, recoveries of elements (Al, P, K, and Ca) in the hydrophobic substrate showed significant deviations from 100% (the recovery of Al was approximately 32%). In summary, we successfully improved both analytical sensitivity and accuracy in TXRF analysis by using the APM treated substrate.

Chelate complexed multi-elemental printing performance of a small and cost efficient picoliter droplet printing device for micro preparation

We introduce an inexpensive modular picoliter pipetting device using modified commercially available thermal inkjet cartridges. The system is capable of reliable deposition of 65 elements. The printing solutions were modified to prevent the dissolution of Ni from the nozzle head, keeping those at a pH of >9. Loss of cations to the glass surfaces inside the nozzle head is prevented by forming anionic complexes with ethylenediaminetetraacetic acid in basic conditions. For some elements, e.g., Si, additives like tetramethylammonium hydroxide are necessary.The volumes of the droplets were obtained, weighing 30,000–360,000 droplets ejected by the printer using a laboratory scale. The droplet volume was within a range of 142–184 pL, depending on the formulation. The delivered elemental masses and the reproducibility were determined using total reflection X-ray fluorescence analysis and inductively coupled plasma optical emission spectrometry. Delivered masses were in the range of 0.98 pg – 11.9 pg per element and droplet.The shape of deposits of about 31 pg per element was studied using atomic force microscopy, optical microscopy, and confocal laser scanning microscopy. They were mostly spherical and ca. 14 μm in diameter and ca. 2 μm in height. The broad range of printable elements allows for the micro preparation of solid compounds for establishing a grazing incidence X-ray diffraction analysis library. As an example, the MgAl2O4 spinel was synthesized by printing of the formulation and subsequent calcination. Here we show its performance for the preparation of minerals in the context of recycling of critical elements from pyrometallurgical slags.

Development of Sample Preparation Methods for Vitamin-Mineral Complexes and Determination of their Elemental Composition Using Total Reflection X-Ray Fluorescence Analysis

Development of Sample Preparation Methods for Vitamin-Mineral Complexes and Determination of their Elemental Composition Using Total Reflection X-Ray Fluorescence Analysis

Rapid Water Quality Analysis by Total Reflection X-ray Fluorescence Analysis

Rapid Water Quality Analysis by Total Reflection X-ray Fluorescence Analysis

Improvement of suspension-assisted total reflection X-ray fluorescence analysis of ores using wet grinding and empirical calibrations

In this study, the suspension-assisted total-reflection X-ray fluorescence analysis of ores was improved using the wet grinding procedure to produce ultra-fine suspended powder mixed with internal standard solution in aqueous media. The advantages of the proposed technique were demonstrated by the example of the determination of S, Fe, Ni, and Cu in sulfide copper‑nickel ores containing various ratios of sulfide and silicate minerals. We showed that the powerful mixing of 100 mg of ore powder and 4 mL of ultra-pure water as a dispersing medium with 20 g of grinding balls of 1 mm in diameter leads to the preparation of homogeneous suspension with monomodal particle size distribution having 90% of the particle size <6 μm. The suspension after wet grinding was diluted up to 50 mL with ultra-pure water to obtain a final concentration of the suspended powder of 2 mg/mL. Relative precision of the described sample preparation technique calculated from duplicate pairs of suspensions was 16% for S, 9% for Fe, 15% for Ni and 10% for Cu. Three spectral data processing techniques were further compared with respect to the quantification accuracy of target elements: internal standard, univariate and multivariate regressions. It was shown that the two latter methods can be used to improve the trueness of the internal standard method, especially for Cu and Fe.

Synthesis of Trimetallic (Ni-Cu)@Ag Core@Shell Nanoparticles without Stabilizing Materials for Antibacterial Applications.

We report a simple method to prepare colloidal trimetallic (Ni-Cu)@Ag core@shell nanoparticles (NPs) without stabilizing materials. Experimental evidence was found for the successful synthesis of these NPs using X-ray diffraction (XRD), optical spectroscopy, and high-resolution transmission electron microscopy (HRTEM). The presence of core metals (Ni and Cu) was confirmed by elemental analysis using a total reflection X-ray fluorescence (TXRF) analysis. In addition, the absorption spectra of the prepared samples exhibited broad bands compared to the bands of the monometallic NPs, indicating the formation of a core–shell nanostructure. The antibacterial activity of the trimetallic NPs was evaluated against three Gram-negative (Pseudomonas aeruginosa, Escherichia coli, and Salmonella) and two Gram-positive (Streptococcus and Staphylococcus aureus) bacteria on Mueller–Hinton agar. These NPs showed high inhibition of bacterial growth at the low sample concentrations used in this study compared to other nanomaterials. One of the interesting results of the current study is that the inhibition zone of Pseudomonas aeruginosa as a resistant bacterium was high for most NPs. These results make the prepared samples promising candidates for antibiotic material applications.

Determination of Impurities in Graphite Using Proton Induced Gamma Ray Emission, Total Reflection X-ray Fluorescence and Instrumental Neutron Activation Analysis

Determination of impurities in graphite is very important for its quality control, as their presence even at trace level can affect the performance of graphite in various applications. Graphite with equivalent boron content (EBC) less than 5 mg kg-1 is considered as nuclear grade. Elements with high neutron absorption cross section (boron and rare earths) contribute significantly to EBC. Non-destructive method is preferred as there is no sample processing and probability of loss of volatile elements while digestion. Proton Induced Gamma Ray Emission (PIGE), Instrumental Neutron Activation Analysis (INAA) were utilized for the non- destructive determination of impurities in both nuclear and commercial grade graphite. Low Z elements like Li, B, F, Na, Al and Si were detected in graphite by PIGE whereas Na, K, Sc, Cr, Mn, Fe, Co, Zn, Rb, Zr, Sb, Cs, La, Ce, Nd, Sm, Eu, Tb, Yb, Hf, Ta, Th were determined using INAA. Few elements like Ca, Ti, V, Ni, Sr and Pb remained undetected by both the non-destructive techniques. These elements were determined by Total Reflection X-ray Fluorescence (TXRF) after digestion of the graphite samples by dry ashing. Combinations of these techniques were utilized to get maximum information regarding the impurities present in graphite.

Direct digestion of human scalp hair on the substrate used for total reflection X-ray fluorescence analysis.

It is important to determine the elemental content of scalp hair to evaluate human health and environmental contamination. Here, a new sample preparation method for total reflection X-ray fluorescence analysis was developed by directly digesting the human hair on the sample holder. A human hair sample was subjected to thermal nitric acid treatment for sample digestion and homogenization. The Zn concentration was estimated to be ~ 1.89 × 102μg/g. We can evaluate other elements of human hair by using this method.

Total Reflection X-ray Fluorescence Analysis of Plasma Elements in Autistic Children from India.

Trace elements are essential for the human body's various physiological processes but if they are present in higher concentration, these elements turn to be toxic and cause adverse effect on physiological processes. Similarly, deficiency of these essential elements also affects physiological processes and leads to abnormal metabolic activities. There is a lot of interest in recent years to know the mystery behind the involvement of trace elements in the metabolic activities of autistic children suspecting that it may be a risk factor in the aetiology of autism. The present study aims to analyse the plasma trace elements in autistic children using the total reflection X-ray fluorescence (TXRF) technique. Plasma samples from 70 autistic children (mean age: 11.5 ± 3.1) were analysed with 70 age- and sex-matched healthy children as controls (mean age: 12 ± 2.5). TXRF analysis revealed the higher concentration of copper (1227.8 ± 17.8), chromium (7.1 ± 2.5), bromine (2695.1 ± 24) and arsenic (126.3 ± 10) and lower concentration of potassium (440.1 ± 25), iron (1039.6 ± 28), zinc (635.7 ± 21), selenium (52.3 ± 8.5), rubidium (1528.9 ± 28) and molybdenum (162,800.8 ± 14) elements in the plasma of autistic children in comparison to healthy controls. Findings of the first study from India suggest these altered concentrations in elements in autistic children over normal healthy children affect the physiological processes and metabolism. Further studies are needed to clarify the association between the altered element concentration and physiology of autism in the North Karnataka population in India.

Written in ink: Elemental signatures in octopus ink successfully trace geographical origin

In recent years, validation of seafood authenticity and provenance has attracted the attention of authorities and consumers. Increasing levels of food fraud has raised awareness regarding seafood traceability, especially in highly valuable and highly consumed seafood products, such as the common octopus (Octopus vulgaris). Seafood traceability studies based on trace element fingerprinting generally focus on muscle tissues or carbonate structures whilst the ink fluid has been overlooked. Untargeted multi-element Total Reflection X-ray Fluorescence (TXRF) analysis of O. vulgaris ink successfully discriminated four collection areas [91.2 % and 84.1 % using Variable Importance in Projection Partial Least-Squares Discriminant Analysis (VIP-PLS-DA) and Linear Discriminant Analysis (LDA), respectively] along the mainland Portuguese coast (ca. 900 km coast in the Northeast Atlantic). Arsenic, Pb, Na, Sr and Rb were highlighted as elements with higher contributions for sample discrimination between the four considered capture areas. Regarding food safety, it is important to note that some ink samples Cu, Mn and Pb concentrations exceeded human consumption recommended values. Thus, the results show that untargeted TXRF spectroscopy analysis of O. vulgaris ink is a reliable tool for disentangling the geographical origin of the octopus, as well as to inform about the food safety of octopus ink.