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In order to ensure that byproducts are environmentally friendly and fit for purpose, their chemical composition must be determined, with special attention to elements at trace level. The large variability in the type of matrices demands a versatile analytical technique, compatible with sample preparation methods allowing both fast composition screenings and accurate quantitative analysis. In this work, byproducts derived from carbon-rich matrices, including coal fly ash and activated carbon from coconut and almond shells, were investigated by means of total reflection x-ray spectrometry and different sample preparations. Suspension, acid digestion, solid-liquid extraction and ashing were performed and assessed as to their complexity and detection capabilities, ranging from 0.01 mg/kg to 16 mg/kg, depending on the element and sample preparation. The internal standard quantification with gallium, aided by a variation of the standard additions method to take into account its possible presence in the samples, allowed to determine elements of environmental and technological interest, including K, Ca, Ti, V, Mn, Cr, Ni, Cu, Zn, Ga, As, Sr, Pb. Assets, limits and possible developments are presented and discussed. [Display omitted] • Hazardous and strategic elements were detected in coal fly ash and activated carbon. • Sample treatments were compared as regards complexity and detection capabilities. • An adapted standard additions method aided the quantification by internal standard. • TXRF proved to be a versatile technique to characterize diverse valuable byproducts. [ABSTRACT FROM AUTHOR]

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 C 1 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. [Display omitted] • Ratio map of TXRF net and background intensities was shown. • The effect of the plasma treatment on the glass was confirmed by XPS. • The recovery of TXRF analysis of low-Z element in white wine improved. [ABSTRACT FROM AUTHOR]

The aim of the research presented in this article is to select best internal standard for use in the direct routine analysis of L series elements concentration in water samples by applying the Total Reflection X-ray Fluorescence (TXRF) technique. In the study, aqueous reference materials were used to determine detection limits of the following potentially toxic elements: Pd, Ag, Cd, In, Sn, Sb, Ba, Nd, Gd, Er, Ta, W, Tl, Pb, and Bi. The elements were in the form of: monoelemental, two-elemental (Ba and Ti, W and Cu, Pb and As), and multielemental solutions with different concentrations of elements. The detection limits of chemical elements were analyzed using various internal standards (Co, Ga, Nd, and Sr), and the TXRF spectrometers with the Mo-anode and W-anode X-ray tubes. For the analyzed L series elements, the detection limits, normalized to the same measurement time (t = 1000 s), were calculated. Finally, the internal standards were proposed to analyze the studied elements for two different X-ray sources (the Mo-anode and W-anode X-ray tubes). The detection limits were also discussed with respect to the ISO 20289:2018 standard. Based on the measurements, the relative sensitivities were calculated for each of the applied TXRF spectrometers. [Display omitted] • Internal standard (IS) selection in analyzing of L series elements in water by TXRF. • The detection limits of L series elements were analyzed using Mo-TXRF and W-TXRF. • In analysis various internal standards (Co, Ga, Nd and Sr) were applied. • IS proposed for analysis of the studied elements for two different X-ray sources. • Relative sensitivities calculated for each applied TXRF spectrometer. [ABSTRACT FROM AUTHOR]

The following paper presents statistical analysis of measurement results close to the detection limit of an analytical technique and being random-left censored data. For such observations the measured value is not known precisely but is restricted by the detection limit. In the paper, the idea of random-left censored observations and data analysis are presented generally and next it is shown how to include censored observations into the statistical analysis with the use of available statistical analysis software (survival analysis procedure). Statistical procedure is presented on the examples of the X-ray spectroscopic analysis of element concentrations in medical and biological samples. Censored observations are included in data analysis and quartiles are estimated. Additionally, two- and multigroup comparison is presented for the censored observations. The accuracy of the presented procedure is demonstrated and discussed on the basis of Monte-Carlo simulations. [Display omitted] • X-ray spectroscopic measurement results limited by detection limit (censored data). • Analysis of censored observations with the use of statistical analysis software. • Analysis based on examples of TXRF measurements in medical and biological samples. • Procedure accuracy demonstrated on the basis of Monte-Carlo simulations. [ABSTRACT FROM AUTHOR]

Iodine stands as a vital trace element essential crucial for synthesizing thyroid hormones, which are essential for regulating metabolism and tissue growth. The "gold standard" for assessing iodine status in a population quantifies the iodine content in urine samples and is based on Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). Such method, or methods involving the readings of the Sandell-Kolthoff (S K) reaction, require complex sample preparations and the use of several toxic chemical elements. However, recent studies have shown a strong correlation between urinary iodine content (UIC) and iodine present in saliva. Using Monte Carlo simulations, this paper presents a TXRF-based method to quantify salivary iodine biomarker for assessing and monitoring iodine status. In the theoretical analysis, mono and polychromatic (filtered) excitation sources are considered. The detection and quantification limits of iodine, as well as the calibration curves for mass recovery, used the strong I K α 1 and I K α 2 lines. It was found that the optimal X-ray excitation source energy for iodine detection is 50 keV monochromatic X-rays. In contrast, using simulated spectra from a tungsten anode target, the best result was found at 70 kVp (peak voltage), after filtering the white beam with a copper absorber. Detection limits of iodine are 0.121 ng and 2.292 ng, for mono and polychromatic sources, respectively. The theoretical results of this paper show that TXRF could be a fast, simple and accurate alternative to ICP-MS or S K reaction-based methods. Of clinical significance, quantifying salivary iodine using TXRF to assess and monitor iodine status could be particularly helpful to patients undertaking 131I treatment. In addition, it could be used in epidemiological field studies to determine iodine deficiency/excess in children and pregnant women. [Display omitted] • TXRF based method for quantifying salivary iodine is simulated by Monte Carlo. • Detection limits of 0.121 ng and 2.292 ng, for mono and polychromatic X-ray beams. • TXRF could be a simple and fast alternative to ICP-MS method. • Particularly helpful to assess iodine status of patients undertaking 131I treatment. • Epidemiological field studies of iodine deficiency in children and pregnant women. [ABSTRACT FROM AUTHOR]

A new fundamental parameter model and calculation algorithm is presented for quantitative analysis for total reflection X-ray fluorescence analytical technique. The model takes into consideration the geometrical parameters of the measuring set-up, the energy distribution of the exciter X-ray beam and its incidence angle to the surface of the sample holder. The numerical solution of this new model results the concentration of the sample elements. The system of equations of the fundamental parameter model involves the mathematical description of the excitation process in the sample layer and in the sample holder. The theoretical calibration for the quantitative determination of the sample elements is based on the numerical comparison of the measured and calculated X-ray fluorescence signal of the pure silicon sample holder. For the numerical calculation computer code was created in order to solve numerically the model equations. The whole analytical procedure is a standard-free method. The theoretical model and the complete numerical calculation was tested experimentally with standard solutions of K, Sc, V, Mn, Co, Ni and Cu elements, which were dripped onto high purity silicon wafer and dried before measurement. This standard-free analytical procedure can be utilized in the semiconductor industry and in various total reflection X-ray fluorescence analysis performed for investigations of environmental samples, natural waters, geological substances, foods and drinks. Unlabelled Image • New TXRF FP model for quantitative analysis of contamination on silicon wafer. • XRF signal of the silicon wafer is used to calibrate the quantitative TXRF analysis. • TXRF FP analysis of the contamination layer can be done by angle-scan XRF data. • The solution of the TXRF FP problem does not require application of internal standard. [ABSTRACT FROM AUTHOR]

The purpose of the study was performing a round-robin test for the element analysis of mammalian tissue samples using total reflection X-ray fluorescence (TXRF). To achieve this goal, the selected rat organs (kidney, heart, spleen and lung) were subjected to microwave digestion and, in the liquid form, were sent to four European laboratories participating in the inter-comparison investigation. There, using various commercially available TXRF spectrometers, their elemental composition was determined. The carried inter-laboratory comparisons involved macroelements with the concentration above 1000 μg/g (P, S and K) as well as microelements (Ca) and trace elements (Fe, Cu, Zn and Se) occurring, respectively, in the concentrations of 100–1000 μg/g and below 100 μg/g. The validation parameters such as the detection limits of the examined elements as well as the intra-day and inter-day precision were determined. To verify the variation in the results acquired in participating laboratories, for all measured elements, the inter-laboratory precision was evaluated. The data obtained by TXRF were also compared with the ones resulting from ICP-MS (Se) and ICP-OES analysis (P, S, K, Ca, Fe, Cu and Zn). The results obtained as part of the study confirmed the high usefulness of the TXRF method in the elemental analysis of animal tissues. As expected, the best results in terms of the examined validation parameters were obtained for elements with higher atomic numbers (Fe, Cu, Zn and Se). For these analytes, the round-robin test confirmed a good accuracy (around 100% for Fe, Cu, Zn) and precision (intra-day <6%, inter-day <12% and inter-laboratory <12%) what supports the use of TXRF for their determination in the mammalian tissue samples. The obtained results allowed, moreover, to indicate potential issues that require resolving in order to increase the usefulness of the method in case of the analysis of light elements such as P, S or K. It is worth mentioning here, inter alia , the improvement of the sample preparation procedures aiming at the reduction of self-absorption in its dried residue, optimization and/or unification of the sensitivity calibration and the spectra fitting procedures in particular laboratories. [Display omitted] • First round-robin test of the element analysis of rat tissues carried out using TXRF. • Four European laboratories participated in the inter-comparison investigation. • Concentrations of macro-, micro- and trace elements were determined in the samples. • Detection limits of elements, precisions and trueness were evaluated. • Round-robin test confirmed a good accuracy and precisions for Fe, Cu, Zn and Se. [ABSTRACT FROM AUTHOR]

In the present contribution, a simple and inexpensive method for the determination of hexavalent chromium in aqueous solutions was developed. The analytical methodology consists of the combined use of a low cost Cr(VI) isolation procedure followed by the analysis using total reflection X-ray spectrometry (TXRF). The liquid-liquid microextraction procedure (LLME) used is based on the formation of an ion-pair between the cationic part of the surfactant cetyltrimethylammonium bromide (CTAB) and the corresponding anionic Cr(VI) species, which is extracted in few microliters of chloroform. TXRF analysis can be performed directly by deposition of 15 μL of the preconcentrated sample on a sample carrier, without any additional sample treatment. Experimental parameters affecting Cr(VI) extraction and TXRF analysis were studied in detail. Under optimum conditions, a good linearity was obtained in the range of 5–5000 μg/L with a limit of detection for hexavalent chromium of 0.9 μg/L. This fact opens the possibility of Cr determination in aqueous samples characterized by different concentration levels. The methodology was successfully applied for the determination of Cr(VI) species in different type of water matrices (tap, well, river and sea water) as well as industrial aqueous samples including in industrial waste water from a galvanic industry and aqueous clinker extracts. For comparison purposes, the determination of Cr(VI) in industrial samples was also carried out by using the colorimetric method EPA Method 7196. [Display omitted] • Simple and inexpensive method for Cr (VI) determination in aqueous samples. • Combined use of microextraction using a cationic surfactant and TXRF analysis. • Good linearity (5–5000 μg/L) with a limit of detection of 0.9 μg/L Cr (VI). • Application to water samples as well as industrial waste waters and aqueous extracts. [ABSTRACT FROM AUTHOR]

A systematic study, to assess the variations in the intensity ratios of uranium M and L X-ray lines, was carried out using Total reflection X-Ray Fluorescence (TXRF) spectrometry. In order to establish a co-relation between the variations in the intensity ratios of uranium and its oxidation state, various compounds of uranium having oxidation states of 0, +4, mixed oxide and + 6 were prepared by solid state route. Uranyl nitrate solution was prepared by dissolving powders of U 3 O 8 in nitric acid. The U M lines were excited using monochromatised Cr Kα and the U L lines were excited using monochromatised Rh Kα excitation source. The M- and L- X-ray lines of U were measured using a Silicon Drift Detector (SDD) with a special ultrathin polymer entrance window, AP 3.3, of 300 nm thickness. The intensity ratios of U M lines (Mζ, Mβ and Mγ) with respect to U Mα and U L lines (L l , Lβ and Lη) with respect to Lα were determined experimentally in different compounds of U. Statistical evaluations showed a significant difference in the mean values of the intensity ratios of different oxidation states in uranium. [Display omitted] • Establish co-relation between changes in intensity ratios and oxidation states. • Direct TXRF method for assessment of variations in intensity ratios of U X- rays. • An important application for expansion of XRF for speciation studies. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Direct TXRF determination of S, Fe, Cu, Ni in sulfide ores. • Suspension preparation was optimized using the wet grinding procedure. • Particle size of samples was decreased to <6 μm. • Three quantification approaches were compared. [ABSTRACT FROM AUTHOR]

Elemental content plays an important role in biological processes, and so, the multielemental analysis of human tissue samples is required in biomedical research. Still, the small amount of available biological samples and the adipose content of the samples can be major setbacks for the accurate determination of elemental content. In this study, we explored the potential of several analytical approaches combined with total reflection X-ray fluorescence spectrometry (TXRF) for multielemental analysis of human tissues with different adipose content (colon, heart, liver, lung, muscle, intestine, skin, stomach, uterus, bladder and aorta). The capabilities and limitations of different sample treatment procedures (suspension and acidic digestion) and two TXRF systems with different anode configurations (Mo and W X-ray tubes) have been evaluated for such purpose. Results showed that for tissues with a higher fat content (e.g., skin, and intestine) the best strategy was the acidic digestion of the sample before TXRF analysis. However, for other tissues, acceptable results were obtained by suspending 20 mg of powdered material in 1 mL of 2 M nitric acid. A further enhancement of the limits of detection and accuracy of the results was achieved if using Mo-TXRF systems, especially for the determination of low Z elements (e.g., K, and Ca) and of elements present at low concentrations (e.g., Cu) in the human tissues. Finally, results by TXRF analysis were compared with those obtained with μ-EDXRF and ICP-OES, and a good agreement was obtained. [Display omitted] • Good quantitative compromise between techniques for medium-Z elements. • Gauging adipose content through EDXRF for decision-making in TXRF sample preparation. • Tissues with high adipose content require sample digestion procedures. [ABSTRACT FROM AUTHOR]

This study addresses the problem of simultaneous quantitative analysis of six lanthanides (Ce, Pr, Nd, Sm, Eu, Gd) in mixed solutions by two different X-ray fluorescence techniques: energy-dispersive (EDX) and total reflection (TXRF). Concentration of each lanthanide was varied in the range 10 − 6 –10 − 3 mol/L, low values being around the detection limit of the method. This resulted in XRF spectra with very poor signal to noise ratio and overlapping bands in case of EDX, while only the latter problem was observed for TXRF. It was shown that ordinary least squares approach in numerical calibration fails to provide for reasonable precision in quantification of individual lanthanides. Partial least squares (PLS) regression was able to circumvent spectral inferiorities and yielded adequate calibration models for both techniques with RMSEP (root mean squared error of prediction) values around 10 − 5 mol/L. It was demonstrated that comparatively simple and inexpensive EDX method is capable of ensuring the similar precision to more sophisticated TXRF, when the spectra are treated by PLS. [ABSTRACT FROM AUTHOR]

Simultaneous determination of trace and ultra-trace noble metal (NM) contents is a challenging analytical problem. Quantification of NMs in a solid sorbent phase by total reflection X-ray fluorescence (TXRF) was propounded to exclude the problematic stage of analytes desorption. In this study, line overlapping and spectra processing were discussed, theoretical upper limit of area-related mass of the sorbent on a reflector was evaluated, and different quantification procedures were compared. A procedure for the simultaneous determination of Os, Ir, Pt and Au in the solid sorbent phase was developed. This procedure includes sorption of NMs from a diluted solution of a digested sample, TXRF determination of analytes directly in the sorbent phase and data processing using empirical calibration or multivariate regression algorithms (principal component regression, projection on latent structures or partial least squares regression). The procedure allows determining Os, Ir, Pt, Au with a relative error of 15%. Calculated limits of quantification (LOQ) for rocks, considering our sample decomposition procedure, were equal to 0.43, 0.39, 0.43 and 0.31 μg g−1 for Os, Ir, Pt and Au, respectively. The procedure was verified using certificated reference materials and ICP-MS as a reference method. [Display omitted] • The upper limit of area-related mass of the sorbent on carrier has been estimated. • Algorithms of data processing, taking into account overlaps has been proposed. • Os, Ir, Pt and Au were simultaneous determined in solid sorbent phase by TXRF. • The LOQs of noble metals were 0.31–0.43 μg g−1 in the analysis of solid rock sample. [ABSTRACT FROM AUTHOR]

The interactions of gold nanoparticles (AuNPs) with blood represents the first systemic clearance barrier that these particles face in-vivo. Assessment of this interaction is of particular interest in evaluating the efficacy and kinetics of AuNP delivery in various tissues or organs. Total reflection X-ray fluorescence (TXRF) spectroscopy offers multielemental quantification of trace-level concentrations through internal standardization. In this work, we investigate different sample preparation procedures to determine an appropriate method that would allow accurate quantification of AuNPs in blood matrix. Whole blood, plasma and red blood cells samples were doped with La internal standard and certified Au solution. The samples were prepared as is and diluted with water in ratios of 1:1, 1:5 and 1:10. In order to extend the investigation to AuNPs, samples were also doped with 10 nm reference material AuNPs and diluted with aqua regia in ratios of 1:1, 1:5, 1:10. Our results demonstrate that near 100% recovery of Au concentration can be obtained with the appropriate dilutant and dilution ratio. This work facilitates TXRF's transition into AuNP research as it offers an easy-to-use analytical toolbox that can accurately quantify AuNPs in blood. [Display omitted] • Blood represents the first clearance barrier gold nanoparticles (AuNPs) face. • Quantification of AuNPs can offer insight into biodistribution and delivery. • Reference AuNPs in whole blood, plasma and red blood cells were measured with TXRF. • A 1:1 dilution can obtain accurate AuNP quantification in whole blood and plasma. • Red blood cells samples require a 1:5 dilution for accurate quantification. [ABSTRACT FROM AUTHOR]

As the ratio of phosphorus and sulfur in proteins allows the determination of the phosphorylation degree in proteins, the absolute determination of phosphorus and sulfur in organic samples is of growing interest. While it takes some effort to quantify phosphorus and sulfur with inductively coupled quadrupole plasma mass spectrometry (ICP-QMS), total reflection X-ray fluorescence analysis (TXRF) allows easy quantification. In the presented work, the low Z TXRF spectrometer at the Atominstitut was used to analyze phosphorus and sulfur in proteins. Although the preparation of the protein samples proved to be more difficult than originally expected, it could be shown that TXRF is well suited for the determination of P and S in proteins. The obtained lower limits of detection (LLD) for P and S in proteins were extrapolated for 1000s and were 34 pg and 19 pg, respectively. The importance of height scans for each sample to exclude heterogeneities was demonstrated. [ABSTRACT FROM AUTHOR]

Hafnium is a very valuable metal having many applications which require it to be free from impurities. It does not exist freely in the earth crust and is found to be associated with zirconium ores. The raffinate of Zr purification process is one of the sources for obtaining Hf. Accurate analysis of Hf in presence of Zr is essential for such recovery processes. A Total reflection X-ray Fluorescence (TXRF) method for chemical characterization of Hf containing solution samples, obtained during the various steps of recovery process of hafnium nitrate from the Zr purification process, was developed. The finally obtained solid HfO 2 samples were also characterised by TXRF directly without any dissolution. The TXRF results obtained were compared with Inductively Coupled Plasma- Optical Emission Spectrometry (ICP-OES) results for solution samples and were found to be in good agreement. The TXRF method developed has an added advantage that it can analyse the solid samples directly without any dissolution, in addition to requirement of small amount of samples (ng level), economical, fast and no requirement of matrix matched standards. [Display omitted] • Compositional characterization of Hf & Zr in raffinate of Zr purification process. • A simple & direct TXRF method for intermediate solution & final solid samples. • Highly suitable for the routine analysis of samples produced on plant scale. [ABSTRACT FROM AUTHOR]

Sixty-two subjects (31 men with colon cancer) participated in this study. The analysis of elements in the nails was performed by total reflection X-ray fluorescence (TXRF) technique. The results showed that fifteen elements were quantified, including the following: S, P, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, and Br. We have found that there were significant differences in the concentrations of elements Ca, Cr, Fe, Cu, Zn, As, and Se between normal subjects and men with colon cancer (p < 0.05). We conclude that TXRF is a technique suitable for elemental analysis in human nail samples. The concentration of elements Ca, Cr, Fe, Cu, Zn, As, and Se could be among the factors used for the diagnosis of colon cancer risk in men. [Display omitted] • The study was conducted on nail samples collected from 62 men dividing into healthy and colon cancel groups. • Total reflection X-ray fluorescence (TXRF) technique was successfully used for elemental analysis in nail sample. • The elements, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, and Br, were detected and analysed. • The elements Ca, Cr, Fe, Cu, Zn, As, and Se were found to have good correlation with colon cancer. [ABSTRACT FROM AUTHOR]

High purity quartz was analyzed using Total Reflection X-Ray Fluorescence (TXRF) spectrometry, during our participation in proficiency testing programme. The sample was digested in HF-HNO 3 medium and the silica matrix was removed as silicon tetra fluoride by evaporation and repeated treatments with HNO 3. Trace metallic impurities viz. K, Ca, Ti and Fe were quantified via the internal standard (using Ga) method in TXRF spectrometry. The z-score, zeta score and quality control sample analysis revealed the accuracy of the present determinations for all the analytes. Combined uncertainty for the measurement was evaluated through the bottom-up approach. Relative sensitivity of the TXRF spectrometer for the analyte with respect to the internal standard was found to hold the highest share of uncertainty. Detection limits for both the process blank and sample solutions were compared. Detection limits in the sample solutions were 1.86, 0.95, 0.94 and 0.30 mg kg−1 for K, Ca, Ti and Fe respectively. These studies brought out the importance of appropriate concentration of standard solutions for calibration and sensitivity measurements of the spectrometer, in addition to the quality of reference standard solution, for ensuring accuracy of the results. [Display omitted] • Trace impurities in quartz, viz. K, Ca, Ti and Fe were quantified by TXRF. • The z-score, ζ-score and QC analysis established the accuracy of results. • Sensitivity and quality of internal standard affect the accuracy of results. • Using the combined uncertainty, homogeneity for 0.5 g sample was ascertained. • Relative sensitivity of the instrument holds the highest share of uncertainty. [ABSTRACT FROM AUTHOR]

The goal of this study was to check the repeatability of changes of elemental composition of tissues introduced by formalin fixation followed by paraffin embedding (FFPE) – standard processing protocol used in histopathology. To achieve that goal two series of ten samples of quasi-homogeneous swine liver samples – lyophilised and FFPE processed – were compared in terms of statistical dispersion of their elemental concentrations. Total Reflection X-Ray Fluorescence (TXRF) was used for quantification of K, Ca, Mn, Fe, Cu, Zn, Se Br, Rb and Sr in samples after their acid digestion. It has been shown that relative standard deviation introduced by the statistical dispersion of the FFPE processing typically does not exceed 30% which may open up the possibility of analysis of large population of archival tissues. Unlabelled Image • Comparison of formalin-fixed paraffin embedded and lyophilized swine liver tissue. • Evaluation of repeatability of changes of elemental composition introduced by processing. • Comparison of dispersion of results for lyophilized and processed samples. [ABSTRACT FROM AUTHOR]

The analysis of uranium in environmental samples, quantified using total reflection X-ray fluorescence (TXRF) analysis, would be adversely affected by the presence of rubidium and strontium in larger amounts than uranium as coexisting elements. This is because the U Lα line at 13.61 keV is close to the Rb Kα line at 13.40 keV and the Sr Kα line at 14.17 keV. Using the U Lβ 1 line (instead of the U Lα line), which does not overlap with the peaks of coexisting elements, we will be able to avoid these adverse effects. Since there is no TXRF device that can perform a quantitative analysis of uranium by using the U Lβ 1 line, the following modifications were made to the existing device with the intention of rapid on-site analysis. The X-ray tube of the new device has a silver anode instead of a tungsten anode, and the sensitive area of the detector was expanded. In addition, the mechanism for adjusting the position of the sample stage was changed from manual to computerized control. These changes made it possible to screen uranium in environmental samples rapidly on site without chemical separation. Unlabelled Image • A portable TXRF device was modified. • Ag anode X-ray tube enabled evaluation of uranium using the U Lβ 1 line. • An SDD detector with a large X-ray receiving area eliminates the internal standard. • The electric Z stage facilitated adjustment from outside the chamber. [ABSTRACT FROM AUTHOR]

Mercury compounds like mercury chloride (HgCl 2) were often used to protect cultural heritage specimens, e.g., herbaria and paintings from damage. Over time, Hg0 is formed by bacterial activity and released into the air. Here we present our study on the performance of different nanoscopic Ag species to collect airborne Hg, which is subsequently analyzed by total reflection X-ray fluorescence (TXRF). We studied silver nanoparticles (AgNPs) of different size, i.e., 10 nm and 100 nm AgNPs(Citrate) and particles with presumably weaker stabilizers, i.e., 10 nm AgNPs(borohydride(BH 4 −)) as well as species from light-exposed (LE) pure aqueous (LE-AgNO 3 (H 2 O)) and ammoniacal silver nitrate solutions (LE-AgNO 3 (NH 3)). Hg capture was highest for the LE-AgNO 3 (NH 3) species with a ratio of Hg/Ag of 0.78 in the amalgam. The performance to capture Hg decreased from LE-AgNO 3 (NH 3) to AgNPs(Citrate) in the following order LE-AgNO 3 (NH 3) > LE-AgNO 3 (H 2 O) > 10 nm AgNPs(BH 4 −) > 10 nm AgNPs(Citrate) > 100 nm AgNPs(Citrate), the latter collected airborne Hg with a ratio of Hg/Ag of 0.0006. The relative standard deviation of the TXRF measurements of Hg collected from a saturated atmosphere (n = 3 and n = 5) was lowest with 9% for LE-AgNO 3 (H 2 O) and highest for the AgNPs(Citrate) with 38%. The AgNPs(BH 4 −) and AgNPs(Citrate) species were also used to study Hg capture from the gas-phase in concentrations between 0.0012 mg/m3 and 0.024 mg/m3 (European Union regulated threshold: 0.02 mg/m3; saturated Hg atmosphere: 13.6 mg/m3 at 20 °C). Detection limits were found to be 0.018 μg/m3 for AgNPs(BH 4 −) and AgNPs(Citrate). Unlabelled Image • Differences in the uptake of gas phase mercury using different silver species. • The performance of AgNPs(BH 4 −)to capture Hg was better than that of AgNPs(Citrate). • Light exposed ammoniacal AgNO 3 species performed better than the other species. • Hg detection limits of 0.018 μg/m3 AgNPs(BH 4 −) and AgNPs(Citrate) were found. [ABSTRACT FROM AUTHOR]

Proper supply of nutrients to plants is mandatory for adequate crop production. Many strategies, such as soil fertilization, nutrient foliar spraying, and seed treatment have been proposed to this goal. Currently, plenty of studies in plant nutrition afford only a low mass of sample for analyses, which is not sufficient for most spectroscopic techniques, including conventional energy dispersive X-ray fluorescence spectrometry (EDXRF). In this context, we developed a new EDXRF method for the determination of nutrients in mass-limited soybean plant tissues. Soybean seeds were treated with different types of Zn suppliers (ZnSO 4 and ZnO nanoparticle sources), sowed, and soybean roots and shoots were sampled two weeks after germination. For EDXRF analysis, 20 mg of samples were suspended in 1 mL of deionized water, and 20 μL of the suspension were dried on a 6 μm polypropylene film in an X-ray cup. External calibration using a set of synthetic aqueous cellulose multielemental standards suspended in 1% Triton X-100 proved to be a good strategy for quantification purposes. The trueness of the proposed method was verified analyzing several plant tissue certified reference materials. Additionally, soybean samples were also analyzed by using a validated total reflection X-ray fluorescence (TXRF) method, and good agreement was found between both analytical approaches. To sum up, the proposed EDXRF thin film method is straightforward and reliable for mass limited vegetal sample multielemental analysis and, additionally, follows the green analytical chemistry postulates. Unlabelled Image • Analytical approach for vegetal (20 mg) mass-limited sample analysis by EDXRF. • Quantification by aqueous multielemental STDs with cellulose and 1% Triton X-100. • Appropriate P, S, K, Ca, Mn and Fe LOQ for vegetal tissue analysis by EDXRF. • Good agreement between EDXRF and TXRF results for soybean root and shoot analyses. [ABSTRACT FROM AUTHOR]

Total Reflection X-Ray Fluorescence spectrometry (TXRF) provides many advantages for metal and metalloid analysis. In general, the sample should be prepared as a thin film. To that end, for the analysis of liquid, suspensions or solids previously digested, a small aliquot of the sample is dropped on the sample carrier (e.g. quartz reflector). However, main inconveniences of this technique are the low sensitivity achieved for certain elements depending on their fluorescence yield (also related with the atomic number and the line series selected for the element quantification), and the high volatility of certain elements and compounds (such as oxides, fluorides, chlorides and hydrides) due to their loss during sample drop evaporation performed in the quartz reflector as a consequence of sample preparation before TXRF analysis. Published papers on this subject are mainly related to mercury, but volatilization losses of selenium, arsenic, lead and cadmium and halogens have also been reported. Different analytical approaches have been developed to improve the sample preparation step so as to avoid losses of volatile elements and compounds before TXRF analysis, which are summarized in this review. These strategies include slurry sampling, amalgamation, complexation, adsorption onto membranes, immobilization on quartz reflectors and more recently approaches using nanomaterials like metallic nanoparticles, carbon dots and graphene that can also preconcentrate target analytes. Potentials and pitfalls of these strategies are discussed in this review, as well as other tentative approaches. Unlabelled Image • Sample pretreatment to avoid element losses by TXRF is reviewed. • Elements prone to be lost by volatilization (especially Hg) are targeted. • Analytical strategies with and without NPs are discussed. • Amalgamation, membrane adsorption, immobilization and complexation are suitable strategies. • Graphene, graphene oxide, carbon nanotubes, Ag and Pd NPs can be used for sorption. [ABSTRACT FROM AUTHOR]

European countries have made progress in reducing particulate air pollution in recent decades being concerned about their heath and climate effect. In addition to determining particulate number size distributions, it is crucial to have a methodology to determine size distribution of elemental concentrations down to the ultrafine size fraction. The present study shows capabilities for combination of May-type cascade impactor sampling and laboratory total-reflection X-ray fluorescence analysis on ambient aerosol samples taken in urban areas of Budapest (Hungary) and Cassino (Italy). In addition, results for a sample collected in Budapest during the fireworks provided for the Hungarian National Day are discussed. The combined novel method is suitable for determining size distributions for major and trace elemental concentrations form ultrafine to coarse particles (70 nm up to 10 μm) in seven size fractions. Moreover, short sampling times (1–4 h) are sufficient for reaching detection limits in the range of 100 pg/m3 for transition metals. The size and time resolution were found to be optimal for identifying pollution episodes with elevated elemental concentrations. The in-the-field analytical applicability of the proposed method for major and trace elements is demonstrated by comparison to elemental size distributions resulted from destructive analytical techniques. Unlabelled Image • Fast and straightforward analytical method needed for atmospheric particle monitoring. • Combination of cascade impactor sampling and total reflection X-ray fluorescence. • Direct analysis of impactor plate of seven size fractions from 70 nm to 9 μm. • Elemental size distribution of aerosol pollution events in urban and industrial area. • New technique will enable on-site diurnal variation study of pollutant sources. [ABSTRACT FROM AUTHOR]

This paper presents the assessment of a direct method to measure and analyse Pb in air particulate matter (PM) collected on polytetrafluoroethylene (PTFE) filtering membranes prepared by the SMART STORE® procedure. The suitability of grazing incidence X-ray fluorescence technique is verified on a set of continuous and conformal thin film samples created by atomic layer deposition. Different scans changing the angles of incidence are performed and the fluorescence intensity of thin films on PTFE substrate compared with that obtained by similar thin films deposited on Si wafer substrates. The effects of sample preparation, constraints, and limitations of the experimental setup are discussed. The results obtained by three commercial total reflection X-ray fluorescence spectrometers, equipped with Mo or Rh X-ray tubes, are compared. Reference samples with different Pb content are used to define the best measurement conditions, corresponding to the maximum fluorescence intensity. The precision is evaluated in terms of relative standard deviation of the net intensity, taking into account the homogeneity of the PM samples and hardware contributions to the errors. The calibration curves are built on the basis of mono- and multi-elemental Pb loaded PTFE reference samples. The analytical parameters, namely linear calibration and determination range, limits of detection, and quantification, are determined. Unlabelled Image • Assessment of a direct method to measure and analyse Pb in air PM filters by GIXRF. • Thin film model samples and novel reference materials on PTFE are analysed. • Effects of sample preparation and limitations of the experimental setup are discussed. • Comparison of three commercial TXRF spectrometers is presented. • Suitable measurement conditions are identified and calibration line are built. [ABSTRACT FROM AUTHOR]

Studies involving nanoparticle uptake in cells and tissues are contingent upon adequate methods of quantification. For gold nanoparticles (AuNPs), the quantification of uptake typically relies on inductively coupled plasma (ICP) based techniques which require sample pre-treatment and large sample volume (5–10 ml). To address these shortcomings, a total reflection X-Ray fluorescence (TXRF) spectroscopy-based method was developed to measure uptake of AuNPs in breast (MDA-MB-231) and prostate (PC3) cancer cells without any sample pre-treatment. In order to directly compare the quantification of TXRF and ICP Atomic Emission Spectroscopy (ICP-AES), samples were pre-treated with the most commonly used ICP-AES wet digestion protocol adopted from literature. The accuracy of both spectrometers was assessed by calculating the recovery rate of 10 nm reference material AuNPs in MDA-MB-231 and PC3 cells. TXRF showed analytically acceptable recovery rates of 96.1% and 98.7% for unfiltered MDA-MB-231 and PC3 cells, respectively, while ICP-AES showed low recovery rate of 23.3% and 27.8% for filtered samples. The nearly 80% underestimation by ICP-AES highlights the importance of proper sample pre-treatment for ICP-based measurements. Furthermore, it also has important implications in the clinical translation of AuNPs as knowledge of uptake is required for determining the nanoparticle injected dose. This work demonstrates TXRF's ability to accurately quantify AuNP without ICP-required wet digestion protocols using only 5 μl of sample per reflector, making the technique a suitable alternative to ICP-AES. Unlabelled Image • Clinical translation of gold nanoparticles (AuNP) requires accurate quantification. • AuNP uptake was measured by TXRF and previously published ICP-AES protocols. • TXRF can accurately measure AuNP uptake in breast and prostate cancer cells. • Current ICP-AES sample treatments are underestimating AuNP by nearly 80%. [ABSTRACT FROM AUTHOR]

The presence of elemental impurities in fuels is a key topic with important consequences: they may both adversely affect the performances of engines and contribute to the contamination of the environment, primarily air, but on the long term also waters and soils. Accordingly, the determination of trace elements in fuels is of the utmost importance in several fields, ranging from quality control to regulatory issues (e.g. control of emissions). Traditionally, atomic spectrometric techniques have been employed to this aim: these techniques typically require a pretreatment step involving either sulfate ashing, microwave digestion or dilution in solvents. Here we propose a fast, direct and sensitive method for the quantification of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As and Pb at trace level in light and middle distillates, namely gasoline, racing and jet fuel, by Total Reflection X-Ray Fluorescence (TXRF). A simple sample treatment procedure, based on on-site enrichment, allowed to achieve limits of detection below 1 ng/g. The quantification method by internal standard was assessed and validated by recovery tests: its optimization and limits will be presented and discussed. Unlabelled Image • V,Cr, Mn, Fe, Co, Ni, Cu, Zn, As and Pb were detected in light fuels by TXRF. • On-site enrichment allowed to get detection limits below 1 ng/g. • Detection limit can be controlled by tuning acquisition time and enrichment level. • TXRF efficiently combines easy detection and minimal sample preparation. [ABSTRACT FROM AUTHOR]

Total reflection X-ray fluorescence spectrometry (TXRF) is known as a state-of-the-art and fast-growing analytical technique. The spectral range of TXRF spectrometry encompasses elements from sodium to uranium. The object of this study was to develop, optimize, and validate the analytical method for fluorine in a form of calcium fluoride determination in fluoride fluxes by total reflection X-ray fluorescence spectrometry. The sample was lixiviated in acetic acid, then, the sample was filtered and the sediment and the filter were ignited at 650 °C. A portion of dried and ignited and weighed sample was placed in a plastic centrifuge tube. To this tube Triton X-100, Ga as internal standard and polyvinyl alcohol were added. The accuracy of the element determinations was estimated by comparison between obtained and certified values of the elements determined in the Certified Reference Materials of fluorite (fluorspar). The limit of detection for TXRF measurement is 4.26 μg F · dm−3 whereas the limit of quantification equals 12.78 μg F · dm−3. The variation coefficient that characterized the reproducibility of the measurement equals 16.94%. In addition to this, it was found that the uncertainty of results associated with the sample preparation process for TXRF measurement is negligible, compared to the measurement uncertainty at the measurement stage using TXRF spectrometry. The results of this work demonstrate the acceptable and fully satisfactory validation criteria such as limit of detection and quantification, accuracy, and precision. Unlabelled Image • A methodology for determination of fluorine in a form of calcium fluoride in fluoride fluxes is proposed. • Homogenization helps to diminish particle size, but it is not effective to homogenize samples and improve standard deviation of results. • The uncertainty of results associated with the sample preparation process is negligible, compared to the uncertainty at the measurement stage. • The acceptable and fully satisfactory validation criteria such as limit of detection and quantification, accuracy, and precision. [ABSTRACT FROM AUTHOR]