Multi-element analysis of vegetal foodstuff by means of low power total reflection X-ray fluorescence (TXRF) spectrometry

Confocal micro-X-ray fluorescence and total reflection X-ray fluorescence analyses of Ryugu sample in a laboratory environment

This study analyzed Ryugu samples utilizing confocal micro-X-ray fluorescence (CM-XRF) and total reflection X-ray fluorescence (TXRF), in which information of elemental mapping as well as the content of trace elements could be obtained separately, and respectively. In CM-XRF, polycapillary lenses are placed in front of the X-ray tube and detector, and elemental information in the overlapping region of both focus points was obtained. Three-dimensional elemental distributions could be obtained by scanning a sample; the Ryugu sample was placed on an Al plate with one center, and the images of Fe, Ni, Cr, and Ca were obtained. The outlines of these elements were almost equivalent; however, as the energy of Ca Kα was low, its intensity in the elemental mapping was weak. Non-destructive TXRF measurements were performed to measure the trace elements in the Ryugu sample. We then performed quantitative analysis and determined the concentrations of trace elements such as Ga, Ge, and Se. The concentrations of these elements are higher than those in the CI chondrites. Therefore, we verified that the 3D elemental distributions and quantitative measurements in the Ryugu sample were performed without destruction.

Bioanalytical Application of the Total-Reflection X-Ray Fluorescence Spectrometry

This paper briefly overviews the application of total-reflection X-ray fluorescence (TXRF) spectrometry in the biosciences, focusing on key bioanalytical applications. It seeks to review and update the current state of TXRF's use in biomedical, biochemical, and pharmacological research. The review highlights relevant works in the field, summarising past achievements and incorporating the latest developments. The goal is to demonstrate how the analytical application of TXRF spectrometry in this area has evolved and what its role is in analysing trace elements and other biomolecules in diverse biological samples and diseases. Physical foundations to understand its analytical power and its comparison with related analytical techniques are presented to gain objective knowledge of the benefits, limitations, and drawbacks that TXRF spectrometry can offer.

Optimization of the suspension procedure by Box-Behnken design for the determination of manganese, iron, and zinc in zeolite clinoptilolite with the TXRF system and insight into its antioxidant properties

Zeolites are a large family of minerals and the most studied is the naturally occurring clinoptilolite. They possess anti-inflammatory, antioxidant, and detoxifying properties which makes them valuable for medicinal use. Element analysis of zeolite's composition is necessary for its precise chemical characterization, and within this work development of a suspension method for the determination of manga nese, iron, and zinc by total reflection X-ray fluorescence spec-trometry (TXRF) was presented. The Box-Behnken design based on the response surface methodology was applied to determine the optimal sample preparation conditions. The significant variables such as sample amount, volume deposition, and dispersant were selected as critical variables. Based on the results obtained, sample suspensions were prepared by weighing 10 mg of the sample and adding 1 mL of 5 % Triton X-100 with 10 mL Ga as internal standard and deposition volume was set at 10 mL. The results obtained with TXRF were comparable with those obtained with the FAAS method, indicating that this technique can be used instead of the conventional methods. Using the best analytical conditions, the limits of detection for trace elements were in the range of 0.2-0.6 mg kg-1. Trueness and precision of the results, evaluated by CRM sample analysis, were in most cases acceptable with recoveries values in the range of 104.9-111.4 % and relative standard deviations of 2-10 % (. = 6). Zeolites showed no ability to quench free radicals nor the ability to influence dietary antioxidants.

Total Reflection X-ray Fluorescence Spectrometry: A Comprehensive Review of Critical Components, Analytical Benefits and Practical Applications

Total reflection X-ray fluorescence spectrometry (TXRF) is a pivotal technique in modern atomic spectroscopy, distinguished by its capability for multi-element simultaneous determination, a wide dynamic concentration range, samples do not require acid digestion. Additionally, TXRF exhibits negligible matrix effects when samples are prepared as thin films. Based on these unique features, recent research efforts have increasingly employed laboratory-built TXRF systems for the determination of major and trace elements in various samples. Given the diverse and intricate nature of TXRF systems components, this paper provides an overview of critical components that constitute these systems, compares the influence of various parameters on analytical performance, and offers recommendations for component selection. Additionally, recent applications of laboratory-built TXRF in fields such as environmental monitoring, nuclear energy, and food safety are discussed, with a focus on sample preparation, analyzed elements, and quantitative analysis are presented together with analytical parameters such as detection limits and recoveries. By introducing the instrument components and their practical applications, this paper aims to guide researchers in the construction and optimization of TXRF systems, thereby promoting the advancement of TXRF in future research and practical applications.

A two-way analytical investigation of ancient gold coins: Elemental and colorimetric description of precious materials

The investigation of ancient artifacts is often constrained by their scarce availability and high protection and custody protocols. Among these, coinage represents an especially valuable kind-of-samples given their uniqueness and the subjacent information that is hidden behind their composition. Their analysis are often carried out using non-destructive techniques in order to avoid any alteration of the samples. In the field of Cultural Heritage analysis, smartphone-based methodologies have experienced a significant increase during the last few years, given their wide availability and ability to yield fast results. However, their analytical application demands a thorough and careful tuning during the methodology optimization. In this work, 21 historical gold and golden coins spanning a historical period of more than 2000 years have been analytically investigated. To that end, a two-fold approach has been implemented: first, the elemental composition has been analysed using portable X-ray fluorescence; and second, an innovative smartphone-based imaging method has been applied to measure their colour. Results allowed to describe the coins from their elemental profile, identifying some potentially debased ones, as well as some others not containing any gold. When possible, the results have been compared to previously reported cases, but our samples include some previously unreported cases representing new insights. All in all, this article provides new analytical data on unanalysed unique historical samples, in terms of their elemental profile and colorimetric properties, making use of an innovative, non-invasive nor destructive, fast and affordable colorimetric smartphone-based method to characterise historical coins.

Nutritional, chemical and functional potential of Inga laurina (Fabaceae): A barely used edible species

Inga laurina is a plant species which produces edible fruits, and until now there is little information available concerning its nutritional, chemical and bioactive composition. In this study, we evaluated for the first time the proximate composition and mineral contents in its fruit (peel, pulp and seed), that is the traditionally consumed part. The seeds obtained the highest protein (19.52 g/100 g), carbohydrate (22.5 g/100 g) and mineral contents, mainly Cu, Cr, P, Mn, Se and Zn. The peel and pulp were excellent sources of fiber (4.5 and 11.05 g/100 g) as well as mineral content, with Cr and Cu standing out in the pulp. This study is notably the first to provide a detailed assessment of the nutritional compositions of traditionally consumed and not consumed parts of this fruit. Sensory analysis of the pulp was also performed, which indicated good acceptance. The antioxidant properties were characterized in the fruit, peels and leaves. The ABTS test showed that leaf supernatant hydroethanolic crude extract (EC50 = 2.70 μg/mL) and its corresponding ethyl acetate (EC50 = 1.68 µg/mL) and butanol (EC50 = 2.48 µg/mL) partitions presented higher antioxidant potential compared to the control Ginkgo biloba (EC50 = 12.17 µg/mL). The most active precipitate extract regarding DPPH was from the peel (EC50 = 13.30 μg /mL) and the most active partition was the ethyl acetate (EC50 = 13.37 μg/mL), both with better activity compared to the control Ginkgo biloba (EC50 = 46.97 μg/mL). The ethyl acetate partition (EC50 = 13.45 μg/mL) and butanol partition (EC50 = 7.97 μg/mL) from the leaves showed the highest antioxidant capacity. Thus, extracts and partitions from the peels and leaves were studied from a phytochemical point of view due to presenting the best results for antioxidant capacity. The presence of phenolic compounds such as myricetin-3-O-rhamnopyranoside, myricetin-3-O-(2″-O-galloyl)-rhamnopyranoside and myricetin-3-O-(2″,4″-di-O-galloyl)-arabinopentoside-methyl ether were observed in the leaf crude extract and polar partitions, being reported for the first time in the Inga genus and Fabaceae family. Moreover, quercetin, quercetin-3-O-galatoctoside, quercetin-3-O-rhamnopyranoside, quercetin-3-O-(2″-O-galloyl)-rhamnoside, and quercetin tri-hexose were identified in the peel crude extract and ethyl acetate partition, in which the galloyl derivative of quercetin was identified for the first time in I. laurina fruit peels. GC-MS enabled separating and identifying substances such as palmitic and stearic acids, and ethyl oleate. It is possible to conclude that I. laurina pulp can be a supplementary food as a source of phenolic compounds, and the other organs of the plant (leaves and peel) are rich in flavonoids with great antioxidant capacity, making this species a promising source of antioxidants.

Bioaccessibility, exposure and risk assessment of potentially toxic elements and essential micronutrients in ayurvedic, traditional Chinese and Ghanaian medicines

Potentially toxic constituents in traditional medicines remain a concern due to health risks posed to consumers. Thirty-six traditional medicines (TM) consisting of 14 Indian Ayurvedic Medicines, 11 Chinese Traditional Medicines and eleven Ghanaian Traditional Medicines were evaluated using Total Reflection X-ray Fluorescence Spectrometer (T-XRF) after microwave assisted acid digestion. Physiologically Based Extraction Test (PBET) was used to obtain bioaccessible elemental concentrations. Merck XVI multi-element standard were used to evaluate the accuracy of the analytical method. The concentrations of the elements were quantified in (mg kg-1): Cr (0.01-698), Mn (0.01-1140), Fe (15-73300), Ni (1-1340), Cu (3-8160), Zn (0.01-224). The greatest bioaccessible concentrations of arsenic was 0.80 mg kg-1 and 0.44 mg kg-1 in the gastric and intestinal phases respectively. In order to evaluate the human health risks from ingesting these TM, the Acceptable Daily Intake (ADI) was calculated for each medicine based on element-specific bioaccessibility-adjusted concentrations and results compared with the United States Environmental Protection Agency (USEPA) Reference Dose (RfD) limits. The Acceptable Daily Intake (ADI) values for risks were within the USEPA RfD. Hazard quotients (HQ) of TM were < 1, meaning elemental concentrations do not pose non-carcinogenic risks to adult consumers. In summary the methods applied in the study gives a new insight on human health risks of potentially toxic and essential micronutrients elements in TM.

Trace Element Quantification in Two Algerian Thymes (Thymus algeriensis Boiss & Reut. and Thymus capitatus (L.) Hoffm. & Link) Using EDXRF Spectrometry

In an attempt to know the elemental composition of two endemic Algerian thyme species, we analyzed eleven mineral and trace elements (Br, Ca, Cr, Cu, Fe, K, Mn, Rb, Sr, V, and Zn) in Thymus algeriensis Boiss & Reut. and Thymus capitatus (L.) Hoffm. & Link. These species are commonly used in Algeria as aromatic and medicinal shrubs. The total concentrations of chemical elements were determined by EDXRF spectrometry. The instrument calibration was assessed through the analysis of certified reference material CRM-336 (Lichen) from the IAEA, Vienna, Austria. The results show that the highest concentrations of the micronutrients (Br, Cr, Cu, Mn, Sr, V, and Zn) were registered in T. algeriensis, while the maximum concentrations of Ca, Fe, and the non-essential element, Rb, were found in T. capitatus. Potassium contents were similar in the two species. The concentrations of essential chemical elements in T. algeriensis leaves were found in the following order: K > Ca > Mn > Fe > Zn > Cu > Cr. However, the order of these elements in T. capitatus was Ca > K > Fe > Zn > Mn > Cu > Cr. Principal component analysis (PCA) showed that T. algeriensis was highly associated with Br, Cr, Cu, Mn, Sr, V, and Zn, while T. capitatus was correlated with Ca, Fe, K, and Rb. Dietary element intakes through ingestion of 1 teaspoon of dry powder (~ 10 g) were estimated and compared to recommended daily intakes and permissible limits under FAO/WHO guidelines. In all cases, these estimates were below those levels. These findings can enhance the dissemination of these medicinal plants, which have medicinal and organoleptic properties, and provide an experiment-based guidance to the pharmaceutical and food industries.

TXRF spectral information enhanced by multivariate analysis: A new strategy for food fingerprint

The increased costumers' request of safe and high-quality food products makes food traceability a priority for frauds identification and quality certification. Elemental profiling is one of the strategies used for food traceability, and TXRF spectroscopy is widely used in food analysis even if its potentialities have not been fully investigated. In this work, a new method for food traceability using directly TXRF spectra coupled with multivariate analyses, was tested. Twenty-four different beans' genotypes (Phaseolus vulgaris L.) grown onto two different sites have been studied. After the development of the method for beans' analysis, TXRF spectra were collected and processed with PCA combined with SNV and GLSW filter obtaining a perfect clustering of the seeds according to their geographical origin. Finally, using PLS-DA, beans were correctly classified demonstrating that TXRF spectra can be successfully used as fingerprint for food/seed traceability and that elemental quantification procedure is not necessary to this aim.

X-ray fluorescence spectrometry for environmental analysis: Basic principles, instrumentation, applications and recent trends

In recent years, the conceptual advancement on green analytical chemistry (GAC) has moved in parallel with efforts to incorporate new screening or quantitative low-cost analytical tools to solve analytical problems. In this sense, the role of solid state techniques that allow the non-invasive analysis (or with a minimum sample treatment) of solid samples cannot be neglected. This review describes the basic principles, instrumentation and advances in the application of X-ray fluorescence instrumentation to the environmental sciences research topics, published between 2006 and 2020. Obviously, and because of the enormous number of works that can be found in the literature, it is not possible to exhaustively cover all published articles and the diversity of topics related to the environment in which a solid state technique like XRF has been applied successfully. It is a question of making a compilation of the instrumentation in use, the significant advances in XRF spectrometry and sample treatment strategies to highlight the potential of its implementation for environmental assessment.

Analytical potential of total reflection X-ray fluorescence (TXRF) instrumentation for simple determination of major and trace elements in milk powder samples

In this contribution, the analytical potential of total reflection X-ray fluorescence (TXRF) instrumentation has been evaluated for the determination of major and trace elements in milk powder. TXRF allows the possibility of direct analysis of solid suspensions without the need for a digestion process and therefore it can be a potential analytical candidate for simple and cost-effective analysis. A detailed study to select sample preparation and measurements conditions was carried out. Different quantification approaches (including internal standardization and empirical calibration) were also tested. Finally, the developed TXRF methods (W anode) were validated by a strict comparison with the data from the reference methods on a set of twenty-three samples using robust statistics. Results showed that acceptable results can be obtained for K, Ca, Fe and Zn determination if using adequate calibration approaches. Otherwise, only screening results can be obtained for light elements (P and Cl) in milk powder samples.

Determination of trace elements in placenta by total reflection X-ray fluorescence spectrometry: effects of sampling and sample preparation

Placental elemental composition can serve as an indicator for neonatal health. Medical studies aiming at revealing such cause-and-effect relationships or studies monitoring potential environmental influences consist of large sample series to ensure statistically sufficient data. Several analytical techniques have been used to study trace metals in human placenta. However, most techniques require provision of clear liquid sample solutions and therefore time- and reagent-consuming total digestion of biological tissue is necessary. In total reflection X-ray fluorescence spectrometry (TXRF)-a straightforward multielement analytical technique-in contrast suspensions of minute sample amounts can be analyzed directly. Therefore, herein we report on a valid method to prepare homogenous sample suspensions for sustainable and fast TXRF analysis of large sample series. The optimized method requires only 10 mg of powdered placental tissue and 1 mL nitric acid. Suspensions are readily prepared within 30 min and the found mass fractions of major, minor, and trace elements are in good agreement in comparison to analysis of digests. In addition, possible effects on fixation time and the exact sampling location, i.e., maternal vs. fetal side of the placenta, were studied applying this method. Thereby, significant differences for fetal placenta tissue compared to maternal or intermediate tissue were observed revealing accumulation of trace elements in the fetal side of the placenta. Furthermore, considerable depletion of up to 60% mass fraction with longer fixation duration occurred in particular in fetal placenta tissue. These findings help to understand the large ranges of mass fraction of elements in placenta reported in the literature and at the same time indicate the necessity for more systematic investigation of non-homogenous elements distributed in placenta taking sampling and stabilization methods into account.

Comparison of Maceration and Ultrasonication for Green Extraction of Phenolic Acids from Echinacea purpurea Aerial Parts

Echinacea purpurea is used in herbal medicinal products for the prevention and treatment of the common cold, as well as for skin disorders and minor wounds. In this study, the efficiency of traditional maceration using water and ethanol was compared with the maceration using mixtures of water and glycerol, a non-toxic, biodegradable solvent from renewable sources. It was found that the glycerol-water mixtures were as effective as ethanol/water mixtures for the extraction of caffeic acid derivatives. All the prepared extracts demonstrated notable antiradical properties. Furthermore, an efficient ultrasound-assisted extraction using glycerol-water mixtures was developed using six independent variables. Their levels needed for the maximum extraction of caffeic acid derivatives were as follows: glycerol 90% (m/m), temperature 70 °C, ultrasound power 72 W, time 40 min, and ascorbic acid 0 mg/mL. Under the optimized conditions, ultrasound-assisted extraction was superior to maceration. It achieved significantly higher yields of phenolic acids in shorter extraction time. The presence of zinc in plant material may contribute to the beneficial effects of E. purpurea preparations. Since glycerol is a non-toxic solvent with humectant properties, the prepared extracts can be directly used for the preparation of cosmetics or oral pharmaceutical formulations without the need for solvent removal.

Features of sample preparation techniques in the total-reflection X-ray fluorescence analysis of tea leaves

Tea is a popular drink around the world and contains essential minerals and trace elements for human health. In this study, the analytical capabilities of the total-reflection X-ray fluorescence method (TXRF) were considered for the analysis of tea. Different sample preparation techniques, e.g. suspension, open vessel acid digestion, and microwave acid digestion were examined. The influence of particle size was investigated in the analysis of the suspension of tea samples. Mass-absorption coefficients for the tea matrix and the critical surface density of the specimen were calculated. The data obtained explain the presence of absorption effects in the determination of P, S, Cl, and K in suspensions. The digestion procedure is chosen as an optimal sample preparation technique for the TXRF analysis of tea. Nineteen real tea samples were analyzed using TXRF. The advantages of TXRF have been presented through the comparison of results with the wavelength-dispersive X-ray fluorescence spectrometry method.

Quantitative analysis of phosphorus and sulfur in vegetation samples at minor and trace levels by EDXRF technique

In this paper, a rapid, simple and reliable quantitative analysis method for Phosphorus and Sulfur in milligram quantities of plant samples by EDXRF has been described. The method uses a thin film sample preparation procedure which includes drying, suspension samples, filtration and pressing of the thin film samples. By measuring four random points of the same thin film sample, the homogenization of thin layer samples was evaluated to ensure the stability of the quantitative analysis results. The calibration curves of P, S, Ca and Fe was established by changing the weight of certified reference materials (CRMs) deposited on the filter. Then, the emission-transmission (E-T) method was used for correcting the matrix absorption effects of phosphorus and sulfur in the thin layer samples. After the correction, the correlation coefficients (R²) of the calibration curves of P and S were higher than 0.99. To evaluate the accuracy of quantitative analysis method, three vegetation verification samples were synthesized by adding the analytical pure powder to CRMs. The quantitative analytical results of EDXRF and ICP-OES were compared to the synthesized value. For P and S elements, the relative error of EDXRF and ICP-OES were 1.2%-6.4% and 4.2 %to 11.4%, respectively.

Possibilities and drawbacks of total reflection X-ray fluorescence spectrometry as a fast, simple and cost-effective technique for multielement analyses of cosmetics

This paper shows a simple, rapid and cost-effective method for multielement analyses of cosmetics. Total reflection X-ray fluorescence spectrometry (TXRF) is used to determine the composition, particularly the presence of potentially toxic elements, of cosmetics. Three sample preparation methods based on suspension preparation were developed for different types of cosmetic samples, e.g. lipsticks, eye shadows and body creams. Limits of detection within the low mg kg^-1 range were obtained and enabled cosmetic screening for compliance with the legal thresholds for some major toxic elements. A good accuracy of the results on a wide range of concentration levels (>10000 mg kg^-1) was found without the need of sample dilution. Results obtained for most elements in the lipstick and cream samples agreed with those obtained by the reference method recommended by the Food and Drug Administration, based on using inductively coupled plasma techniques after microwave digestion. However, for eyeshadow analysis, a more sophisticate approach is needed to improve the analytical results.

Topsoil pollution in highway medians in the State of São Paulo (Brazil): determination of potentially toxic elements using synchrotron radiation total reflection X-ray fluorescence

The presence of metals in vehicle emissions is due to several factors, such as the composition of fuels and lubricating oils, the wear of engine components, and their use in catalytic converters. It is known that the soil near highways is greatly affected by heavy vehicle traffic, since the use of highways is of fundamental importance for the flow of goods and public transport, especially in Brazil, street transport being the main form of transport in the country. Considering the scenario described, the main objective of this study was to monitor the concentration of potentially toxic elements in surface soils located on the medians of the main access highways in the city of Campinas (SP-Brazil) and classify the soils through geoaccumulation index. Using SR-TXRF it was possible to detect and determine the concentrations of 5 elements of toxic-environmental interest (Cr, Ni, Cu, Zn, and Pb) and 11 natural soil composition elements (Al, Si, S, Cl, K, Ca, Ti, Mn, Fe, Rb, and Sr). To evaluate the influence of highway distance on elementary concentrations, ANOVA and Tukey statistical tests were applied. Nickel, Cu, and Zn showed a decrease in their concentrations moving away from the highway, indicating their relation with vehicular emissions. Applying principal components analysis (PCA), it was possible to identify four groups of the quantified elements: those mainly related to the soil itself, those produced by traffic of automotive vehicles, and those emitted by industrial activities.

Total reflection X-ray fluorescence

Total reflection X-ray fluorescence (TXRF) spectrometry is a non-destructive and surface sensitive multi-element analytical method based on energy dispersive X-ray fluorescence spectrometry with detection limits in the lower picogram range. It utilizes the total reflection of the primary X-ray beam at or below the critical angle of incidence. At this angle, the fluorescence intensity is substantially enhanced for samples present as small granular residue or as thin homogenous layer deposited at the surface of a thick substrate. Generally, two types of application exist: micro- and trace-analysis as well as surface and thin-layer analysis. For micro- and trace-analysis, a small amount of the solid or liquid sample is deposited on an optically flat substrate, typically quartz or polycarbonate. The dried residue is analyzed at a fixed angle setting slightly below the critical angle. Quantification is carried out by means of internal standardization. For surface and thin-layer analysis, the surface of an optically flat substrate is scanned. Variations of the incident angle of the primary X-ray beam provide information about the type and sometimes also the amount of material present at or slightly below the surface of the substrate. Major fields of application are environmental samples, biological tissues, objects of cultural heritage, semiconductors and thin-layered materials and films.

In situ fast analysis of cadmium in rice by diluted acid extraction-anodic stripping voltammetry

In China, the production has not realized intensive cultivation and the problem of cadmium (Cd)-contaminated rice is salient, so it is important to classify rice with different degrees of Cd pollution by rapid detection method in situ. This paper established a method with a combination of dilute acid extraction pretreatment and electrochemical devices. Cd was extracted from rice using 3% HCl for 5 min. A standard curve was obtained based on a certified reference material in the rice matrix with different concentrations of Cd, which was fitted with the Cd concentration (μg kg^-1) against the stripping peak current value (μA), and the linear correlation coefficient was 0.9997. To analyze the applicability of the method, three factors including substrate diluents, particle diameter of the sample, and stability towards the method were evaluated. The limit of detection (LOD) was 2.02 μg kg^-1, and the repeatability and accuracy were satisfactory. Cd was determined in 142 samples collected from three major grain-producing provinces of China, and the results have good consistence with the microwave digestion-ICP-MS method. The developed method combined dilute acid extraction with a matrix matching standard curve in ASV for the first time, and it was significantly satisfactory for the detection requirements in China.

Radionuclide X-ray fluorescence spectrometry of medical plant samples

The method of samples processing and subsequent their analysis using Radionuclide X-ray Fluorescence Spectrometry for medical plant samples and drugs has been developed. Technical aspects of the measurement such as mutual geometrical arrangement of tablets (of various size and mass), semiconductor Si/Li detector and the primary source of radiation, 238Pu, are discussed. Technique of Radionuclide X-ray Fluorescence Spectrometry (RXFS) has been applied on samples of medical products and medicines used to treat liver diseases. Medicinal herbs, teas in infusion bags and the drug from this group, were analysed in the solid state (in the form of tablets) or as the leachate, applied to the ion exchanger resin. Chelating Extraction Disks EmporeTM have proven the ability to extract elements from liquid samples under certain conditions and thus to prepare samples for RXFS analysis and evaluation. To ensure correct results, an optimal pH environment has been found. The detection limits of selected elements (Cr, Mn, Fe, Ni, Cu, Zn and Pb) have been calculated for both solid and liquid state samples. Standard addition method and calibration curve parameters have been used to evaluate the concentration of each element in studied samples. Determined concentrations of the examined elements were compared with permissible contaminant limits for the relevant food law in Slovak Republic.

Insights on limits of detection, precision and accuracy in TXRF analysis of trace and major elements in environmental solid suspensions

In this work, the analytical capability of the total reflection X-ray fluorescence technique with the S2 PICOFOX spectrometer was investigated. A set of certified reference materials was prepared as solid particulate for TXRF analysis. Experimental data of sensitivity, limits of detection and recovery for many elements were obtained. Good sensitivity and limits of detection with a good recovery range of around 90-110% were achieved. Thus, the TXRF technique exhibits a good analytical potential for its applicability on different materials.

Investigation of Trace Element Content in the Seeds, Pulp, and Peel of Mashui Oranges Using Microwave Digestion and ICP-MS Analysis

Fresh Mashui orange samples were pretreated with microwave digestion using an HNO₃-H₂O₂ system. The levels of Mg, K, Ca, Fe, Mn, Cu, Zn, As, Cd, and Pb in the seeds, pulp, and peel were then determined using inductively coupled plasma mass spectrometry (ICP-MS) combined with collision cell technology (CCT) and kinetic energy discrimination (KED). The standard curve coefficient of determinations of the ten tested elements were between 0.9995 and 0.9999. The instrument detection limit was between 0.112 ng/L and 3.05 ng/mL. The method detection limit was between 0.0281 and 763 ng/g. The average recovery rate was between 85.0 and 117%. The current results showed that Mashui oranges are rich in three elements, namely Mg, K, and Ca. The concentrations of K and Ca were significantly higher than that of Mg in the peel. The content of K was the highest in the seeds. Fe, Mn, Cu, and Zn had the second highest concentrations, and Fe was the highest in the seeds, while Cu was the lowest in the peel. As, Cd, and Pb (hazardous elements) had the lowest concentrations of all the tested elements.

Comprehensive approach to the validation of the standard method for total reflection X-ray fluorescence analysis of water

In this work, we present the validation of the chemical method for total reflection X-ray fluorescence (TXRF) analysis of water, proposed as a standard to the International Standard Organization. The complete experimental procedure to define the linear calibration range, elements sensitivities, limits of detection and quantification, precision and accuracy is presented for a commercial TXRF spectrometer equipped with Mo X-ray tube. Least squares linear regression, including all statistical tests is performed separately for each element of interest to extract sensitivities. Relative sensitivities with respect to Ga, as internal standard, are calculated. Accuracy and precision of the quantification procedure using Ga as internal standard is evaluated with reference water samples. A detailed discussion on the calibration procedure and the limitation of the use of this method for quantitative analysis of water is presented.

Elemental analysis of tree leaves by total reflection X-ray fluorescence: New approaches for air quality monitoring

This work shows that total reflection X-ray fluorescence (TXRF) is a fast, easy and successful tool to determine the presence of potentially toxic elements in atmospheric aerosols precipitations on tree leaves. Leaves are collected in eleven parks of different geographical areas of the Brescia city, Northern Italy, for environmental monitoring purposes. Two sample preparation procedures are considered: microwave acid digestion and the novel SMART STORE method for direct analysis. The latter consists in sandwiching a portion of the leaf between two organic foils, metals free, to save it from contamination and material loss. Mass composition of macro, micro and trace elements is calculated for digested samples, while relative elemental amount are obtained from direct analysis. Washed and unwashed leaves have a different composition in terms of trace elements. Differentiation occurs according to Fe, Pb and Cu contributions, considered as most representative of air depositions, and probably related to anthropogenic sources. Direct analysis is more representative of the composition of air precipitations. Advantages and drawbacks of the presented methods of sample preparation and TXRF analysis are discussed. Results demonstrate that TXRF allows to perform accurate and precise quantitative analysis of digested samples. In addition, direct analysis of leaves may be used as a fast and simple method for screening in the nanograms range.