Application Of X-ray Fluorescence Research Articles

An integration of µXRF and X-ray microdensitometry records in dendrochronology

X-ray based microdensitometry is conventionally used to produce climate-related tree-ring records. Micro X-ray fluorescence (µXRF) applications represent another growing area of interest and opportunities in dendrochronology. This paper demonstrates a method to correctly juxtapose and precisely synchronise the densitometry and µXRF profiles. Among µXRF variables, full fluorescence spectrum (FFS) corresponds distinctly well with the microdensitometry-based wood density variations. Accordingly, the FFS provides the most applicable variable to integrate the µXRF and density profiles. The method proposed here can be used to demonstrate the strength and sign of µXRF variables and wood density relations. Moreover, the µXRF based records can be readily compared to density variables, such as the latewood maximum density, which is demonstrated in this paper.

Investigating the Degradation of Mycenaean Glass Artifacts Using Scientific Methods

Mycenaean vitreous artifacts, such as beads and relief plaques, are highly susceptible to degradation, which can significantly alter their visual characteristics and pose challenges to their taxonomy. The visual manifestation of corrosion on vitreous artifacts, especially glass and faience, has often led to their misclassification, which, in turn, has a significant impact on their interpretation by researchers, often resulting in misleading notions. The present paper constitutes part of an overall study, implemented within the framework of the project, Myc-MVP: Mycenaean Vitreous Production, A Novel Interdisciplinary Approach Towards Resolving Critical Taxonomy Issues, which has employed a combination of established, state-of-the-art scientific methods to analyze and identify the specific compositional changes occurring at different spatial dimensions within surface layers, with the overarching aim of contributing to our understanding of the degradation mechanisms of vitreous artifacts and the relevant implications for the archaeological record. Importantly, these findings will yield useful data in devising strategies for the proper classification, management, and preservation of vitreous artifacts in the future. The present study focuses on investigating the relationship between the compositional changes in a subset of 12 (of the overall 126 objects entailed in the project) corroded vitreous artifacts from Mycenaean contexts in the Aegean and the way these are manifested visually, with the application of X-ray fluorescence and LED microscopy. We aim to decipher the nature of corroded objects with the aid of focused analysis. This study delves into degradation processes in glass artifacts, highlighting preservation variations and environmental influences like burial. Coloration, attributed to copper and cobalt oxide, shows some correlation with preservation quality. These chromophore agents potentially induce thermal stresses and corrosion. The complex interplay between chemical composition, environmental conditions, and preservation status underscores the need for comprehensive research. Analyzing the full artifact set using complementary techniques promises deeper insights for secure material classification and cultural heritage preservation.

Application of X‐ray fluorescence in forensic archeology: A review

AbstractForensic Archeology is the application of techniques and principles of archeology in the pursuit of examining a crime or incident with legal interest. A wide range of analytical studies are employed in examining archeological remains. X‐ray fluorescence (XRF) spectroscopy remains to be one of the most used techniques for rapid examination of trace evidence typically found on an archeological crime scene. Studies of interest generally include finding trace elements from various sources, samples, and different environmental conditions and distinguishing whether a skeletal remains under examination is human, animal, or marine species. The present study has been designed to focus on the application of XRF in archeological and anthropological evidences such as the examination of human skeletal and dental remains, determination of species, examination of soil, ceramics, paintings, coins, and so on. The advantage of XRF as derived from the reported literature is that it is a non‐destructive technique making it ideal for forensic analysis and in situ examination. The study also discusses the factors affecting forensic investigations of archeological evidences and the limitations of XRF.

Evaluation of geomagnetic relative palaeointensity as a chronostratigraphic tool in the Southern Ocean: Refined Plio-/Pleistocene chronology of IODP Site U1533 (Amundsen Sea, West Antarctica)

International Ocean Discovery Program (IODP) Expedition 379 to the Amundsen Sea margin of West Antarctica recovered drill cores at two sites spanning the Latest Miocene–Holocene interval with the aim of reconstructing past West Antarctic Ice Sheet dynamics. The recovered Plio-/Pleistocene sediment sequences offer an opportunity to apply and test different dating approaches in an Antarctic deep-sea drift setting, where the records are nearly continuous and unaffected by scouring of icebergs or grounded ice. Here, through palaeomagnetic analysis of continuous u-channel samples and application of X-ray fluorescence (XRF) scanning, we revise the IODP Exp. 379 Site U1533 age model for the uppermost Pliocene and Pleistocene composite interval (0.0–2.9 Ma). We first refine the magnetostratigraphic age model with high-resolution u-channel analysis and interpreted directional data. Consistent with shipboard results, all major geomagnetic polarity chrons and subchrons are identified in the Pleistocene section. The new high-resolution u-channel dataset also allows us to identify a geomagnetic polarity excursion at ∼884 ka (interpreted as the Kamikatsura excursion) and another excursion at ∼2734 ka with confidence (potentially the Porcupine excursion). Based on the improved polarity stratigraphy, we then develop two new highly resolved age models for Site U1533 using: (i) barium enrichment cycles identified in XRF scanning data, and (ii) geomagnetic relative palaeointensity (RPI). In our first age model, we correlate cyclic variations in sedimentary barium enrichment, inferred to represent changes in export productivity, to glacial‒interglacial cycles of the Lisiecki and Raymo (2005) benthic foraminiferal oxygen isotope (δ18O) stack (LR04). Nearly all Pleistocene Marine Isotope Stages (MIS) are interpreted to be present in the barium enrichment record of Site U1533, assuming simultaneous changes in Antarctic sea-ice extent/local export productivity and global oxygen isotope stratigraphy. We then construct the second, independent age model using the Plio-/Pleistocene RPI record developed for Site U1533, which represents the longest (nearly) continuous RPI record currently available for the Antarctic margin. Comparison of the two, independently derived age models shows a variable offset, on average ± 12 kyr, with the RPI-based ages consistently older than the barium-based ages in the interval from 1.9 to 2.9 Ma and then consistently younger from 0.0 to 1.9 Ma. We interpret these offsets to result from a combination of lock-in depth effects in the younger interval (due to the relatively low sedimentation rates at this site, ∼2 cm/kyr), temporal offsets between global δ18O changes in the deep ocean and productivity response on the Antarctic margin, and/or systematic miscorrelation in the construction of the two age models. Finally, we construct a hybrid age model for the Pleistocene section of Site U1533 by combining a mixture of RPI- and barium-based age tie points that are deemed to be robust. The Site U1533 RPI record is then used, together with other Southern Ocean RPI records, to construct an Antarctic RPI stack (designated as ‘ANT-1600’) for the interval 0.0–1.6 Ma. Although sedimentation rates at two-thirds of the sites selected for the stack are lower than 10 cm/kyr, the new ANT-1600 stack is strongly coherent with the SINT-2000 RPI stack (Valet et al., 2005) on time scales of ∼20–200 kyr, allowing for its use as a regional RPI reference curve in future studies. Overall, we demonstrate that RPI at Antarctic margin/Southern Ocean sites provides a viable and valuable independent dating method for application to Plio-/Pleistocene Antarctic sediments.

Micro X-ray fluorescence device based on monocapillary ellipsoidal lens for thin film thickness measurement

X-ray fluorescence (XRF) is a crucial non-destructive technique for determining the thickness of thin films or coating materials to ensure their optimal performance. In order to further expand the application of XRF in thin film thickness analysis, we have developed an inner-wall coated elliptical monocapillary X-ray lens (EMXRL), which has a larger acceptance angle and higher utilization efficiency for light sources compared to traditional inner-wall uncoated EMXRL. In addition, we have built a laboratory micro-X-ray fluorescence (Micro-XRF) thickness measurement device based on coated EMXRL. Compared to common XRF devices, it has a smaller X-ray spot size and higher intensity gain, resulting in smaller spatial resolution and higher detection efficiency in XRF thickness measurement applications. We established a standard curve in the range from 0.85μm to 56.5μm for measuring the thickness of Cu coating on silicon using this Micro-XRF device. The experimental results show that the micro-area thickness measurement device, based on the standard curve method, can measure the thickness of Cu coatings from 0.85μm to about 30.00μm with a relative deviation of about 3%. Within the thickness range from about 30.0μm to 56.5μm, the relative deviation of the measured thickness increased and was larger than 5%. This larger relative deviation mainly resulted from the greater absorption from the thicker coating. Furthermore, We used the device to perform mapping scans on scratched areas of Cu-plated circuit board to verify its usefulness. The results show that the device has the advantages of simplicity and speed, and has potential applications in fields such as semiconductors.

Portable x‐ray fluorescence as a tool for assessing electric marks in forensic evaluation

AbstractPortable x‐ray fluorescence (XRF) is a reliable, rapid and noninvasive technique. Recently, it has been used in a wide variety of fields where the sample must still be available after examination or when qualitative information on chemical composition is needed quickly to perform more detailed studies. These properties also make it suitable for forensic investigations, as shown by some recent reports. In the present work, a systematic evaluation of metal micro traces in electric marks was performed in a case of death by electrocution (high‐voltage current). The results are promising, as XRF has been shown to be a suitable tool not only for skin fragments but also for graphite adhesive tapes placed on the body skin areas of forensic interest and then analyzed. The latter finding proves that skin samples at autopsy are not the only valuable sampling method, thus paving the way for the application of XRF in the diagnosis of electrical injuries in living individuals as well.

Evaluating the Application of Portable Handheld X-ray Fluorescence (XRF) Scanner for Determining Seafood Provenance: A Case Study on Penaeus monodon.

Seafood elemental profiling (SEP) is the quantification of a range of elements in seafood products and may serve in addressing questions of seafood provenance and quality. Traditional methods for analyzing soft tissue present several limitations for the industry-level use of SEP. Portable handheld X-ray fluorescence (pXRF) analysis is a promising alternative to conventional methods; however, its application for biological analysis has not been fully established. Intact giant tiger prawn (Penaeus monodon) abdomens were analyzed with a Vanta M series XRF portable analyzer following a novel soft tissue protocol. Exploratory statistics (principal component analysis, nonmetric multidimensional scaling, and canonical discriminant analysis), as well as random forest models, have been implemented with pXRF profiles, yielding 81% accuracy when assigning the geographical origin of P. monodon. The results of this study highlight that SEP via pXRF is a viable industry-level analysis, and its application will depend on improved instrument calibration to account for fluctuating wetness factors that are influenced by cooking, storage, and other pre- and post-harvest treatments.

The Application of Portable X-ray Fluorescence (pXRF) for Elemental Analysis of Sediment Samples in the Laboratory and Its Influencing Factors

Several techniques, such as chemical methods and inductively coupled plasma mass spectrometry (ICP-MS), are available to accurately determine element content. However, they are time-consuming, labor-intensive, or expensive. Portable X-ray fluorescence spectrometry (pXRF) can be applied in various scenarios, with significantly higher efficiency and cost-effectiveness than laboratory methods. However, it also has limitations such as lower detection capability, relatively high detection limits, and lower accuracy than laboratory methods. In this study, we focused on applying pXRF to determine the elemental content of sediment samples and investigate its use in mineral exploration. A variety of factors influencing the results of pXRF analysis were analyzed. Our results showed that pXRF could detect more than 30 elements in stream sediments. The reliability of pXRF’s measurements was affected by factors such as the kind of element, sediment particle size, sample grinding treatment, count time, averaged element content, standard deviation of content, and range of content variation. The combination of pXRF analysis and laboratory analysis of partial samples is adequate for establishing a multi-element content inference equation. With this equation, it is possible to effectively infer the content gradient of elements, which will provide valuable support for mineral resource exploration.

Resolution-enhanced X-ray fluorescence microscopy via deep residual networks

Multimodal hard X-ray scanning probe microscopy has been extensively used to study functional materials providing multiple contrast mechanisms. For instance, combining ptychography with X-ray fluorescence (XRF) microscopy reveals structural and chemical properties simultaneously. While ptychography can achieve diffraction-limited spatial resolution, the resolution of XRF is limited by the X-ray probe size. Here, we develop a machine learning (ML) model to overcome this problem by decoupling the impact of the X-ray probe from the XRF signal. The enhanced spatial resolution was observed for both simulated and experimental XRF data, showing superior performance over the state-of-the-art scanning XRF method with different nano-sized X-ray probes. Enhanced spatial resolutions were also observed for the accompanying XRF tomography reconstructions. Using this probe profile deconvolution with the proposed ML solution to enhance the spatial resolution of XRF microscopy will be broadly applicable across both functional materials and biological imaging with XRF and other related application areas.

Evaluation of Portable X-ray Fluorescence Analysis and Its Applicability As a Tool in Geochemical Exploration

Large-scale, high-density geochemical explorations entail enormous workloads and high costs for sample analysis, but, for early mineral exploration, absolute concentrations are not essential. Geochemists require ranges, dynamics of variation, and correlations for early explorations rather than absolute accuracy. Thus, higher work efficiency and lower costs for sample analysis are desirable for geochemical exploration. This study comprehensively analyzed the reliability and applicability of portable X-ray fluorescence (pXRF) spectrometry in geochemical exploration. The results show that pXRF can be applied effectively to rock and rock powder samples, and sample preparation and a longer detection time have been shown to increase the precision of the pXRF results. When pXRF is used on rock samples, if less than 30% of the samples are assessed as containing an element, the element is usually undetectable using pXRF when these rock samples are prepared as rock powders, indicating that the data about the detected element are unreliable; thus, it is suggested that some representative samples should be selected for testing before starting to use a pXRF in a geochemical exploration project. In addition, although the extended detection time increased the reliability of the analysis results, an increase in detection time of more than 80 s did not significantly affect the accuracy of the results. For this reason, the recommended detection time for the pXRF analysis of rock powder samples is 80 s for this study. pXRF has the advantages of being low-cost, highly efficient, and stable, and its results are reliable enough to exhibit the spatial distribution of indicator elements (arsenic, nickel, lead, sulfur, titanium, and zinc) in polymetallic mineralization exploration. Therefore, pXRF is recommendable for practical use in geochemical exploration.

Using X‐ray fluorescence to examine ancient Maya granite ground stone in Belize

AbstractWhile ubiquitous among ancient Maya sites in Mesoamerica, archaeological analysts frequently overlook the interpretive potential of ground stone tools. The ancient Maya often made these heavy, bulky tools of coarse‐grained, heterogeneous materials that are difficult to chemically source, unlike obsidian. This paper describes an application of handheld, energy‐dispersive X‐ray fluorescence (XRF) to provenance ground stone artifacts (tools and architectural blocks) composed of granite: a nonhomogenous, phaneritic stone. We present a multicomponent methodology that independently tested whole‐rock, thin‐sectioned, and powdered samples by petrographic microscope, conventional, lab‐based XRF, and portable XRF units, which yielded comparable results. After establishing distinct geochemical signatures for the three geographically restricted granite plutons in Belize, we devised a field‐based XRF application on a whole rock that could replicate the compositional readings of lab‐based XRF on powdered materials with sufficient accuracy and reliability. We applied this multishot XRF technique to granite ground stone items from a range of ancient Maya sites throughout Belize; we discuss two specific case studies herein. Our results underscore the widespread potential of multishot XRF applications for determining the provenance of coarse‐grained, heterogeneous rock materials. These results can help push the boundaries from one‐dimensional, functional explanations of ground stone items to their social and ideological dimensions, alongside deeper understandings of granite resource management.

Application of a handheld X-ray fluorescence analyzer for the quantification of air particulate matter on Teflon filters

Elemental characterization of air particulate matter samples through the application of X-ray fluorescence (XRF) spectrometry is a widespread analytical technique. This work presents the optimization and calibration methodology of a handheld XRF spectrometer and its subsequent application in elemental quantification of unknown particulate matter samples. The optimization of the handheld spectrometer was conducted through investigation of the elemental sensitivities and Limits of Detection (LoD) at variable excitation conditions (voltage, filter). Accordingly, five optimum operating conditions were obtained each one targeted in different elemental range: 1) Z = 11–12, 2) 12 < Z < 17, 3) 16 < Z < 23, 4) 22 < Z < 31 and 5) 30 < Z < 92. Subsequently, a number of reference (5 multi-element and 42 compound/single-element) materials were used to obtain calibration curves for 24 elements (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Pb). Weighted least-square regression analysis was implemented to best fit the experimentally measured intensities with mass loadings resulting for most of the elements to high correlations (Pearson r > 0.98) and low statistical error. In addition, intercomparison of the elemental concentrations from 28 unknown particulate matter samples between the handheld and a benchtop XRF spectrometer showed good agreement.

Partial least squares assisted influence coefficients concept improves accuracy in X-ray fluorescence analysis

Routine application of X-ray fluorescence (XRF) spectrometry in laboratory practice requires special procedures to correct for matrix effects. One of the most popular procedures is the influence coefficients method. In this method the regression equation relating analytical signal to the target element concentration is extended with empirical terms correcting the influence from particular matrix elements. While the influence coefficients method is quite accurate, it is rather laborious as it requires individual selection of matrix terms for each element under study. The influence coefficients method is based on the least squares regression technique, thus the number of matrix correction terms is limited by the number of available standard calibration samples. Here we propose a very simple technique that can take into account an unlimited number of terms in the influence coefficients method through the employment of partial least squares regression (PLS) where spectral intensities, their ratios and squared intensities are employed as variables. Unlike traditional application of PLS in XRF studies where the regression model is built using spectral intensities only, the proposed approach inspired by classic influence coefficients allows elimination of complex specific XRF matrix effects. The paper describes the suggested method and demonstrates its' performance in two EDXRF data sets with significant matrix effects (ore and steel samples).

Recent Achievements in NAA, PAA, XRF, IBA and AMS Applications for Cultural Heritage Investigations at Nuclear Physics Institute, Řež

Five case studies are reported on the use of neutron and photon activation analysis (NAA and PAA, respectively), X-ray fluorescence (XRF) analysis, ion beam analysis (IBA), and accelerator mass spectrometry (AMS) for the elemental characterization or dating of various objects of cultural heritage, such as building materials, pottery, metallic artefacts, ancient decorations, or the remains of historical personalities. The use of the individual techniques or their combination proved a useful, frequently indispensable tool for revealing the provenance of the artefacts, the method and time of their manufacturing, the elucidation of ancient human activities, or the verification of various hypotheses or legends related to the artefacts.

X-ray Fluorescence Spectroscopy of Picrolite Raw Material on Cyprus

Picrolite artefacts comprise some of the most distinctive material remains in the prehistory of the island of Cyprus, in the Eastern Mediterranean. Picrolite exploitation dates from at least 12,000 years ago for the manufacture of personal ornaments and items with a symbolic function. It is commonly assumed that picrolite nodules were collected in secondary deposits on an ad hoc basis. This narrative, however, ignores the fact that picrolite carriers can only be found in very specific locations on the island, discrete from each other. Here we report initial outcomes of the application of handheld portable X-ray fluorescence (HHpXRF) and synchrotron-based X-ray fluorescence spectroscopy (SR-μXRF) to the analysis of picrolite raw materials performed at the newly opened PUMA beamline of the SOLEIL Synchrotron Radiation Facility. Our work refines the basic characteristics of the elemental constituents of the picrolite raw material and highlights key micro-structural differences between two distinct source regions on the Troodos Massif in western Cyprus. Picrolite source characterisation is expected to contribute significant new knowledge to the study of rare raw material consumption, prehistoric social organisation, networking and possible long-distance exchange of this idiosyncratic raw material within and beyond the island’s geographic boundaries.

Book review for a book by M. Haschke, J. Flock, M. Haller “Laboratory Applications of X-ray Fluorescence”, Wiley. 2021, 464 pp., 263 illustrations.

The use of X-ray fluorescence analysis (XRF) has been constantly expanding in recent years. The number of users without special training is increasing. This paper provides information on the monograph by M. Haschke, J. Flock, and M. Haller “Laboratory Applications of X-ray Fluorescence”. The book was published by Wiley-VCH. The book under review was written by experts with extensive experience in XRF. The authors made a significant contribution to the development of X-ray fluorescence analysis. The book consists of a Preface, a List of abbreviations and symbols, Information about authors, an Introduction, 18 Chapters, two Appendixs (A - Tables, B - Important information), a References and an Index. The material of the book in the review is discussed chapter by chapter. The book presents various sample preparation procedures that are typical for XRF and discusses their impact on the precision and accuracy of the analysis. The main types of X-ray spectrometers, as well as the design, construction and features of the operation of individual components of the devices are considered. The main techniques for measuring and evaluating X-ray spectra are discussed, and the metrological characteristics of XRF are compared with other analytical methods. In full accordance with the title of the book, the authors paid the main attention to the discussion of options for solving various analytical problems using XRF. Homogeneous and heterogeneous, solid and liquid materials, application in geology, ecology, biology, industrial enterprises, research laboratories in the study of objects of heritage are considered. It should be noted the presence in the book of the Appendix “Important information”. Prepared by the authors, a modern high quality reference guide will be useful for both beginners and qualified professionals. A clear presentation of the material allows us to recommend it as a teaching aid for students and undergraduates. It seems that the book will be in demand in the laboratories of research institutes and universities, as well as in the laboratories of industrial enterprises.

Okra (Abelmoschus esculentus) in a refugee context in East Africa: Kitchen gardening helps with mineral provision

Kitchen gardening is considered a way to reconnect with agriculture and complement the cereal-based relief food offered to refugees in East Africa. This work aimed at profiling mineral content of okra in four refugee camps and settlements located in Ethiopia and Uganda and its contribution to adequate intake (AIs) or recommended dietary allowances (RDAs) for young children and pregnant and lactating women (PLW). The study also evaluated the applicability of portable X-ray fluorescence (PXRF) as compared with inductively coupled plasma mass spectrometry (ICP-MS) for mineral profiling of okra powder samples. The contents of minerals (mg kg−1) from the ICP-MS readings were in the following ranges: K (14,385–33,294), Ca (2610–14,090), P (3178–13,248), Mg (3896–7986), Cu (3.81–19.3), Fe (75.7–1243), Zn (33–141) and Mn (23.1–261). Regardless of geographic origin, at low-end consumption probability (17 g day−1 for young children and 68 g day−1 for PLW), okra could contribute ˂ 15% (2.7–12.9%) AI for macro-minerals (K and Ca). In addition, the contributions to RDA values for Fe and Zn, elements of known public health interest, ranged from 4.5 to 34.7% for young children. Interestingly, regression lines revealed strong agreement between ICP-MS and PXRF readings for Mn and Zn, with R2 values > 0.91. This information is useful in support of nutrition-sensitive kitchen gardening programs through scaling culturally important crops in refugee settings.

Comparing three sample preparation techniques for portable X-ray fluorescence: A case study of Coarse Orange ceramic jars, Veracruz, Mexico

Applications of energy dispersive portable X-ray fluorescence (pXRF; Olympus Vanta M Series VMR) for the chemical analysis of ceramic fabrics are gaining importance for archaeology. In addition to the broad accessibility of the instruments and their ability to gain first-look chemical data without destroying archaeological samples, the ability to bring the instrument to the field may be the only option for researchers working internationally. Through a systematic evaluation of quality control measures applied to multiple standard and in-house reference materials, we conclude that the pXRF employed in this study can precisely and accurately quantify many elements, some of which are not reported or possess high detection limits as measured by other instruments, including neutron activation analysis (NAA). We also demonstrate that analyzing ceramics in different states – intact sherds, homogenized powders, or pressed planchets – produce internally consistent results within categories but yield different results across sample preparation techniques. Finally, we re-analyze an archaeological sample of Coarse Orange jars from the Classic period Tuxtla Mountains, Veracruz, Mexico previously studied through petrography and NAA (Stoner, 2013; Stoner et al., 2008). Analyses of samples processed into homogenized powders yield the most accurate and precise results, rivaling the analytical capabilities of NAA for characterizing this particular sample of ceramics. Analysis of intact sherds and pressed planchets yields sufficient results to reproduce the main compositional groups identified through prior NAA, but loses some detail necessary to separate subgroups.

Portable X-ray Fluorescence as a Rapid Determination Tool to Detect Parts per Million Levels of Ni, Zn, As, Se, and Pb in Human Toenails: A South India Case Study.

Chronic exposure to inorganic pollutants adversely affects human health. Inductively coupled plasma mass spectrometry (ICP-MS) is the most common method used for trace metal(loid) analysis of human biomarkers. However, it leads to sample destruction, generation of secondary waste, and significant recurring costs. Portable X-ray fluorescence (XRF) instruments can rapidly and nondestructively determine low concentrations of metal(loid)s. In this work, we evaluated the applicability of portable XRF as a rapid method for analyzing trace metal(loid)s in toenail samples from three populations (n = 97) near the city of Chennai, India. A Passing-Bablok regression analysis of results from both methods revealed that there was no proportional bias among the two methods for nickel (measurement range ∼25 to 420 mg/kg), zinc (10 to 890 mg/kg), and lead (0.29 to 4.47 mg/kg). There was a small absolute bias between the two methods. There was a strong proportional bias (slope = 0.253, 95% CI: 0.027, 0.614) between the two methods for arsenic (below detection to 3.8 mg/kg) and for selenium when the concentrations were lower than 2 mg/kg. Limits of agreement between the two methods using Bland-Altman analysis were derived for nickel, zinc, and lead. Overall, a suitably calibrated and evaluated portable XRF shows promise in making high-throughput assessments at population scales.

In vivo Quantification of Bone Lead and Strontium using Portable X-ray Fluorescence (XRF)

BACKGROUND AND AIM: Exposure to lead (Pb) or strontium (Sr) is of concern due to potential neurotoxicity or impaired bone health, respectively. Human bone is reliable biomarker for cumulative Pb and Sr exposures and for studying associated health outcomes. However, the applicability of standard K-shell x-ray fluorescence (KXRF) bone Pb measurement technology is significantly limited by its lack of portability, long measurement times, and licensing - restricting its use in large-scale population studies. In this study, we measured Pb and Sr in two populations using portable x-ray fluorescence (XRF), compare bone Pb measurements from a portable XRF device and a KXRF device, and assess differences in bone Sr level across sex, age and ethnicity. METHODS: We measured bone Pb and Sr concentrations in mid-tibia bone using portable XRF in 76 Americans, age 38 – 95 years, living in Indiana, and bone Sr concentrations in 29 Chinese, age 53 – 82 years, living in Shanghai. RESULTS:The detection limits for 3-minute portable XRF measurements for in vivo bone Pb and Sr ranged from 4.0 to 12.6 ug/g dry bone (ppm) and 2.0 to 5.2 ppm, respectively, with overlying soft tissue (ST) thickness ranging from 2 to 6 mm. Bone Pb measurements via KXRF and portable XRF were highly correlated: R = 0.73 (95% CI, 0.28 to 0.70) among participants with ST thickness 6 mm (72% of the measured population). Furthermore, the mean bone Sr concentration for American participants was 66.1 ppm (95%CI: 56.5 ppm, 75.6 ppm) and for Chinese was 74.7 ppm (95%CI: 55.6 ppm, 93.8 ppm). Interestingly, the bone Sr in Chinese female participants decreased with age, while the bone Sr in American female participants increased with age. CONCLUSIONS:We conclude that portable XRF is a valuable technology to study health outcomes related to Pb and Sr exposures. KEYWORDS: Heavy Metals, Exposure Assessment, X-ray Fluorescence, Lead (Pb), Strontium (Sr)