Portable X-ray Fluorescence System Research Articles

Investigation of the accuracy of a portable 109Cd XRF system for the measurement of iron in skin

We have previously reported the design of a portable 109Cd x-ray fluorescence (XRF) system to measure iron levels in the skin of patients with either iron overload disease, such as thalassemia, or iron deficiency disease, such as anemia. In phantom studies, the system was found to have a detection limit of 1.35 μg Fe per g of tissue for a dose of 1.1 mSv. However, the system must provide accurate as well as precise measurements of iron levels in the skin in order to be suitable for human studies. The accuracy of the system has been explored using several methods. First, the iron concentrations of ten pigskin samples were assessed using both the portable XRF system and ICP-MS, and the results were compared. Overall, it was found that XRF and ICP-MS reported average values for iron in skin that were comparable to within uncertainties. The mean difference between the two methodologies was not significant, 2.5 ± 4.6 μg Fe per g. On this basis, the system could be considered accurate. However, ICP-MS measurements reported a wider range of values than XRF, with two individual samples having ICP-MS results that were significantly elevated (p < 0.05) compared to XRF. Synchrotron μXRF maps of iron levels in pigskin were acquired on the BioXAS beam line of the Canadian Light Source. The μXRF maps indicated two important features in the distribution of iron in pigskin. First, there were small areas of high iron concentration in the pigskin samples, that were predominantly located in the dermis and hypodermis at depths greater than 0.5 mm. Monte Carlo modelling using the EGS 5 code determined that if these iron ‘hot spots’ were located towards the back of the skin at depths greater than 0.5 mm, they would not be observed by XRF, but would be measured by ICP-MS. These results support a hypothesis that iron levels in the two samples that reported significantly elevated ICP-MS results compared to XRF may have had small blood vessels at the back of the skin. Second, the synchrotron μXRF maps also showed a narrow (approximately 100μm thick) layer of elevated iron at the surface of the skin. Monte Carlo models determined that, as expected, the XRF system was most sensitive to these skin layers. However, the simulations found that the XRF system, when calibrated against homogenous water-based phantoms, was found to accurately measure average iron levels in the skin of normal pigs despite the greater sensitivity to the surface layer. The Monte Carlo results further indicated that with highly elevated skin surface iron levels, the XRF system would not provide a good estimate of average skin iron levels. The XRF estimate could, with correction factors, provide a good estimate of the iron levels in the surface layers of skin. There is limited data on iron distribution in skin, especially under conditions of disease. If iron levels are elevated at the skin surface by diseases including thalassemia and hemochromatosis, this XRF device may prove to be an accurate clinical tool. However, further data are required on skin iron distributions in healthy and iron overload disease before this system can be verified to provide accurate measurements.

Assessment of X-ray fluorescence capabilities for nail and hair matrices through zinc measurement in keratin reference materials

BackgroundNovel and emerging biomarkers of zinc status are being developed to help study and address zinc deficiency around the world. Two potential biomarkers, nail and hair, involve the measurement of zinc from easily accessible keratin-based components of the body. Portable X-ray fluorescence (XRF) is a relatively new approach to the assessment of zinc in nail or hair, and has a number of compelling advantages compared with other techniques. The aim of the current study was to test the ability of XRF to measure zinc in keratinized reference materials (RMs) designed to simulate nail and hair. MethodsFour Keratin Matrix RMs were prepared and characterized for numerous trace elements by the New York State Department of Health’s Wadsworth Center. The Keratin Matrix RMs consisted of powdered samples of caprine (goat) horns pooled from several animals. Concentrations of zinc, as assessed by inductively coupled plasma mass spectrometry (ICP-MS), were similar to what would be expected from human nail or hair tissues. Repeat measurements of the RMs were made using a portable XRF system. The XRF zinc results were compared with the ICP-MS zinc concentrations. Three different approaches to quantifying the zinc content by XRF were performed: (1) zinc signal to total signal ratio, (2) zinc signal to sulfur signal ratio, and (3) system output zinc concentration. ResultsThe portable XRF results from a given RM were found to be consistent across repeat trials under all three approaches to XRF quantitation. Precision, calculated as the relative standard deviation of repeat measurements ranged from an average result of 0.8 % (using the system output zinc concentration method) to 6.1 % (using the zinc signal to sulfur signal ratio method). Measurement of the RMs provided XRF zinc results which scaled well with ICP-MS zinc concentration, particularly when using the XRF zinc to total and system zinc concentration methods. A Bland-Altman plot showed that the XRF system zinc concentration output exceeded the ICP-MS zinc concentration by, on average, 10.2 % ± 1.2 %. ConclusionOverall, both accuracy and precision of measurement were found to be promising for portable XRF, provided appropriate conversions to concentration are introduced. The results of this study indicate that portable XRF is an effective and dependable method of assessing zinc concentration in keratinized tissue RMs. This will have implications for the future use of portable XRF to monitor zinc status in humans through measurements of nail and hair.

Analysis of a wooden statue by non‐destructive X‐ray techniques

AbstractIn this study, the characterization of the “Santa Luzia” statue was carried out through three non‐destructive X‐ray techniques: X‐ray Fluorescence (XRF), Digital Radiography (DR), and Computed Tomography (CT). The wooden statue dates from the 18th century. It was carved in Portugal and is currently located at the Santa Luzia church—one of the oldest churches built in Rio de Janeiro. The portable XRF system used in this study is composed of an Ag target X‐ray tube and an silicon drift detector detector with energy resolution of 122 eV at 5.9 keV. Several spectra were obtained in different regions of the statue. For the DR and CT evaluations, a portable 120 kV X‐ray tube and a 410 × 410 mm a‐Si flat panel detector with a pixel size of 200 μm were used. Individual radiographs of the parts of the statue were acquired and merged into a single image, in order to show its complete radiography. Finally, the CT images of the head of the statue were taken in angular steps of 2 degrees and, after the reconstruction process, the data were analyzed by means of appropriate software. The elements found in the XRF analysis suggest the presence of the pigments lead white, red lead, zinc white, titanium white, vermilion and emerald green. All of them are in accordance with the pigments used by the artists during the statue's historical period. The 3 exceptions were the zinc white and titanium white pigments, which may be an evidence of modern interventions, and the emerald green pigment, which appears to be a repainting of the green region. The radiographic images showed the manufacturing process of the statue, as well as its structural condition. The assembling of wooden blocks, the presence and type of nails and spikes, and regions of different densities were found in the analysis. In the statue's head, the joining of the face with the main part of the statue is clearly visible, and also the hollow glass eye. The CT analysis was able to better detail this section as a spherical cavity in the central part of the head, as well as the presence of a high‐density fragment inside the hole for the fixation of the aureole. The type of glass eye was identified as blown‐glass eye, which is commonly used in devotional statues.

Investigating methods of normalization for X-ray fluorescence measurements of zinc in nail clippings using the TOPAS Monte Carlo code

Development of portable X-ray fluorescence devices has made it easier to quickly assess trace elements such as zinc in human tissue. A TOPAS Monte Carlo code was used to investigate the use of a portable X-ray fluorescence system for detecting zinc in nail clippings. The obtained energy spectra from different nail thicknesses were analyzed and three different normalization techniques (coherent, Compton, and entire spectrum) were introduced. The simulation results suggested that coherent normalization can be a particularly robust normalization procedure.

Analysis of painting Victor Meirelles’ “Passagem de Humaitá” by XRF

Analysis of historical artifacts, it's a multidisciplinary field of research known as archaeometry, has expanded greatly in recent years. One of the reasons for this expansion was the great effort of physicists and engineers, who focused on the development of portable instruments, that allow analyses in situ and non-destructive of these artifacts. The X-Ray Fluorescence (XRF) is techniques of the most used in this field of study. In this work the XRF was used to analysis the artwork "Passagem de Humaitá", by the Brazilian painter Victor Meirelles, dated 1872. The painting, which has dimensions of 268 cm x 405 cm, is exposed at National Historical Museum located in Rio de Janeiro. The analyses were carried out in situ with portable XRF system model TRACER IV from Bruker, which has Rh anode and can operate with maximum voltage and current of 40 kV and 200 μA. Spectra of more than 80 points of the painting were obtained, with the tube operating at voltage of 40 kV and a current of 10 μA, and the spectra were collected during 60 seconds. The results allowed to conclude that the painter used pigments such as vermilion and/or cinnabar [HgS], calcite [CaCO3], zinc white [ZnO], lead white [(PbCO3)2·Pb(OH)2], red ocher [Fe2O3], brown umbra [Fe2O3.MnO2].

Assessing arsenic in human toenail clippings using portable X-ray fluorescence

Arsenic is a toxic metalloid which has been associated with a wide range of health effects in humans including skin abnormalities and an elevated risk of skin, bladder, kidney, and lung cancer, diabetes, and cardiovascular disease. The measurement of arsenic concentration in nail clippings is often used in population studies as an indicator of arsenic exposure. Portable X-ray fluorescence (XRF) is an emerging technique for measuring arsenic in nail clippings. In the current study, single toenail clippings from 60 Atlantic Canadian participants were assessed for arsenic using a new portable XRF approach. A mono-energetic portable XRF system using doubly curved crystal optics was used to measure each clipping for a total of 900 s. Energy spectra from each clipping were analyzed for arsenic characteristic X-rays to provide a normalized arsenic signal. The same clippings were then analyzed for arsenic concentration using a “gold standard” method of inductively coupled plasma mass spectrometry (ICP-MS). Nail clipping arsenic concentrations measured by ICP-MS ranged from 0.030 μg/g to 2.57 μg/g, with a median result of 0.14 μg/g. Portable XRF results for arsenic were compared against ICP-MS arsenic concentrations, with a linear equation of best fit determined between the two variables. A correlation coefficient of r = 0.77 was found from the 59 nail clippings returning an ICP-MS arsenic concentration above the limit of quantitation. When the comparison was limited to the 20 clippings having an XRF normalized signal at least twice as large as the associated uncertainty of measurement, the correlation coefficient was r = 0.89. With the selection of an arsenic concentration of 0.1 μg/g as a cut-off value between “exposed” and “non-exposed” individuals, the XRF method provided a test sensitivity of 76% and a specificity of 81%. The corresponding positive predictive value was 88% and the negative predictive value was 65%. The portable XRF technique used in this study shows promise as a means of assessing arsenic concentration in toenail clippings.

Portable X-ray fluorescence of zinc applied to human toenail clippings

Zinc is an essential trace element in humans. Zinc deficiency can result in a range of serious medical conditions which include effects on growth and development, the immune system, the central nervous system, and the gastrointestinal system. Diagnosis of zinc deficiency is often precluded by the lack of a noninvasive and reliable biomarker. Zinc concentration in nail is considered an emerging biomarker of zinc status in humans. Whether zinc in nail accurately reflects zinc status is beyond the scope of the current study, but is an important research question. The development of a portable method to quickly assess zinc concentration from a single nail clipping could be a useful advance. In this study, single toenail clippings from 60 individuals living in Atlantic Canada were measured for zinc using a portable X-ray fluorescence (XRF) technique. These samples were obtained from the Atlantic PATH cohort, part of the largest chronic disease study ever performed in Canada. Each toenail clipping was measured using three 300 s trials with a mono-energetic portable XRF system. Results were then assessed using two different approaches to the XRF analysis: (1) factory-calibrated zinc concentrations were output from each trial, and (2) energy spectra were analyzed for the characteristic X-rays resulting from zinc. Following the measurement of zinc using the non-destructive portable XRF method, the same clippings were measured for zinc concentration using the “gold standard” technique of inductively coupled plasma-mass spectrometry (ICP-MS). A linear equation of best fit was determined for the relationship between average XRF output zinc concentration and ICP-MS zinc concentration, with a correlation coefficient r = 0.60. Similarly, a linear equation of best fit was found for the relationship between a normalized XRF energy spectrum zinc signal and ICP-MS zinc concentration, with a correlation coefficient r = 0.68. Individual ICP-MS zinc concentrations ranged from 32 μg/g to 140 μg/g, with a population average of 85 μg/g. The results of this study indicate that portable XRF is a sensitive method for the measurement of zinc in a single nail clipping, and provides a reasonable estimation of zinc concentration. Further method development is required before portable XRF be considered a routine alternative to ICP-MS for the assessment of zinc in nail clippings.

Assessment of alternative methods for analyzing X-ray fluorescence spectra

When analyzing characteristic peaks in X-ray fluorescence (XRF) spectra, the peak area is the value most often used to quantify peak size. However, some studies have reported the amplitude of the peak instead of the area. When the width of the peak is allowed to vary from trial to trial in order to provide the best possible fit to the data, these two alternative methods can yield slightly different results. In the current study, these two approaches to peak analysis are compared for data obtained from bone reference materials having certified lead concentrations of 1.09 ± 0.03 μg/g, 16.1 ± 0.3 μg/g, 13.2 ± 0.3 μg/g, and 31.5 ± 0.7 μg/g. Measurements were made with an Olympus Innov-X Delta Premium portable XRF system. Using both the area and amplitude methods, lines of best fit were constructed for the lead Lα and lead Lβ signals as a function of lead concentration. Additionally, coefficients of variation were calculated for each reference material and condition of analysis. To assess possible variations over time, the procedure was performed at two points separated by about one year. The amplitude and area methods were found to produce results which were consistent and proportional. Using either method, lead XRF signal plotted as a function of known lead concentration produced adjusted r2 values of ∼0.99. The amplitude method provided slightly higher adjusted r2 values overall. Coefficients of variation were generally very similar between the two methods, although more pronounced differences emerged from measurements of the lowest concentration reference material.

Investigations of minor elements in early aluminium artefacts

Study of the minor and trace element contents in the composition of early aluminium is interesting from a cultural history perspective because it can provide information on the evolution of aluminium smelting practice. A range of aluminium artefacts from the Swiss National Museum and the Lausanne Historical Museum, Switzerland, have been characterised with regard to their minor and trace element composition. This was performed using external beam Particle Induced X-ray Emission (PIXE) with 1 MeV protons and a portable X-ray fluorescence system. The concentration of Mn and Pb was significantly higher for artefacts produced by the amalgam process which confirms studies reported by others.

Portable X-ray fluorescence system to measure Th and U concentrations

This study reports the results obtained in the analysis of waste material samples generated by the industries of phosphate fertilizers, in particular, the use of specific filters in a portable X-ray fluorescence system, a simple equipment allowing the characterization, identification and quantification of low concentrations of Th and U (ppm). The industrial byproduct is classified as a Technologically-Enhanced, Naturally-Occurring Radioactive Material - TENORM, and therefore requires monitoring for its radio-toxic activity due to the presence of radioactive thorium and uranium families. From the results obtained, it is concluded that this technique is able to determine the contents of these elements to concentrations of tens of ppm in measurements of about 300 s, and a small sample amount (∼0.1 g).

Feasibility of a portable X-ray fluorescence device for bone lead measurements of condor bones

Lead based ammunition is a primary source of lead exposure, especially for scavenging wildlife. Lead poisoning remains the leading cause of diagnosed death for the critically endangered California condors, which are annually monitored via blood tests for lead exposure. The results of these tests are helpful in determining recent exposure in condors and in defining the potential for exposure to other species including humans. Since condors are victim to acute and chronic lead exposure, being able to measure both would lend valuable information on the rates of exposure and accumulation through time. A commercial portable X-ray fluorescence (XRF) device has been optimized to measure bone lead in vivo in humans, but this device could also be valuable for field measurements of bone lead in avian species. In this study, we performed measurements of bone Pb in excised, bare condor bones using inductively coupled plasma mass spectrometry (ICP-MS), a cadmium 109 (Cd-109) K-shell X-ray fluorescence (KXRF) system, and a portable XRF system. Both KXRF and portable XRF bone Pb measurement techniques demonstrated good correlations with ICP-MS results (r=0.93 and r=0.92 respectively), even with increasing skin thickness (r=0.86 between ICP-MS and portable XRF at 1.54mm of soft tissue). In conclusion, our results suggest that a portable XRF could be a useful option for measurement of bone Pb in avian species in the field.

Detection of lead in bone phantoms and arsenic in soft tissue phantoms using synchrotron radiation and a portable x-ray fluorescence system

The differences and commonalities between x-ray fluorescence results obtained using synchrotron radiation and a portable x-ray fluorescence device were examined using arsenic in soft tissue phantoms and lead in bone phantoms. A monochromatic beam energy of 15.8 keV was used with the synchrotron, while the portable device employed a rhodium anode x-ray tube operated at 40 kV. Bone phantoms, dosed with varying quantities of lead, were made of Plaster of Paris and placed underneath skin phantoms of either 3.1 mm or 3.9 mm thickness. These skin phantoms were constructed from polyester resin, and dosed with varying amounts of arsenic. Using an irradiation time of 120 s, arsenic Kα and Kβ, and lead Lα and Lβ characteristic x-ray peaks were analysed. This information was used to calculate calibration line slopes and minimum detection limits for each data set. As expected, minimum detection limits were much lower at the synchrotron for detecting arsenic and lead. Both approaches produced lower detection limits for arsenic in soft tissue than for lead in bone when simultaneous detection was attempted. Although arsenic Kα and lead Lα emissions share similar energies, it was possible to detect both elements in isolation by using the arsenic Kβ and lead Lβ characteristic x-rays. Greater thickness of soft tissue phantom reduced the ability to detect the underlying lead. Experiments with synchrotron radiation could help guide future efforts toward optimizing a portable x-ray fluorescence in vivo measurement device.

Feasibility of measuring arsenic and selenium in human skin using in vivo x-ray fluorescence (XRF)—a comparison of methods

In recent years, in vivo measurement systems of arsenic in skin by K-shell x-ray fluorescence (XRF) have been developed, including one which was applied in a pilot study of human subjects. Improved tube-based approaches suggest the method can be further exploited for in vivo studies. Recently, it has been suggested that selenium deficiency is correlated with arsenic toxicity. A non-invasive measurement of both elements could therefore be of potential interest. The main aim of this current study was to evaluate and compare the performance of an upgraded portable XRF system and an advanced version of the benchtop XRF system for both selenium and arsenic. This evaluation was performed in terms of arsenic and selenium Kα detection limits for a 4W gold anode Olympus InnovX Delta portable analyzer (40 kVp) in polyester resin skin-mimicking phantoms. Unlike the polychromatic source earlier reported in the literature, the benchtop tube-based technique involves monochromatic excitation (25 W silver anode, manufactured by x-ray optics, XOS) and a higher throughput detector type. Use of a single exciting energy allows for a lower in vivo dose delivered and superior signal-noise ratio. For the portable XRF method, arsenic and selenium minimum detection limits (MDLs) of 0.59 ± 0.03 ppm and 0.75 ± 0.02 ppm respectively were found for 1 min measurement times. The MDLs for arsenic and selenium using the benchtop system were found to be 0.35 ± 0.01 ppm and 0.670 ± 0.004 ppm respectively for 30 min measurement times. In terms of a figure of merit (FOM), allowing for dose as well as MDL, the benchtop system was found to be superior for arsenic and the two systems were equivalent, within error, for selenium. We shall discuss the performance and possible improvements of each system, their ease of use and potential for field application.

In vivo quantification of lead in bone with a portable x-ray fluorescence system—methodology and feasibility

This study was conducted to investigate the methodology and feasibility of developing a portable x-ray fluorescence (XRF) technology to quantify lead (Pb) in bone in vivo. A portable XRF device was set up and optimal settings of voltage, current, and filter combination for bone lead quantification were selected to achieve the lowest detection limit. The minimum radiation dose delivered to the subject was calculated by Monte Carlo simulations. An ultrasound device was used to measure soft tissue thickness to account for signal attenuation, and an alternative method to obtain soft tissue thickness from the XRF spectrum was developed and shown to be equivalent to the ultrasound measurements (intraclass correlation coefficient, ICC = 0.82). We tested the correlation of in vivo bone lead concentrations between the standard KXRF technology and the portable XRF technology. There was a significant correlation between the bone lead concentrations obtained from the standard KXRF technology and those obtained from the portable XRF technology (ICC = 0.65). The detection limit for the portable XRF device was about 8.4 ppm with 2 mm soft tissue thickness. The entrance skin dose delivered to the human subject was about 13 mSv and the total body effective dose was about 1.5 µSv and should pose minimal radiation risk. In conclusion, portable XRF technology can be used for in vivo bone lead measurement with sensitivity comparable to the KXRF technology and good correlation with KXRF measurements.

SANDRA: a portable XRF system for the study of Mexican cultural heritage

This work presents the portable X-ray system SANDRA (Sistema de Analisis No Destructivo por RAyos X or System for Non Destructive Analysis using X-rays) developed at the Physics Institute of the UNAM, Mexico, for the study of Mexican cultural heritage collections. The X-ray fluorescence (XRF) SANDRA device can use 75 W Mo, Rh and W X-ray tubes and Amptek Si-PIN and Cd-Te detectors that are selected and combined depending on the elemental range detection requirements and the specific problem to be studied. In this paper, a full description and characterization of this system, sensitivities for the X-ray tubes and detectors as well as the detection limits are discussed. Examples of applications to technological studies on pre-Columbian metallic artifacts and analysis of color materials of ancient Mexican codex are shown. Copyright © 2010 John Wiley & Sons, Ltd.

Precious metals determination in ancient coins by portable ED-XRF spectroscopy with a 238Pu source

A portable X-ray fluorescence system (pXRF) was employed to analyse a set of gold, silver and billon coins from the collection of the Museu Histórico Nacional do Rio de Janeiro (MHN), struck during the Brasil Colônia period, under the Dutch occupation, and in Portuguese mints under the reigns of Fernando I (1367 to 1383) and his successor João I (1383 to 1433). The experimental setup consisted of a mini Si-PIN detector and a radioactive source of 238Pu for the excitation of the samples. The aim of the study was to test the possibilities and limitations of this portable system for the determination of the coins’ base alloys, and to verify whether the results obtained were consistent with historical facts. The Brasil Colônia period coins show about 80.5% gold and 96.8% silver. For the Portuguese coins, we could identify a possible monetary debasement during the reign of João I. No matrix corrections were made for these preliminary results.

Uso da fluorescência de raios X portátil (XRF) in vivo como técnica alternativa para acompanhamento dos níveis de ferro em pacientes com sobrecarga de ferro

Foi investigada a viabilidade da aplicação da técnica de fluorescência de raios X (XRF) como alternativa para acompanhamento dos níveis de ferro em pacientes portadores de talassemia maior (beta-thalassemia) e hemocromatose hereditária (HH). As medidas foram realizadas no Hemocentro do Hospital Universitário e no Laboratório de Física Nuclear Aplicada da Universidade Estadual de Londrina. Foi acompanhada uma portadora de talassemia maior e quatro pessoas sadias. Foi utilizado um sistema portátil de XRF constituído de uma fonte de Raios X de 238Pu e um detector de SiPIN diodo, para as medidas in vivo na mão. O sistema foi calibrado medindo simulados de solução aquosa com 15 a 150 ppm de ferro. A duração de cada medida foi de 50 s. O limite de detecção (LLD) atingido foi de 13 ppm de ferro. A dose de radiação na pele foi de 10 mSv. A paciente de talassemia apresentou 74 ± 6 ppm de ferro, enquanto pessoas sadias apresentaram valor médio de 53 ± 5 ppm de ferro. Os resultados estão de acordo com a literatura, que informa níveis de ferro na pele de 15 a 60 ppm em pessoas sadias e de 70 a 150 ppm em pacientes portadores da talassemia maior. Foi concluído ser viável a aplicação da XRF para acompanhamento de pacientes de talassemia maior e HH.

Factorial design for Fe, Cu, Zn, Se and Pb preconcentration optimization with APDC and analysis with a portable X-ray fluorescence system

Preconcentration of heavy metals in water with ammonium pyrrolydine dithiocarbamate (APDC) is a common practice in analytical chemistry. A literature review on this topic showed that several authors use this precipitation agent, but in different preconcentration conditions, conducting to divergent results. The objective of this work is to use factorial design to optimize the factors involved in the preconcentration process of heavy metals using APDC. Five factors were studied: sample volume, solution pH, APDC concentration, APDC volume and stirring time. The assays were performed by energy dispersive X-ray fluorescence (EDXRF). The values for detection limits within 95% confidence level, in μg L −1, were: Fe (6.0 ± 0.1), Cu (4.0 ± 0.1), Zn (2.0 ± 0.1), Se (4.0 ± 0.1) and Pb (5.0 ± 0.1). The value for quantification limit for the five elements was 20 μg L −1, with 3% deviation. Multi-element standard solutions were prepared. Precipitation procedure was applied in the spiked solutions and the samples were filtered in cellulose ester membrane for quantification measurements. The optimum values obtained were 300 mL of sample solution, pH 4, 1 mL of 2% APDC and 10 min of stirring time. The concentration results obtained for the validation measurements were satisfactory for in situ survey employing a portable instrument.

Lead post-mortem intake in human bones of ancient populations by 109Cd-based X-ray fluorescence and EDXRF

In this work we measured the lead concentration in human bones of Middle Age by means of a portable X-ray fluorescence system based on 109Cd radioactive source. The detection system consists on a Ge hyperpure detector. This system, conceived for in vivo Pb analysis in bone, is portable, non-destructive and is based on lead K lines detection. The analysed bones are part of two collections of bones both from the end of Middle Age and submitted for some years to a lead polluted burial environment. The bones of one collection were buried initially on the soil in a convent, in Lisbon (Portugal) and further on, kept in a lead coffin for around 100 years. The second collection contains bones buried permanently on the soil around an old church on the south of Portugal. This place became a parking car for around 20 years. In this work we studied the distribution of Pb in cortical bone, and trabecular regions from the outside surface to the inner part of the bone and the results are compared with the obtained ones by energy dispersive X-ray fluorescence (EDXRF). The obtained values present a strong contamination of Pb in spongy bones kept in the lead coffin with concentrations ranging from 250 to 350 μg Pb/g bone mineral, and 4 to 7 μg Pb/g bone mineral for bones buried in the soil. Good agreement was observed between the results obtained by the two techniques.

Crime scene investigations using portable, non-destructive space exploration technology

The National Institute of Justice (NIJ) and the National Aeronautics and Space Administration’s (NASAs) Goddard Space Flight Center (GSFC) have teamed up to explore the use of NASA developed technologies to help criminal justice agencies and professionals solve crimes. The objective of the program is to produce instruments and communication networks that have application within both NASA’s space program and NIJ programs with state and local forensic laboratories. A working group of NASA scientists and law enforcement professionals has been established to develop and implement a feasibility demonstration program. Specifically, the group has focused its efforts on identifying gunpowder and primer residue, blood, and semen at crime scenes. Non-destructive elemental composition identification methods are carried out using portable X-ray fluorescence (XRF) systems. These systems are similar to those being developed for planetary exploration programs. A breadboard model of a portable XRF system has been constructed for these tests using room temperature silicon and cadmium-zinc telluride (CZT) detectors. Preliminary tests have been completed with gunshot residue (GSR), blood-spatter and semen samples. Many of the element composition lines have been identified. Studies to determine the minimum detectable limits needed for the analyses of GSR, blood and semen in the crime scene environment have been initiated and preliminary results obtained. Furthermore, a database made up of the inorganic composition of GSR is being developed. Using data obtained from the open literature of the elemental composition of barium (Ba) and antimony (Sb) in handswipes of GSR, we believe that there may be a unique GSR signature based on the Sb to Ba ratio.