The determination of the elemental composition of glasses for forensic application using a combination of proton induced X-ray emission and inelastic proton scattering

Proton induced X-ray emission (PIXE) is used in an attempt to identify glass samples with the aid to determine, trace element concentrations. The elements Na and A1 are simultaneously determined using the (p, p' γ) nuclear reaction. The preparation of very thin and homogeneous glass targets is discussed and a procedure is described to obtain an accurate equipment calinration, checked afterwards with NBS bovine liver. Results are given for 11 different glass samples.     

Elemental composition of skin tissue by PIXE and INA analyses

Hypertrophic scars are a particular type of scar that can form after any type of dermal injury. They are unsightly, red, elevated above nomal skin level, itchy and painful. At present no-one knows why these scars form. Due to the differences between scar tissue and normal skin it was decided to analyse skin tissue which at a later date would be compared to scar tissue. Split skin graft (epidemis) samples as well as full thickness skin (epidemis to demis) tissue were analysed using PIXE and RBS with a 2 MeV proton beam. The epidemis was compared to the demis to see if there were any variations between the two. In all the samples P, S, Cl, K, Ca, Fe, and Cd were detected and in a majority of the samples Zn and Ba were found, using PIXE. It was found that, between the epidemis and demis, there was an significant increase in P in the epidermis in both full thickness and split skin graft samples. Complementary elemental analysis was also performed using neutron activation, and Br, Na and Zn were detected.     

Elemental distribution in breast tissue samples using X-ray fluorescence microtomography

Summary The X-ray fluorescence microtomography (XRFMT) is a non-destructive technique, based on the detection of X-ray fluorescence emitted by the elements in the sample, and it is used to complement other techniques for sample characterization. In this work some tissues of human breast (healthy tissue, benign tumor and malignant tumor) have been analyzed in order to verify the efficiency of the system in the determination of the elemental distribution in these types of samples. The experiments were performed at the X-ray fluorescence beam line (D09B-XRF) of the Brazilian Synchrotron Light Source (LNLS), Campinas, Brazil. A white beam was used for the excitation of the elements and an HPGe detector detected the fluorescence photons. The incident beam was monitored by an ionization chamber and a fast scintillator detector was used to detect the transmitted radiation. All the tomographies have been reconstructed using a filtered-back projection algorithm. In the tissues samples, the elements of higher concentration were Zn, Cu and Fe.     

Elemental composition determination of organophosphorus compounds using gas chromatography and atomic emission spectrometric detection

The elemental responses for a series of alkylated and arylated phosphates evaluated were measured on an atomic emission spectrometric detector. The signals for carbon, hydrogen, chlorine, phosphorus and oxygen were used to determine the specifity of elemental response ratios to a particular compound structure and the dependence of response ratios on the amounts of the analytes. Variations of the response ratios, as well as the accuracy and variations of the stoichiometric values of the calculated empirical formulae, were evaluated. For this purpose, a test mixture with reference compounds was used. Determination of empirical formulae with acceptable errors of a few percent is possible if the calibrating reference substance is closely related — by structure, elemental composition, molecular weight and amount — to the compounds to be identified. Analyte amounts of at least 30 ng are required for efficient calibration.     

Assessment of atmospheric deposition of metals in Ha Noi using the moss bio-monitoring technique and proton induced X-ray emission

Journal of Radioanalytical and Nuclear Chemistry - The concentration of 22 metal elements including Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr, Zr, Ba and Pb in Barbula...     

Chemical speciation of chlorine in atmospheric aerosol samples by high-resolution proton induced X-ray emission spectroscopy

Chlorine is a main elemental component of atmospheric particulate matter (APM). The knowledge of the chemical form of chlorine is of primary importance for source apportionment and for estimation of health effects of APM. In this work the applicability of high-resolution wavelength dispersive proton induced X-ray emission (PIXE) spectroscopy for chemical speciation of chlorine in fine fraction atmospheric aerosols is studied. A Johansson-type crystal spectrometer with energy resolution below the natural linewidth of Cl K lines was used to record the high-resolution Kα and Kβ proton induced spectra of several reference Cl compounds and two atmospheric aerosol samples, which were collected for conventional PIXE analysis. The Kα spectra which refers to the oxidation state, showed very minor differences due to the high electronegativity of Cl. However, the Kβ spectra exhibited pronounced chemical effects which were significant enough to perform chemical speciation. The major chlorine component in two fine fraction aerosol samples collected during a 2010 winter campaign in Budapest was clearly identified as NaCl by comparing the high-resolution Cl Kβ spectra from the aerosol samples with the corresponding reference spectra. This work demonstrates the feasibility of high-resolution PIXE method for chemical speciation of Cl in aerosols.     

Determination of fluorine concentrations in soil samples using proton induced gamma-ray emission

A non-destructive, in situ current normalized particle induced gamma-ray emission methodology has been standardized for quantification of fluorine (F) in soil samples from Punjab state, India. The samples were irradiated using 4 MeV proton beam from the Folded Tandem Ion Accelerator at BARC, Mumbai. The gamma rays of energies 197 and 478 keV arising from ¹⁹F(p, p′γ)¹⁹F and ⁷Li(p, p′γ)⁷Li nuclear reactions were measured using high resolution gamma-ray spectrometry. The concentration of fluorine in soil samples was found to vary between 414 and 5,746 mg kg^?1.     

Application of proton induced X-ray emission to the qualitative and quantitative analysis of iodine in biological samples

Particle-induced X-ray emission (PIXE) was applied to evaluate the loss of volatile elements such as iodine in biological samples. The analytical quality of the method is comparable or better than spectrophotometry, which is currently believed to be the most reliable for iodine determination. The temperature dependence of volatility loss of trace iodine was characteristic, and the feature was divided into three temperature regions. The first one, ranging from room temperature to 200 °C, showed only a slight loss below 20% on drying; the second stage, between 200 °C and 350 °C, where carbonizing processes became prominent, showed a remarkable loss up to 50%; the last one, beyond 350 °C, was accompanied by a considerable loss of iodine (more than 80%) with ashing. Even in the analysis using low temperature ashing with oxygen plasma, the loss of iodine observed was considerable (nearly 80%). The significance of these findings by PIXE in trace analysis is noted to improve analytical quality of volatile elements, such as iodine in biological, medical and also environmental fields.     

Error reduction in simultaneous proton induced X-ray emission tomography and on/off-axis scanning transmission ion microscopy-tomography

Rapid micron-resolution quantitative elemental mapping is possible at the University of Surrey using a combination of proton induced X-ray emission tomography (PIXE-T) and simultaneous on/off-axis scanning transmission ion microscopy-tomography (STIM-T). A preliminary analysis of hair was performed. However, experimental uncertainties lead to large errors in tomograms and this work focuses on identifying and reducing the sources of error in both tomographic and 2D mapping. The STIM-T counts per pixel are used to normalise the PIXE-T data for charge. However, the geometry of the collimator and the scattering foil affects the detection rate since the loss of protons in the collimator increases as energy loss increases due to scattering. Errors in the PIXE geometric efficiency are greater in mapping when the detector is close to the sample. Moreover when a ‘funny’ filter was used for PIXE-T the uncertainty in the efficiency was found to increase because the sample-filter distance changes during the experiment.     

Trace element study of human bone by X-ray emission analysis using an external proton beam

A simple proton beam (PIXE) arrangement developed for a low energy accelerator was used for the determination of absolute concentrations of nine trace elements in human bone samples. The 2.4 MeV proton beam was externalized through a thin (2 μm) aluminiummylar foil. Using an air cooling system, the foil withstood a high current (0.5–1 μA) for a long time. The samples were cooled to prevent damage and volatilization of elements. The induced X-rays were detected with a Si(Li) detector and the external beam was monitored with a second detector, measuring K X-rays induced in atmospheric argon. The mean (SD) trace element levels (ppm) measured in dense bone by comparison with hydroxyapatite/standard mixtures were: Cr<2.0, Mn<2.3, Fe 7.58 (1.55), Ni<2.4, Cu 3.58 (2.16), Zn 144 (27), Pb 12.2 (2.5), Br 12.4 (5.5) and Sr 47.7 (14.3). The detection limits for these elements achieved in this work were about 1 ppm when rather short measuring times (∼10 min) were used. The coefficient of variation of a single measurement, e.g. for Zn, was 3–4%. Because of the slow turnover of dense bone, such measurements provide a means of monitoring long term trace element exposure.     

Determination of the elemental homogeneity of selected biological organs by 2MeV proton induced X-ray emission analysis

The use of finite size sub-samples to derive elemental concentrations which are representative of a tissue or organ as a whole are subject to errors arising from the heterogeneous nature of biological specimens. Proton induced X-ray emission (PIXE) analysis is employed to identify element variances in porcine liver, kidney and heart and sampling factors, which are the minimum mass of sample required to reduce concentration variability to a given level, are calculated. This analysis highlights the inhomogeneous nature of biological specimens and the need for clearly defined sampling protocols.     

Analysis of blood serum of lung cancer patients using particle induced X-ray emission

Trace elemental imbalance in human beings is postulated to exert action, directly or indirectly, on the carcinogenic process. The objective of this study was to evaluate the levels of trace elements in blood serum samples of lung cancer patients and analyze their alteration with respect to healthy controls. Particle induced X-ray emission (PIXE), a well established method for elemental analysis, was used to identify and quantify trace elements in the blood serum samples of the studied groups. The PIXE measurements were carried out using 2.5 MeV collimated proton beam from the 3 MV Tandem Pelletron Accelerator at Ion Beam Laboratory, Institute of Physics, Bhubaneswar, India. The serum of the cancerous group displayed increased concentrations of Ti, Ni, and Cu but lowered concentrations of V, Cr, Mn, Fe, Co, Zn, and Se. Statistically significant differences were found for serum Cr (p < 0.01), Fe (p < 0.0005), Ni (p < 0.05), Cu (p < 0.00005), and Zn (p < 0.0005) between the two studied groups. The copper to zinc ratio for the lung cancer group was 2.24 ± 0.39, which was almost three times the value for normal subjects (0.77 ± 0.14). The observed alterations are discussed with respect to the possible mechanisms by which these elements might influence the carcinogenic process. Significant reduction in mortality from lung cancer can be achieved by advances in early diagnosis and implementation of multidisciplinary treatment programmes leading to improvement of survivorship and better quality of life. It is expected that similar studies from all corners of the world would ultimately lead to the development of novel therapeutic agents to treat lung cancer.     

Trace element determination in tomato puree using particle induced X-ray emission and Rutherford backscattering

Particle induced X-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) were used to determine the concentrations of trace elements in samples of 12 tomato puree brands sold in the Mexican market. While RBS offered information about the main elements present in the matrix, PIXE gave results on trace elements. As a whole, data for 17 elements (C, N, O, Na, Mg, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn) were obtained. To evaluate the results, a comparison with brands from USA, Japan, Colombia, and Chile was carried out, using tomato purees produced following the domestic technology recipe. Additionally, the results were considered in the light of the Codex Alimentarius and the Mexican standard. It was found that all of the brands fall within the limits established by these standards, being of the same order of magnitude as the foreign brands. This revised version was published online in July 2006 with corrections to the Cover Date.     

Determination of selenium in animal tissue samples using radioisotope induced X-ray fluorescence

A summary of sources of background affecting gamma-ray spectrometers and methods for eliminating each are discussed, along with practical cost/benefit ratios. Background contributed by samples generally defines practical levels for system background. The practical bottom line can be obtained for relatively modest costs. A realistic bottom line is attained in underground systems when the major contributions to the background come from cosmogenically produced⁶⁸Ge and double-beta decay of⁷⁶Ge in the detector. The true bottom line is reached with isotopically enriched detectors that eliminate these two chemically inseparable radioactive impurities. Data from isotopically enriched detectors are presented.     

Photon and proton induced X-ray cross sections for some elements

The cross sections for the production of K and L shell x-rays in some elements by monoenergetic photons have been measured and the experimental values were compared with the theoretical values. Also, the K shell x-ray production cross sections have been measured for thin targets of some elements by protons over the energy range 1.5–3.0 MeV. The ionisation cross sections were calculated and compared with Johansson's empirical formula.     

Using micro-synchrotron radiation induced X-ray emission distribution maps to determine correlation between elements in prostate tissue

Elemental maps obtained by micro-synchrotron radiation induced X-ray emission technique can be manipulated in several ways to extract useful information. In this paper the method of displaying the correlation between two or three elements in one correlation map is described. Such types of maps give precise information about the overlap between the elements without distorting the original data.     

The capabilities of proton induced X-ray fluorescence in analytical chemistry

The possibility to use proton induced X-ray fluorescence in trace analysis is investigated. Sensitivities and detection limits for elements from Z=24 are determined. The influence of a NaCl matrix on these parameters is measured and some possibilities are given to use the technique in analytical practice.     

Elemental analysis of fertilizers using X-ray fluorescence and their impact on alpha radioactivity of plants

The fertilizers used for plantation contain different elements including some natural radionuclides with their daughter decay products. The radiological impact of the use of fertilizers may be due to internal irradiation of the lung by the alpha particles, short lived radon-thoron progeny and the external irradiation of the body by gamma ray emitted from the radionuclides. The aim of this study was to estimate the enhanced alpha radioactivity in different parts of plants due to fertilizers and to measure the concentration of different elements present in the fertilizers. A control study was carried out on round gourd plants using different fertilizers. Fertilizers were added to the soil just before the plantation of seeds in the pots. For the measurement of alpha track densities in different parts of plants we used α-sensitive LR-115 type II plastic track detectors. The alpha-track density (T cm^?2 days^?1) was measured in leaves of plants at different interval of time. The variation in alpha track densities was also observed in root, stem leaf and grain parts of the plants. In case of the plants grown using some phosphate fertilizers the alpha radioactivity was found to be more compared with others. A positive correlation between alpha track densities and mass exhalation rates of radon from different fertilizers has been observed. The concentration of major elements (Al, Si, P, S, Cl, K) along with other elements present in fertilizer samples was measured by X-ray fluorescence analysis.     

A study on proton induced X-ray analysis and its application to environmental samples

Proton induced X-ray analysis has been studied by the 5 MV Van de Graaff of Tohoku University emphasizing on backing materials and angular dependence of background. The method has further been applied to analyses of some environmental samples. From experimental results, it was found that 4 μm Mylar foil among Formvar, Mylar and carbon gives sufficiently low background spectrum, high sensitivity and good mechanical strength. The detection limit is much improved at the backward direction with respect to the incident beam comparing with that at 90° which has usually been adopted. The analytical results on soil and aerosol samples were compared with those by the Atomic Absorption Spectrophotometrical method (AAS). Vanadium can easily be analysed by this method, but not by the AAS method. Milk and human milk were also analysed.