Trace element analysis of maternal scalp hair by external beam proton-induced X-ray emission (PIXE)

We have constructed an external beam proton-induced X-ray emission (PIXE) system for trace element analysis of biological and environmental samples. Optimization of sample preparation and experimental PIXE set up has produced a rapid, accurate, sensitive, and reliable PIXE analysis procedure. The analytical procedure was evaluated using maternal scalp hair from pregnant women 16–19 weeks' gestation. The samples were irradiated with 3.5 MeV protons from the Rutgers Nuclear Physics Department's 8 MV Tandem FN Van de Graaff accelerator. The concentrations of the elements calcium (Ca) to cadmium (Cd) in hair are reported for 50 subjects. The analytical procedure is suitable for non-invasive clinical analysis for evaluation of nutritional states and for environmental exposure to toxic metals.     

Growth of hair and the trace element profile a study by sectional analysis

Correlations between the growth of hair and the trace element profile have been investigated by non-destructive neuron activation analysis through gamma-ray speetrometry using NaI(Tl) as well as Ge(Li) detectors. After preliminary investigations to establish the experimental errors, the effect of washing procedures and in-person variations, hair samples belonging to ladies with known case histories, particularly with regard to dietary habits, health and profession, were examined. Scalp-hair samplex 50–100 cm in length, representing an average time span of ∼5–10 years were collected by combing. Samples in their non-anagen phase, differentiated by their roots, were analysed in 10 cm sections. The concentrations of the following elements were determined: Na, Cl, Mn, Co, Cu, Zn, As, Se, Ag, I, Au and Hg. Absolute values for the concentrations are reported for most of the elements, while for the rest relative values for the various sections are given. The values for the different sections vary by large factors for many elements although for some elements, like Cu and Mn, the variations are not appreciable. The unusually large concentrations of elements like Se ang Hg are in broad agreement with the case histories. However, detailed examination of the results with regard to time-dependent variations seem to pose serious problems in the applications to forensic science.     

Nuclear-based methods for the analysis of trace element pollutants in human hair

The trace element composition of human hair is a suitable indicator of exposure to trace element pollutants. During the implementation of an international research programme, coordinated by the IAEA, on the use of nuclear methods for detecting trace element pollutants in hair, much valuable information was collected both on normal levels of trace elements and on increased levels caused by pollution. As a result of reviewing and comparing the data, interesting observations relating to the spread of concentrations were made. Standardized procedures were elaborated for a number of analytical techniques as well as for pre-analytical preparations in the analysis of hair. Paper presented at the Second Meeting on Nuclear Analytical Procedures, Dresden (GDR), 19 to 23 March 1979.     

Quality control in hair analysis: A systematic study on washing procedures for trace element determinations

Trace element analysis of human hair is widely used to provide an indicator of body burden, but there is a major problem associated with preparation. The washing procedure adopted before analysis represents still a critical point which deserves particular attention. This study aimed at comparing the efficiency of the most commonly used washing methods to identify the procedure which allows for satisfactory removal of external contamination alone. As results depend strongly on the element, toxic (Cd and Pb), essential trace (Cr, Cu, Se and Zn) and major (Ca, K and Mg) elements were tested. The comparison was carried out with six different methods which include use of ionic and non-ionic detergents, organic solvents, chelating agents and sonication. Removal efficiency varied according to the element and pretreatment, the highest being observed for EDTA and the lowest for sonication. Unsatisfactory results were found using an acetone/methanol mixture for the potential contamination caused by it. Organic solvents showed the highest removal efficiency for K and toxic elements, and seemed to be effective in removing a limited but significant fraction of element incorporated in the lipid matter of hair. The ionic detergent Na lauryl sulphate, instead, was more effective for essential elements, but also triggered a higher analytic variability. As detergents appear to remove only external contamination, a non-ionic detergent such as Triton X-100 is proposed as a reliable alternative to the acetone method recommended by IAEA. Practical advantages are safe working conditions, rapidity of application and reduction in costs.     

Determination of major and trace elements in bones by simultaneous PIXE/PIGE analysis

The training process and training programs in both commercial nuclear plants and Department of Energy (DOE) nuclear facilities have improved significantly in the years following the Three-Mile Island (TMI) accident. This article describes some of these changes, including the reasons behind the change, the affected population, the training accreditation process and performance-based training, and the benefits of the changes.     

PIXE analysis of the hydrothermal leaching of trace elements in coal

The minor and trace element content in coal is of great interest due to the potential impact on the environment from the release of these elements during combustion. Reducing the concentrations of potentially hazardous elements in coal prior to combustion is one way of dealing with this issue. In this research particle induced X-ray emission (PIXE) was used to investigate a hydrothermal leaching process for the removal of trace elements from a bituminous coal. The leaching agents HNO₃ and NaOH were evaluated along with the effects of process parameters (temperature, pressure, and time) on the method's effectiveness. The variable with the greatest influence was the leaching agent itself. HNO₃ was determined to be more effective than NaOH in reducing elemental concentrations for nearly all the elements determined. Increasing the temperature did result in greater reductions for some elements (Cl, Br, Zn) whereas increasing the pressure and duration of the leaching process had minimal impact on reductions, in elemental concentrations.     

Determination of trace element levels in human scalp hair in occupationally exposed subjects by XRF

Trace element levels in hair of individuals living in urban areas were determined by energy dispersive XRF. Two groups of subjects were investigated, the first group was assumed to be from a healthy environment, the other one was exposed to a high level of contamination due to working conditions. The results were compared to data reported in the literature. The concentrations of Ca, Fe, Cu, Zn and Pb in the scalp hair were determined and the correlation between hair trace element levels and environmental effects was discussed. The results given by the second group show that environmental exposure effects hair trace element levels which are related to body trace element concentrations.     

Application of PIXE analysis to environmental samples stable element distribution in sea algae by scanning microprobe analysis

The resolution of a 33±3 m microprobe focussed with quadrupole doublet installed at the 3 MV Van de Graaff of the National Institute of Radiological Sciences was used for this analysis. Brown algae, Hijiki,Hizikia fusiforme was the sample target bombarded with a 2 MeV proton beam collimated mechanically into a rectangular image of 100 m × 700 m. Scanning across the sample target prepared into a longitudinal section from the caulis of the algae provided the following observations. More than 12 elements such as Al, Si, P, Cl, Ca, Mn, Fe, Cu, Zn, As, Br and Sr were determined simultaneously, together with their distributional information across the diameter. In the medullary layer, Mn and Zn were specific in their accumulation, while the deposition of Fe, Cu, As and Br were observed to be high in the epithelial layer, especially Fe and Cu which were found on the surface, where they contact ambient sea water, but no significant change in pattern was indicated for such elements as Al, P and Cl. The PIXE microprobe analysis was, therefore, effective in its detectability for elements below a few ppm level, resultantly provides further possibilities for collecting information from bio-medical and environmental samples on trace characterization of elements.     

Estimation of trace elements in some anti-epileptic medicinal plants by PIXE

Trace elemental analysis was carried out in various parts of 10 anti-epileptic medicinal plants using PIXE technique. A 3?MeV proton beam was used to excite the samples and spectra were recorded using a Si(Li) detector. Data analysis was done using Gupix Software. The elements Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Br and Sr were identified and their concentrations estimated. The presence of some of these trace elements is correlated with the anti-epileptic curative property of these plants.     

The effect of washing procedures on trace element content of human hair

The effects of four washing procedures on the concentrations of manganese, iron, copper, zinc and cadmium and were investigated for three pooled samples of human head hair. The solutions evaluated were a non-ionic detergent (Triton X-100), an ionic detergent (sodium lauryl sulfate), acetone and a complexing agent (EDTA). The results indicate that for every element determined there is a level below which the concentration cannot be reduced by further washings. The numbers of washings required to reach these levels vary considerably. This effect must be considered in the trace element analysis of hair.     

The cluster analysis technique of pattern recognition: application to the trace metal composition of cardiovascular tissues.

Application of the statistical method of cluster analysis as a pattern recognition technique was investigated by classification of cardiovascular tissues on the basis of their trace metal composition. The distribution patterns of 13 trace metals among 17 tissues of the heart and its appended blood vessels were determined. Cluster analysis of the data resulted in ready differentiation of tissues derived from ordinary and specialized myocardium from those of blood vessels and heart valves. Further similarities and differences among the 17 tissues were identified by comparing the patterns generated when different numbers of groups (i.e., 3, 4, 5, 6, and 7 groups) were designated. It is suggested that cluster analysis may provide a generally useful tool in the interpretation of data from multi-phasic laboratory testing procedures.     

Use of PIXE analysis to determine trace metals in drinking water in Jordan

The procedure for using proton induced X-ray emission (PIXE) in conjuction with the method of spotting for qualitative and quantitative multi-element analysis of drinking water in eight cities of Jordan is discussed in this article. It is likely that this method of preconcentration can be directly incorporated into field sampling procedures, thus eliminating the problems of sample contamination or trace element losses by absorption on container walls, the significance of some of the elements found in the samples is discussed.     

Radionuclide dating and trace element analysis by accelerator mass spectrometry

Accelerator Mass Spectcrometry (AMS) is being used for both radionuclide dating and stable isotope trace element determination with limits of high sensitivity. The areas of applications of radionuclide AMS include oceanography, terrestrial studies, glaciology, hydrology, environmental studies, meteorology, archaeology, anthropology, analysis of crude oils, biomedical and materials sciences, etc. The techniques and applications of radionuclide AMS are reviewed. The applications of stable element AMS include the measurements of trace impurities in electronic and other materials. The techniques and applications of stable element AMS are discussed with particular emphasis on electronic materials such as Si, GaAs, and HgCdTe. The design of the University of North Texas stable element AMS facility built in collaboration with Texas Instruments Incorporated is discussed.Work supported in part by the National Science Foundation Grants No. DMR-8812331 and ECD-9003099, the Office of Naval Research Grants No. N00014-89-J-1309, N00014-89-J-1344, N00014-90-J-1691, and N00014-91-J-1785, Texas Instruments Incorporated, Texas Utilities Electric Inc. International Digital Modeling Corp., North Texas Research Institute, Combustion Engineering Inc., LTV Corporation, the State of Texas Higher Education Coordinating Board — Texas Advanced Technology Research Program, the Robert A. Welch Foundation, and the University of North Texas Organized Research Fund.     

Certified reference material (CRM 397) for the quality control of trace element analysis of human hair

Summary Analyses of human hair are routinely performed by a number of organisations to monitor the level of exposure of a population to toxic elements, e.g. heavy metals. To control the quality of such determinations, the Community Bureau of Reference (BCR) has produced a reference material (CRM 397) certified for its contents of Cd, Hg, Pb, Se and Zn. This material was collected in a moderately contaminated area, carefully prepared and its homogeneity and long term stability were verified. This paper presents the certification work performed.     

Single-crystal trace element analysis in rock-forming minerals by instrumental neutron activation analysis

We have developed an INAA techniques for analyzing single crystals extracted from rocks. Trace element contents have been measured in a large variety of mineral species, as well as isotopic ratios of some REE in minerals related to natural fission reactions. The sensitivity of INAA allows to avoid the main shortcomings of usual mineral geochemistry: (1) only very short quantities of minerals are needed (down to a few g), so that even very sparse minerals could be analyzed, (2) purity of minerals is carefully checked, and (3) the heterogeneity of a population may be studied. The method is especially useful when applied to minerals acting as tracers for some element families, e.g. REE in Ca-bearing minerals (fluorite, apatite, titanite, gamet) and Zr-bearing minerals, or chalcophile elements (Co, Ni, As, Sb, Mo, Ag, Au and Se) in sulfides. We present an application of the method to the Oklo U deposit in Gabon showing that features outlined above are of special interest for the study of hydrothermal processes.     

XRF induced by PIXE: Comparison with PIXE

Two different modes of sample excitation have been used for elemental analysis of thin standard reference materials and of chemical standards with known composition. PIXE /2.5 MeV protons/ and XRF induced by PIXE, will be called XRF-PIXE /2.5 MeV protons on Mo primary target/. The same samples were alternatively exposed to protons and X-ray beams. The sensitivities under standard running conditions are determined for both an XRF-PIXE and a PIXE analysis system. It is shown that the sensitivity of the PIXE spectrometer depends strongly on the sample matrix, whereas the XRF-PIXE sensitivity is rather constant with respect to different kinds of samples. In addition, the advantages of one mode of excitation on the other are discussed. It is shown that XRF-PIXE can be a useful complement to PIXE analysis.     

Trace analysis of lithium metal by PIXE

A rapid method is described for simultaneous trace determination of metallic impurities in lithium metal by Particle Induced X-ray Emission (PIXE) technique. The impurities were preconcentrated by ion-exchange separation using a weak cation exchanger, Bio Rex-70 and analyzed by 2.34 MeV protons. The reliability of the method was tested by analyzing synthetic samples having several metallic impurities at 1–5 ppm range.