Use Of Proton Induced X-ray Emission Research Articles

Editorial

Editorial

A Milliprobe for PIXE and PIGE Analysis used for the Study of Colour-Zoned Tourmaline

A “milliprobe” system was implemented by using the focusing properties of a Van de Graaff accelerator, together with a collimator system including 1 mm diameter apertures, to impose the appropriate dimension to the beam spot. The scanning of the sample surface was achieved by X-Y movements of the sample holder (the Z axis being coincident with the beam direction). These movements were accomplished by a motorised X-Y table, with a travel of 25 mm × 25 mm, connected to the sample holder.This system was used to study specimens of the mineral tourmaline. Two samples, of the “watermelon” zoned tourmaline variety, originating from the Alto Ligonha pegmatite district in northern Mozambique, were analysed by the simultaneous use of PIXE (Proton-Induced X-Ray Emission) and PIGE (Proton-Induced Gamma-Ray Emission) techniques, in order to quantify their composition and try to establish a correlation between the elements (major and trace elements) and colour zoning.In order to validate the “milliprobe” analysis and study in more detail the frontier between zones of different colours, a microprobe analysis of the samples was also done.In this work, the mineralogical classification of the samples was accomplished. A correlation was established between the presence of Fe and green colour. It was also concluded that the presence of Mn by itself is not enough to lead to pink colour, which gives support to previous studies that claim that only Mn3+ and not the more common form Mn2+ is responsible for the pink colour.

Comparison between proton-induced x-ray emission (PIXE) and total reflection x-ray fluorescence (TXRF) spectrometry for the elemental analysis of human amniotic fluid

A comparison between use of proton-induced x-ray emission (PIXE) and total reflection x-ray fluorescence (TXRF) techniques in relation to the elemental analysis of amniotic fluid (AF) was carried out by measuring the concentrations of Cl, K, Ca, Fe, Cu, Zn and Br. For 10 AF samples analyzed, the agreement between PIXE and a TXRF measurements was 100% for K, 60% for Cl and Ca, 80% for Fe and 50% for Cu. For Zn, although there was only a 20% agreement, the measured concentrations ranged between 0.1 and 1 μg/ml with a TXRF standard deviation as high as 0.070 μg/ml. For Br, a factor of 1.8±0.2 was obtained between TXRF and PIXE measurements, suggesting a systematic error between experiments. This work indicates that further investigation is required to determine the experimental conditions, e.g. sample preparation and irradiation, which lead to complete agreement between TXRF and PIXE when a complicated organic sample such as amniotic fluid is analyzed. Copyright © 1999 John Wiley & Sons, Ltd.

Use of proton-induced X-ray emission (PIXE) analysis in the evaluation of large volume parenteral rubber stoppers

The use of external beam proton-induced X-ray emission (PIXE) analysis for determining the elemental composition of three different types of rubber stoppers used to seal parenteral solutions is described. The stoppers were immersed in 0.9% sodium chloride solution in conical flasks. The flasks were then autoclaved in a pilot autoclave using an F o value of 15 min at 121°C. The PIXE measurements were performed at the 2.5 MeV Van de Graaff accelerator in the University of Helsinki. The results show that the PIXE method clearly revealed the differences between different types of rubber stoppers. The elements found were, e.g., Fe, Ti, Zn, Br. The limits of detection were 2 ppm for Ti, 6 ppm for Fe, 2 ppm for Cu, 1 ppm for Zn, 3 ppm for Br and 0.5 ppm for Pb. The concentrations of a certain element vary greatly from sample to sample, for example, that of Zn by a factor of 4000. The elemental compositions of 4482 PH 4001/45 and 4782 PH 4106/50 are nearly identical, whereas the elemental composition of 4443 PH 21/50 is more complicated. Heavy elements were either non-existent or present in very low quantities. PIXE analysis is useful for detecting and quantifying elements with atomic numbers greater than 12. A particular feature of the method is that many elements can be analyzed simultaneously if a detection system with sufficient resolution is available. The sensitivity of the method at the ppm level and the fact that analyses may be performed on samples of small size make it a promising technique for analyzing the chemical composition of rubber stoppers. This method could be used in various pharmaceutical applications, since analysis can be performed under a normal atmosphere without requiring the use of a vacuum.

Nuclear microscopy: biomedical applications

Recent developments in high energy ion beam techniques and technology have enabled the scanning proton microprobe (SPM) to make advances in biomedical research. In particular the combination of proton induced X-ray emission (PIXE) to measure the elemental concentrations of inorganic elements, Rutherford backscattering spectrometry (RBS) to characterise the organic matrix, and scanning transmission ion microscopy (STIM) to provide information on the density and structure of the sample, represents a powerful set of techniques which can be applied simultaneously to the specimen under investigation. This paper reviews briefly the biomedical work using the proton microprobe that has been carried out since the 2nd Int. Conf. on Nuclear Microprobe Technology and Applications held in Melbourne, 1990. Three recent and diverse examples of medical research are also presented from work carried out using the Oxford SPM. The first is a preliminary experiment carried out using human hair as a monitor for potential toxicity, using PIXE elemental mapping across the hair cross section to differentiate between elements contained within the hair and contamination from external sources. The second example is in the use of STIM to map individual cells in freeze-dried tissue, showing the possibility of the in situ microanalysis of cells and their extracellular environment. The third is the use of PIXE, RBS and STIM to identify and analyse the elemental constituents of neuritic plaque cores in untreated freeze-dried Alzheimer's tissue. This work resolves a current controversy by revealing an absence of aluminium levels in plaque cores at the 15 ppm level.

Proton-induced X-ray emission (PIXE) spectrometry — state of the art

The development of the PIXE method for multielemental analysis is described. A brief account is given of the physical principles and the experimental arrangements. The use of PIXE is illustrated by a number of typical applications in geology, biology, medicine and environmental research.

An application of PIXE in medicine: Legionnaires' disease

The name “Legionnaires' disease” refers to an acute respiratory illness that was first recognized at an American Legion Convention in Philadelphia in July, 1976. 221 people became ill and 34 died. During the ensuing months before the etiologic agent, a previously unknown species of bacterium, was isolated, many investigators suspected that a toxic agent, in particular nickel carbonyl, might have caused the outbreak of illness. We describe the use of proton-induced X-ray emission (PIXE) to analyse the nickel concentrations of the autopsy specimens. We show that the high nickel concentrations in the lung specimens were due to contamination during the autopsies. Recently we have used PIXE to show that the selenium concentrations in the serums of the acutely ill Legionnaires' patients are significantly lower than in their matching convalescent-phase serums. This finding may be related to the patient's response to the disease or to the specific characteristics of the Legionnaires' bacterium itself.

PIXE and the Mysteries of Legionnaires' Disease

We describe the use of proton-induced X-ray emission (PIXE) to analyse the nickel concentrations of the autopsy specimens from victims of Legionnaires' disease. We show that the high nickel concentrations in the lung specimens from the first recognized Legionnaires' cases in Philadelphia in 1976 were due to contamination during the autopsies. Recently we have used PIXE to show that the selenium concentrations in the sera of the acutely ill Legionnaires' patients are significantly lower than in their matching convalescent-phase sera. This finding may be related to the patient's response to the disease or to the specific characteristics of the Legionella pnewnophila itself. Studies show that the disease is not a rare illness but a worldwide one. General criteria concerning specimen collection are described.

Advances in the use of PIXE and PESA for air pollution sampling

Proton induced X-ray emission (PIXE) and proton elastic scattering analysis (PESA) are complementary ion beam techniques well suited to giving total elemental analysis of small samples. Air particulate samplers designed to yield ideal small samples have been developed at Florida State University to give size and time distributions of the particulates. The two methods are discussed using samples taken mostly at Kawecki Berylco Industries.

The use of PIXE for the measurement of thorium and uranium at μgg −1 levels in thick ore samples

Proton induced X-ray emission (PIXE) techniques have been used to estimate the concentrations of trace quantities of thorium and uranium in pelletised powdered rock and ore samples. A variety of naturally occurring ores with uranium and thorium concentrations in the range 10–10 000 μg g −1 have been studied. The lower level detection limit with no adjacent element interference was 3–4 μg g −1 per 100 μC. To verify the PIXE technique for thorium and uranium determination, the same batch of samples was measured by delayed neutron activation for uranium concentrations, and neutron activation analysis for thorium concentrations. They were in excellent agreement.

The use of proton induced x-ray emission in the design and evaluation of catalysts

In preparing a heterogeneous catalyst, it is usual practice to disperse one or more catalytic elements over a suitable high surface area support, such as porous alumina. It is very useful then to be able to monitor all the catalytic elements (and the trace impurities) within the crucial first few microns of the surface. The technique of proton-induced X-ray emission (PIXE) analysis is suited ideally to this purpose. The present work describes how it was used during the development of a new series of catalysts which were designed to be bonded to a special oxidation-resistant aluminium-containing steel, and used in vehicle exhaust emission control. In particular, we illustrate the use of PIXE in highlighting the relative resistances of different catalyst formulations to Pb poisoning.

Analytical use of proton-induced X-ray emission

Proton-induced X-ray emission, PIXE, is capable of simultaneous quantitative determination of 10–15 elements. An introduction to the physical properties of the method is given and detection limits are shown for a routine analysis of a thin aerosol sample. Examples of applications to both thick and thin samples are presented. Human tooth dentine is analysed for lead, with simple sample preparation, indicating lead values of a few ppm for Swedish children. Quantitative analyses of several other elements are obtained simultaneously. Cascade impactors are used for sampling aerosols in work environment during welding operations giving information of size distribution and concentrations of the elements present. The aerosol is dominated by particle sizes between 0.5 and 2 μm as measured by the impactor, but the size distributions are different for different elements and welding techniques and depend on the distance from the welding source. The relative abundance of the elements found in the aerosol indicates the presence of fractionation mechanisms.