International Journal of PIXE

The status of the field of analysis of biological material using PIXE and complementary ion beam techniques are discussed. The development of PIXE with relevance to biology and the future prospects of Bio-PIXE are described.

A definition of biological essential elements was proposed. Their origin and function in human body were discussed. An excellent strain Sl of Tetrahymena, a kind of ciliates, has been used in this study to observe both stimulation or nutritious and toxic inhibition effects of elements located in s block, p block, d block, and f block in the periodic table, some regularity between the biological effects of these elements and their positions in the periodic table has been obtained. It is shown that a “spectrum of biological element equilibrium”, which exists in organism, can be exhibited in the periodic table designed in the three-dimensional space, if the abundance of biological elements or/and their bioavailability is used as the third z axis, a vertical line to the plane of the periodic table, and then the biological element spectrum shows that the exchanges of matter and energy between organism and surface environment of the earth have reached the dynamic equilibrium state. It seems that not only physical and chemical properties of different elements and compounds, but also their biological properties to a certain extent can be shown in the developed periodic table.

We measured continuum x-rays from an aluminium target bombarded with 60 keV- and 80 keV- proton beams. On the basis of the PWBA theory, we calculated the thick target yields of atomic bremsstrahlung and nuclear bremsstrahlung produced in very low energy ion-atom collisions and compared with the experiment. The present theory predicts that the main component of continuum x-rays produced in such low energy ion-atom collisions is the nuclear bremsstrahlung. The theory presents the yields of continuum x-rays about 5 times larger than the experimental ones, however, reproduces well the spectral shape.

L-shell X-ray production cross sections for selected heavy elements (Tl, Pb, Bi), of interest in BIO-PIXE analyses, have been measured by proton and ⁷Li ion impact in the energy range 0.8–2.6 MeV and 1.8–3.3 MeV respectively. Further, production cross sections for ⁷Li ion impact on Au between 1.0 and 2.4 MeV have been measured. L-subshell ionization cross sections have been extracted and arranged, together with similar results from other laboratories, in an analysis aiming at testing the performance of various theoretical approximations in the description of the ionization process. The disagreement observed at low values of the reduced velocity parameter ξ^R_L between the data and the predictions of the ECPSSR model is significantly reduced by using a United Atom approximation in the treatment of the binding correction, suggested by our group (ECPSSR-UA). The remaining discrepancies, mostly for the L₁-subshell, are almost completely removed by replacing the screened hydrogenlike wave functions with the more realistic Dirac-Hartree-Slater ones. In the case of ⁷Li ions, especially for L₂-subshell, also a more refined Coulomb deflection correction and more sophisticated coupled channel calculations are needed.

In the contribution the high-resolution X-ray spectrometer, originally constructed for the atomic physics research, is presented. Test measurements of Lβ and Lγ intensity ratios on In and Te compounds were performed. The applicability of the spectrometer for detection of chemical effects in X-ray spectra of compounds is discussed.

The continuous X-ray of Be, Ni, and Cd targets induced by N⁺, N²⁺, N³⁺ ions were measured at the projectile energies of 50-, 70-, 100-, 150-, and 200-keV. Since the energy of the projectile is so low and the detecting limit of the detector is about one keV, the continuous X-ray would be the X-rays of nuclear and atomic bremsstrahlung (NB, AB). From the result of maximum energy of ħω. the relationship of a maximum energy ħω of below:

The mechanism of vacancy distribution in C⁺−B, C⁺−N, C⁺−Be, and C⁺−O ion-atom collision process is studied in this paper based on molecular orbital theory. It translates intensity ratio of X-ray and Auger decay in ion-atom collision process.

About 40 subjects of PIXE have been studied in various research fields at Nishina Memorial Cyclotron Center (NMCC), and many satisfactory results have been obtained and reported. As the results, samples to be analyzed are highly diversified both in form and in elemental composition. Among them, samples most hard to be dealt with by PIXE are ones which contain a great quantity of specific elements. In order to solve this problem, we have developed and tried various absorbers which are specially designed for each kind of sample and are capable of decreasing some distinguished x-ray peak and making x-ray spectra gentle-sloping. It is found that not only the measuring time is fairly shortened but also highly sensitive and highly accurate analysis can be performed for each sample only by selecting absorbers.

A newly constructed chamber for measuring with MeV proton beams at small incidence angles (0 to 35 mrad) is used to analyse trace elements on flat surfaces such as Si wafers, quartz substrates and perspex. This set-up is constructed in such a way that the X-ray detector can reach very large solid angles, larger than 1 sr. Using these large solid angles in combination with the reduction of bremsstrahlungs background, lower limits of detection (LOD) using TPIXE can be obtained as compared with PIXE in the conventional geometry. Standard solutions are used to determine the LODs obtainable with TPIXE in the optimized setup. These solutions contain traces of As and Sr with concentrations down to 20 ppb in an insulin solution. The limits of detection found are compared with earlier ones obtained with TPIXE in a non optimized setup and with TXRF results.

We describe characteristics of high-resolution, wavelength-dispersive crystal spectrometers equipped with a different type of position sensitive X-ray detectors: PSPC, CCD, IP and MCP. Utilities of these position sensitive spectrometers in PIXE experiments are demonstrated by referring several recent topics of elemental analysis, chemical state analysis and a study on sample charging.

PIXE research at the 4.5-MV Dynamitron laboratory of the Faculty of Engineering, Tohoku University started as a joint project between Cyclotron and Radioisotope Center(CYRIC), Tohoku University, and the Dynamitron laboratory. The PIXE equipments including vertical beam in air PIXE system called ViaPIXE was installed at a vacant beam course of the Dynamitron laboratory. Some PIXE experiments conducted at this facility as well future PIXE research in this laboratory are briefly described.

The preparation of a biological sample using a microtome cryostat was attempted. The biological specimen was previously frozen with a freezing compound and an optimum section thickness was cut for PIXE analysis. First, bovine liver powder which was made into a paste with indium solution as an internal standard was prepared using the sectioning method. The concentrations of trace elements including volatile elements in the sample were determined and agreed with the certified values. Next, a mouse liver was prepared using the sectioning method. A polyphenylene sulfide (PPS) film containing a constant areal density of sulfur was used as a backing material for quantitative analysis. The concentrations of trace elements in a mouse liver prepared using the sectioning method were compared with those using the ordinary nitric acid method. The concentrations of some volatile elements were determined only in the sample obtained using the sectioning method. The preparation method using a microtome cryostat can be used to prepare a biological sample for PIXE analysis.

We have developed a software system based on the pattern analysis method in order to realize the automatic and quick PIXE spectra analysis. The software system was applied to some PIXE spectra to test the present method. Through the tests, important knowledge was obtained and some notions were adopted to the system.

Si-PIN photodiode type detector is one of the X-ray detectors which have recently shown significant improvement in resolution of FWHM of 250 eV at 5.9 keV which is worse only by 130 eV than that of a conventional type Si(Li) detector. The remarkable advantages of the SPINP detector are high operability with the thermoelectric cooling system and low voltage bias, and small volume including the preamplifier system. It is found that SPINP detector is applicable to the X-ray spectrometry and also PIXE in the X-ray energy range below about 15 keV with a reasonable efficiency. The pattern analysis method is feasible to analysis such bad resolution spectra obtained with this detector. Some techniques related to the Si-PIN photodiode type detector in Bio-PIXE are discussed.

Trace elements in ancient Chinese ink, ancient Chinese paper of sutras, ancient Japanese paper of manuscripts, modem Japanese paper and some plants were analyzed by PIXE. Part of these samples were carbonized at 400°C in vacuum of several torrs. These carbonized biological samples were able to resist very high current of 2 MeV He⁺ (500 nA/mm² on target) for more than 30 minutes. The observation indicates that the carbonized samples save the measuring time by using high beam current. But mercury and sulfur contained in red Chinese ink on the paper were lost through the carbonization and lead in the same sample was lost by heating up during the measurement on condition that it was irradiated by 2 MeV He⁺ (50 nA/mm² to 230 nA/mm²). A small part of iron was gradually lost on the same condition. Under 230 nA/mm², a small portion of calcium was lost but no portion of chromium was lost.

The material composition and surface structure of dental and orthopaedic implants influence the integration in bone, and, at the same time, the release of the constituent elements of the implants into the surrounding tissues. Titanium, titanium alloys (Ti-6Al-4V) and other materials which are considered to be biocompatible materials, release metal ions into the surrounding tissues. This may affect the appropriate biological response of the tissues to the implanted materials. The toxicity of some of the constituent elements of these implants, e.g. vanadium, is a matter of serious concern. In this paper, the experimental data on application of PIXE to biomedical-implant research are presented. Two groups of samples were prepared for PIXE analysis. The first group consisted of the specimens that were retrieved from the tissues around implants in 28 rats. The second group consisted of specimens that were sliced and polished to a thickness of a few 10 µm, while keeping the interface between the implant, cortical bone, bone marrow, and soft tissues intact. The implants of the second group, 10 specimens with between 6 and 20 measurement points on each specimen, were used for specifically obtaining the distribution of the released elements with reference to the implant tissue interface, using ion micro beam. The implantation time ranged from 12 weeks to 52 weeks.

This paper reviews the recent progress of the nuclear microprobe technology in both micro-analysis and micro-imaging. Some features of the nuclear microprobe facilities established at the Shanghai Institute of Nuclear Research and Fudan University are described Four examples of recent applications are enclosed to show the potentialities of the technique for a variety of scientific studies.

To investigate the cause of Alzheimer’s disease (senile dementia of Alzheimer’s disease type), we examined aluminium (Al) in the brain (hippocampus) of patients with Alzheimer’s disease using heavy ion (5 MeV Si³⁺) microprobe particle-induced X-ray emission (PIXE) analysis. Heavy ion microprobes (3 MeV Si²⁺) have several times higher sensitivity for Al detection than 2 MeV proton microprobes. We also examined Al in the brain of these patients by energy dispersive X-ray spectroscopy (EDX). (1) Al was detected in the cell nuclei isolated from the brain of patients with Alzheimer’s disease using 5 MeV Si³⁺ microprobe PIXE analysis, and EDX analysis. (2) EDX analysis demonstrated high levels of Al in the nucleolus of nerve cells in frozen sections prepared from the brain of these patients. Our results support the theory that Alzheimer’s disease is caused by accumulation of Al in the nuclei of brain cells.

Throughout this century, industrialized society has seriously affected the ecology by introducing huge amounts of pollutants into the atmosphere as well as marine and soil environments. On the other hand, it is known that these pollutants, in excess of certain levels of concentration, not only put at risk the life of living beings but may also cause the extinction of some species. It is therefore of basic importance to substantially increase quantitative determinations of trace element concentrations in biological specimens in order to assess the effects of pollutants. It is in this field that PIXE plays a key role in these studies, where its unique analytical properties are decisive. Moreover, since the importance of these research has been recognized in many countries, many scientists have been encouraged to continue or initiate new research programmes aimed to solve the worldwide pollution problem. This document presents an overview of those papers reporting the application of PIXE analysis to biological samples during this last decade of the XX century and recounts the number of PIXE laboratories dedicating their efforts to find the clues of the biological effects of the presence of pollutants introduced in living beings. Sample preparation methods, different kinds of samples under study and the use of complementary analytical techniques are also ilustrated.

This communication is devoted to nature determination and quantification by PIXE of metals contained in proteins after their separation by PolyAcrylamide Gel Electrophoresis (PAGE). After the electrophoresis, the gel is dried and each track is scanned with a 2.5 MeV proton beam which triggers metal X-ray fluorescence and then, allows to determine the type of metals contained in an electrophoretic band. For quantitative determination of the amount of the metal contained inside the band, the characteristic X-ray peak area is compared with those obtained with polyacrylamide gels doped with the same metal. The normalization has been achieved by using RBS measurements on the gel itself.

The procedure presented seems to be a very useful multielementary method for the metal content analysis and for the determination of the metal amounts inside proteins after their separation by electrophoresis. Furthermore it allows to check if metals remain bound to proteins.

PIXE was adopted to analyze trace elements in otoliths of Japanese flounder to discriminate among several local fish stocks. The otoliths were removed from samples caught at five different sea areas along with the coast of the Sea of Japan: Akita, Ishikawa, Kyoto (2 stations), and Fukuoka. Besides calcium as main component, strontium, manganese, and zinc were detected. Especially Sr concentrations were different among 4 areas except between 2 stations in Kyoto. It suggested that the fish in the 2 stations in Kyoto were the same stock differed to the others.

Vascular cell adhesion molecule-1 (VCAM-1) is transiently expressed on vascular endothelial cells in response to cytokines. It plays a major role in the adhesion of leucocytes to the endothelium by interaction with its ligand VLA-4, a member of the β1 integrin family.

We measured the serum concentration of the soluble VCAM-1 (sVCAM-1) in 114 patients with acute myocardial infarction (AMI) and 37 normal controls by enzyme-linked immunoassay in comparison with trace element concentration. sVCAM-1 levels were markedly higher (mean ± SD=833.2 ± 328.9 ng/ml) in the sera of patients with AMI than in normal controls (mean ± SD= 549.5 ± 188.8 ng/ml, p<0.001). Using PIXE we also determined concentration of magnesium, manganese, iron, copper, zinc, selenium, and calcium in sera of 43 patients with AMI. There were no clear correlation between the sVCAM-1 concentration and the magnesium, manganese, copper, selenium, iron. But there were significant correlation between the sVCAM-1 concentration and the zinc, calcium (p<0.05).

During PIXE analyses of biomedical samples often great damage of the sample occurs. This damage is always combined with mass loss and strong alterations of the initial structure. The loss of mass can be explained by the loss of volatile elements, mainly the major elements Hydrogen, Carbon, Nitrogen, and Oxygen. This results in a charge dependency of the element contents and has to be corrected during the data reduction. Here we describe measurements of different samples that monitor the mass loss and the charge dependency of the trace element concentrations. A model was developed to give the correct concentrations after the PIXE analyses. Additionally first results of PIXE analyses of gum tissue are reported. They give direct hints for amalgam residues inside the tissue in pathologically altered areas.

Airborne lead has been considered for many years one of the main pollutants adversely affecting the health of human beings. Moreover, this problem becomes remarkably important in large urban areas such as Mexico City. In order to assess the influence of atmospheric airborne lead in a children population, a biological blood sampling was carried out from September 1992 to June 1993 taking 698 samples in children with ages ranging from a few weeks to thirteen years old. Lead contents in whole blood were determined using anode stripping voltammetry as analytical technique. At the same time, aerosol lead contents were determined by PIXE from samples taken twice a week (two samples per day) in a neighbour area. In 58 % of the samples, lead contents in blood was found over the maximum permissible level established by the Center for Disease Control (CDC) of the U.S.A. The biological sampling was correlated to levels of airborne lead as well as children age and date of sampling. General results of these comparisons are presented.

We have measured the elemental concentrations of soy sauce and its actual raw materials which are used in a certain soy sauce factory. In the present measurement, we measured de-fatted soybean, wheat and salt as raw materials and soy sauce and soy sauce waste as final products. Five kinds of elements, such as Mn, Fe, Cu. Zn and Br, were detected. We obtained elemental concentrations of them except for Mn in each materials. The measured elemental concentration in soy sauce agreed well each other with the calculated one within the experimental errors using the measured concentration in the raw mateials and their weight in actual producing process. Contrary to our expectation, it was found that wheat contributes to soy sauce bromine concentration dominantly in the present case.

Proton Induced X-ray Emission analysis was applied to measure the concentration of Fe, Cu and Zn in liver biopsy samples with Wilson’s disease. Due to the small size of sample and non-conductive character of the material absolute measurement was not possible, therefore the ratio of elements such as Cu/Fe and Zn/Fe were determined. The comparison of these values obtained from normal liver samples helps the physicians to determine the stage of disease.

Mineral trace element concentration of human saliva from healthy volunteers, were investigated by Proton-Induced X-ray Emission (PIXE) analysis. The specimens were bombarded with Proton beams of 2 MeV from a Van de Graaff accelerator at NRC . The object of this measurement was to find a normal range of trace element concentration for Iranian people.

To obtain background information to formulate strategy to keep lakes, marshes and bogs free from pollution. soil and peat were sampled and analyzed continually. Sample preparation, size segregation and chemical extraction with ultra-pure water. 0.2M (NH₄)₂C₂O₄. 1M CH₃COONH₄, 0.01M EDTA·2Na, 1N HCl and 6N HCl were undertaken prior to the normal PIXE target preparation. It was found that with present improved PIXE plus correct chemical extraction procedure. chemical informations about a variety of mud components are easily brought through the element concentrations especially Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn and Br. The tendency that irreversible absorption components are more abundant than EDTA·2Na extraction components was common for Mn, Ni, Cu, Zn and Fe, The ratios of Ni. Cu and Zn to Fe in a irreversible absorption component were the same in an EDTA·2Na extraction component. On the other hand, Mn/Fe ratios were deviated to an EDTA·2Na extraction component side.

It is not only important for maintenance and improvement of health, but also indispensable for diagnosis and remedy of diseases to make inquiries into the biological defence mechanisms. Yonezawa et al. came across an induction of yet unknown defence mechanism(s) in mice which acquired radioresistance two weeks after low dose X-irradiation with 0.5 Gy. The 30-day survival rate after midlethal X-irradiation of the mice significantly increased by the pre-irradiation, but contrary to the common knowledge on radiation protection, recovery of the blood cell counts of thrombocytes, leukocytes and erythrocytes were not stimulated by the pre-irradiation. This study was planned to find some keys to elucidate the mechanism for the acquired radioresistance. Metal ions are well known to be important for enzyme activities as well as for metabolisms. Eleven elements, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Se and Br were analysed in mice sera by PIXE.

To investigate the physical and chemical characteristics of atmospheric aerosols, aerosol particles were sampled with classifying into 13 size ranges between 0.01 and 30µm. Collected aerosol particles were separated into the soluble and insoluble components. The concentrations of 15 elements in both components were determined by a PIXE analysis using a 2.0MeV-proton beam.

The mass size distribution of each element was illustrated in three types: mono-modal distribution having only one peak in the fine or coarse fraction and the bimodal distribution having one peak each in fine and coarse fractions. The mass mean diameter of 15 elements ranged between 0.62µm of S and 3.15µm of Fe. More than 85% of atmospheric aerosols consists of the lighter elements such as C, N, O, H and Al. The soluble component was dominant in the smaller size range and the insoluble component in the larger size range. Si, Ti and especially Fe existed in high insoluble state. Conversely, Ca, Zn, Br and especially S and Cl were dissolved in water.

The need to establish the elemental concentration profile for a clean environment and for a healthy organism is emphasized. Through several examples it is shown how PIXE has gained importance in elemental analysis in the fields of Medicine, Biology and Environment. Studies have been done on cancerous tumors and other diseased tissues. Elemental concentrations of blood, hair, teeth and nails have been correlated to specific diseases and to environmental pollution. Also plants, algae, lichens and tree rings have been analyzed as bio-sensors. The PIXE routines in four laboratories in Latinamerica are described. Their main environmental applications are in atmospheric aerosols, tree rings, waste water and others.

Marine aerosol from the western Pacific were collected by two types of samplers during a cruise from Nanhai of China through the west of Philippines to the equatorial and to the north-eastern of Solomon Archipelago. Collected samples were analyzed by PIXE. The data gave aerosol characteristics over the western Pacific, including concentrations, enrichmens and mass size distributions of detected elements, and possible sources of these elements were specially researched. The result indicates that Al, Si and Fe were associated with soil particles; Cl, Br, K, Ca and S showed characteristics of the sea-salt origin; and Cu, Zn and Pb were due to pollution from long-range transport of continental aerosol. We have also made comparison with data obtained in earlier studies over other regions of the Pacific.

Using the 22” isochronous cyclotron at the University of Chile, we have performed PIXE analyses on a group of samples collected from trees of metropolitan parks in Santiago. Dendrochronology was performed on each sample, which was then sectioned for the PIXE and other analyses, neutron activation and electro-chemistry. Available samples are trunk sections or cores obtained by the use of a 4.0 mm stainless steel incremental corer. We took three cores from each tree with permission of the municipalities. For the PIXE we use infinitely thick targets, as wood slabs taken along the trunk radius, and thin targets obtained by acid digestion of wood pieces and deposition on Kapton foils. Self supporting thick targets were placed directly in the PIXE chamber in a position so as to allow the irradiation of a specific annual ring. Potassium and Calcium appear as the most abundant elements in wood Other elements such as S, Cu, Zn, As, Br and Pb were detected in amounts above the natural background in wood, and can be attributed to environmental contamination. The K/Ca ratios appear to be different for each species of tree, and seem to be related to the physico-chemical properties of wood. Preliminary results show important amounts of As and Cu (supposedly from mining origin) with increasing presence in the recent years. Pb and Zn (supposedly from vehicle origin) are also higher in recent years.

The hard tissues of cephalopod, namely statoliths were analyzed with PIXE for the Japanese common squid Todarodes pacificus of the Sea of Japan origin in order to examine the relationship between the amount of trace elements in statoliths and environmental temperature of the squid habitat. Calcium, iron, zinc. copper and strontium were detected in the statoliths. Negative relationship was observed between Sr concentration in statoliths and environmental temperature. On the contrary to Sr, Fe and Zn concentration in statoliths related positively with environmental temperature. These observations revealed that the statoliths would be a useful thermometer for reconstructing the environmental temperature of cephalopod habitat as seen in the hard tissues of other marine organisms.

It is demonstrated in this work, that PIXE is a good mass indicator for suspended particles in urban environments. Results are presented for several samplings performed in urban and other environments in Chile and other countries. Aerosols were collected on filters operated by a Stacked Filter Unit (SFU) in the range of particles < 15 µm (PM₁₅) and < 10 µm (PM₁₀), mainly the respirable fraction. For samplings performed in downtown Santiago, the sum of the concentrations of the elements detected by PIXE correlated well with the indices of respirable suspended particles (RSP) measured by gravimetry. There was no high correlation for other samplings, near a crushing plant and near mineral storage. On the average, the sum of the PIXE results for Santiago’s aerosols represents about the 15% of the total mass collected in the respirable fraction. A measurement of collection efficiency for the 0.4 µm Nuclepore filter was performed by means of PIXE and gravimetry. These results were η_PIXE=0.98 and η_balance=0.96, for the PIXE and the gravimetric method.

Atmospheric aerosol samples were collected using an 8-stage cascade impactor or an automatic time sequence step sampler at Mount Qomolangma and Beijing. Element concentrations were analyzed by particle induced x-ray emission (PIXE) technique. Then the data were analyzed by the absolute principal factor analysis (APFA) to evaluate the principal components and the percent variance explained by them. As a result, it shows that the PIXE analysis combing with statistical method can effectively resolve the aerosol components in urban area and distinguish between local and remote area aerosol components in the area far from the pollution sources.

Aerosol samples were collected by using a 8 or 10-stage cascade impactor and a streaker sampler in Beijing area during the period from 1986 to 1991. Elemental analysis of each particle size fraction of the samples collected was carried out by particle induced X-ray emission (PIXE) at a 2×1.7 MV tandem accelerator. From the measured results of the concentrations for the 18 elements we obain the average value of the mass concentrations (total sum of these elemental concentrations) of the aerosol to be 42 mg/m³ in urban districts of Beijing and some characteristics of the aerosol in Beijing are also discussed.

Application of PiXE On biology, medicine and environment has been successful in the last twenty years. However, with the development of science and technique, lower detectable limit, sub-ppm sensitivity, more accurate quantitative analysis and the element chemical state information were presented which can not be achieved by PIXE. The synchrotron radiation as an excitation source to induce X-ray emission (SXRF) is a very powerful method with all the above requirements. In this paper the advantages of SXRF were discussed and compared with PIXE. The article shows our work on biological field by PIXE and SXRF also.

Trace element analysis via X-Ray Fluorescence (XRF) and Proton-Induced X-Ray Emission (PIXE) techniques were applied to several samples of fresh and processed foods. Thin samples of fresh fruits and vegetables, processed dry foods. and spices were included in these analyses. The results indicate that XRF and/or PIXE analysis is applicable to these types of samples but require special and simple modifications in sample preparation techniques, and the inclusion of new matrix type corrections for data analysis. However, the non-destructive nature, reproducibility, efficiency and high sensitivity that characterize these multi-element analytical procedures can provide new potential methods for detecting trace elements in foods and in many agricultural commodities. Toxic metals such as Hg, Pb. and As were detected in some foods. In addition, other essential or neutral trace elements such as Na, K, Mg, Ca, Cu, Cr, V, Zn, Mo, Fe, Mn, Ni, Se, Cl, S, and P were also detected. These and other elements can be analyzed rapidly and with high sensitivity for applications in process control and for certification of food quality. Developing these techniques and procedures specifically for food and for various agricultural products may provide new analytical options and help mitigate the expected impact of forthcoming regulations intended to establish limits and tolerance levels for micro toxicants and other essential nutrients in foods and agricultural products.

PIXE technique was applied to measurement of trace elements in total diet samples collected in Japan for estimation of their daily dietary intake. Results of PIXE analysis were compared with INAA Concentration of Cl, K, Mn and Zn by PIXE analysis well agreed with the results from NAA, while Ca, Fe and Cu showed different results between these two techniques. Preliminary data of elemental concentrations in Mate-cha, a kind of tea popular in South America, determined by ICP-AES indicated a little higher concentration of Cu than that by PIXE and much lower value than that by INAA For Zn. concentrations by PIXE and ICP well agreed to each other, while INAA gave much lower value. Japanese internal radiation doses by ¹³⁷Cs and ⁹⁰Sr were estimated to be 2.30µSv/year and 1.27µSv/year respectively as the effective dose equivalents using the daily intake data obtained for K and Ca.

A quantitative analysis method of the trace elements in biological specimens using the synchrotron radiation microprobe is described. The synchrotron radiation X-ray fluorescence microprobe system is calibrated by the standard sample specially prepared for the microprobe analysis. The mass thickness of each measured point is determined by measuring Compton scattering intensity in 17–20 keV from the sample. In this way, concentration of the trace elements in samples can be measured correctly. The measured values of the biological standard reference material NBS-SRM-1577a are in good agreement with the certified values. The longitudinal concentration variations of some trace element in a single hair of pregnant women have been measured by this method

The micro-SXRF scanning technique (size 150×150µm²) has been used to obtain the positional distributions of Zn, Cu, Fe, Mn, Br, Rb, K, Ca, Cl, S and Pt in cryo-section of the kidneys of normal mice treated with the anti-cancer drug cisplatin. The effect of cisplatin on element correlation was assayed by multivariate statistical analysis. The results of these examination imply that the elements affected by the cisplatin treatment are Zn and Fe.

A micro-scanning technique of SXRF (Synchrotron Radiation X-ray fluorescence) combined with multivariate statistical analysis was employed. The elements positional distribution in the kidney tissues of tree groups of Wistar rats (1, normal; 2, treated by CdCl₂; 3, Cd exposed rats treated with new complex) were obtained. The results show that Cd mainly distribute in the renal cortex of rat treated by CdCl₂. The level of Cd in the renal medulla is very low or not detectable. The elements measured in renal cortex of normal rat can be classified into two groups, Cu, Zn, Mn and Se belong to the same group. In acute CdCl₂ poisoning, Cd and Se have a very strong correlation, and the classification is different from normal renal cortex. After administration of a new chelator, Zn and Se have a very strong co-location and correlation, the classification of elements tend to return to normal distribution.

Synchrotron radiation microprobe XRF analysis has been used in the multielements analysis of human gastric cancer tissues. Elements of P, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, Se, Br and Rb were detected. The relative concentrations of P and K in cancer are higher than in normal tissue, but it is contrary for Cl, Ca, Se and Br.

By using position-sensitive spectrometer the rare-earth-element sample could be analyzed conveniently. This method of measurement was described and some of its features were discussed in this paper.