An application of INAA and PIXE on the analysis of nutritional and toxicological elements in samples of drinkable water

Multielemental detection using Instrumental Neutron Activation Analysis (INAA) and Proton-Induced X-Ray Emission (PIXE) of drinkable water of Florence (Italy) is described. The concentrations of 52 elements were measured. No chemical treatment was performed on the samples, before or after irradiation. On the basis of an appropriate combination of the two analytical techniques, a procedure for aluminum determination was developed. Results are briefly discussed from a methodological point of view.     

Measurement of PM 10/2.5 fractionated respirable particles in Urban Toronto by INAA,PIXE, ICP-AES,and LAMS

The chemical analysis of urban Toronto airborne particulate matter (PM), size segregated into respirable PM10/2.5, is presented. The characterization of PM by use of proton-induced X-ray emission analysis (PIXE), and inductively coupled plasma-atomic emission spectrometry revealed elemental information; a newer laser ablationionization mass spectrometry approach has the potential to expand the chemical information from PM by analyzing both the inorganic and organic species. These PM analytical approaches will be continued in the future for studying (1) emission source identification, (2) inhalation health hazards, and (3) urban smog chemistry.     

Applications of PIXE in the life sciences

Biological Trace Element Research - During the last decade, particle-induced X-ray emission spectrometry (PIXE) has been accepted by the analytical chemistry community as a standard method. Instead...     

Matrix effects in PIXE analysis of aerosols and ashes

A comparison of instrumental neutron activation analysis (INAA) and proton-induced X-ray emission (PIXE) results for sizefractionated atmospheric aerosols (“coarse” and “fine” fractions with an equivalent aerodynamic diameter of 2–10 Μm and < 2 Μm, respectively, or the PM10 fraction) showed that PIXE yielded significantly lower results for the PM10 and coarse fractions, especially for elements with a low Z resulting from a particle size effect. Somewhat lower PIXE results were also obtained for the fine fraction of atmospheric aerosols. A correction is also needed for irregularly shaped deposits of combustion aerosols collected by a cascade impactor in 11 size fractions ranging from 0.016 to 14.3 Μm, as well as for thick samples of fly and bottom ashes. An equivalent layer thickness (ELT) model is proposed to correct the matrix effects in PIXE. The approaches for the calculation of ELT using a comparison of PIXE and INAA results or by comparing PIXE results obtained using two different incident proton beam energies (1.31 and 2.35 MeV) are described. The correction for the ash pellets and irregular deposits are also discussed.     

INAA of trace elements in colorectal cancer patients

The concentration of trace elements in samples of both colorectal cancer tumors and normal tissues of a Mexican population were irradiated for 30 s and 4 h and their elemental content were measured by instrumental neutron activation analysis. Ca, Cu, Co, I, Mg, Se, Fe, Zn, Hg, Ba, and Cr were analyzed. Alterations in Co, Fe, I, and Ba were found in tumors with respect to normal tissues.     

PIXE technique for calcium analysis of human bone

The determination of calcium content in human bone tissue is very useful in metabolic diseases of bone, such as renal osteodystrophy, osteoporosis, hyperparathyroidism, and osteomalacia of diverse etiology. The PIXE technique allows calcium to be directly determined in bioptic tissue sections properly, sampled for histological optical and/or electron microscopy examination. Bone semithin sections (3 μm thick, 4×4 mm² dimensions), cut by ultramicrotome and deposited onto polyvinyl acetate films, underwent PIXE analysis using the CISE set-up. Histomorphometric (after standard staining), evaluation of calcified bone volume (CBV) in absolute value allows calcium density to be determined. A total of nine bone biopsies were analyzed (three sections each) obtaining values ranging between 352 and 482, with an average value of 421.5±15.3 (M±SE) μg/μL, in good agreement with literature data (obtained by AAS technique on dissected bone samples). The aim of this paper is to emphasize the usefulness, of combined PIXE and histomorphometric techniques for the study of calcium content in bone tissue in both healthy and diseased bones.     

Trace elemental analysis of cancer-afflicted intestine by PIXE technique

Trace elemental analysis was carried out in the biological samples of cancer-afflicted intestine using the particle-induced X-ray emission technique (PIXE). A 2-MeV proton beam was employed to excite the samples. From the present results, it can be seen that the concentration of the elements Cr, Fe, and Ni are higher in the cancerous tissue of the intestine than those observed in the normal tissue, whereas the concentration levels of the element Zn is slightly lower in the cancer tissue of intestine than that observed in the normal tissue. The concentrations of S, Cl, K, Ca, Ti, Mn, Co, and Cu in the cancer tissue of the intestine are in agreement with those observed in the normal tissues within standard deviations. The present results support the previous observations that Ni and Cr are carcinogenic agents. The observed slightly low levels of zinc in the cancer tissue of the intestine suggest that zinc could possibly inhibit the tumor growth and development of neoplastic transformation. For correctly assessing the role played by the trace elements in initiating, promoting, or inhibiting cancer in various organs, there is a need for the acquisition of more data by trace elemental analysis from several investigations of this type undertaken in different regions.     

Analysis of membrane filters and thick fly ash samples by PIXE

Biological Trace Element Research - The possibility of the routine PIXE measurement of environmental samples has been tested at the INP in ?e?. Both thin samples of aerosols collected on...     

Surface Sampling of Spores in Dry-Deposition Aerosols

The ability to reliably and reproducibly sample surfaces contaminated with a biological agent is a critical step in measuring the extent of contamination and determining if decontamination steps have been successful. The recovery operations following the 2001 attacks with Bacillus anthracis spores were complicated by the fact that no standard sample collection format or decontamination procedures were established. Recovery efficiencies traditionally have been calculated based upon biological agents which were applied to test surfaces in a liquid format and then allowed to dry prior to sampling tests, which may not be best suited for a real-world event with aerosolized biological agents. In order to ascertain if differences existed between air-dried liquid deposition and biological spores which were allowed to settle on a surface in a dried format, a study was undertaken to determine if differences existed in surface sampling recovery efficiencies for four representative surfaces. Studies were then undertaken to compare sampling efficiencies between liquid spore deposition and aerosolized spores which were allowed to gradually settle under gravity on four different test coupon types. Tests with both types of deposition compared efficiencies of four unique swabbing materials applied to four surfaces with various surface properties. Our studies demonstrate that recovery of liquid-deposited spores differs significantly from recovery of dry aerosol-deposited spores in most instances. Whether the recovery of liquid-deposited spores is overexaggerated or underrepresented with respect to that of aerosol-deposited spores depends upon the surface material being tested.     

Review and Latest Results of Laboratory Investigations of Titan's Aerosols

Titan, the largest satellite of Saturn, has an atmosphere chiefly made up of N₂ and CH₄, and including many organics. This atmosphere also partly consists of hazes and aerosol particles which shroud the surface of this satellite, giving it a reddish appearance. The aerosols observed in Titan's atmosphere are thought to be synthesized at high altitudes (>300 km) and fall to the surface. Varying with temperature profiles, condensation phenomena take place in the lower atmosphere, about 100 km below. These solid particles, often called tholins, have been currently investigated for many years by laboratory scientists and physics modellers. This paper assesses past research and results in different fields (elemental composition, optical constants, pyrolysis, particle size), highlighting interests and questions aroused by these studies. It also presents the latest results and advances, and concludes with existing problems and future pathways.     

Aerosols transmit prions to immunocompetent and immunodeficient mice

Prions, the agents causing transmissible spongiform encephalopathies, colonize the brain of hosts after oral, parenteral, intralingual, or even transdermal uptake. However, prions are not generally considered to be airborne. Here we report that inbred and crossbred wild-type mice, as well as tga20 transgenic mice overexpressing PrP(C), efficiently develop scrapie upon exposure to aerosolized prions. NSE-PrP transgenic mice, which express PrP(C) selectively in neurons, were also susceptible to airborne prions. Aerogenic infection occurred also in mice lacking B- and T-lymphocytes, NK-cells, follicular dendritic cells or complement components. Brains of diseased mice contained PrP(Sc) and transmitted scrapie when inoculated into further mice. We conclude that aerogenic exposure to prions is very efficacious and can lead to direct invasion of neural pathways without an obligatory replicative phase in lymphoid organs. This previously unappreciated risk for airborne prion transmission may warrant re-thinking on prion biosafety guidelines in research and diagnostic laboratories.     

Enhanced sensitivity for the determination of selenium by INAA

A working analytical procedure for selenium determinations by INAA, using γ spectrometry with a germanium well-type detector, is presented. The spectral line at 400.7 keV is employed, enhanced with the effect of energy summing in true coincidence of cascade photons. The main advantage of the method is high efficiency and reliable, interference-free results; potential drawbacks are increases in input count rate and pile-up losses, decrease in resolution, and sensitivity to errors in sample-to-detector geometry. The procedure is applied to certification analysis of reference materials, large-area biomonitoring by oak leave samples, and determination of separated proteins.     

Determination of sodium-to-calcium ratio in mouse femora by INAA

Biological Trace Element Research - Within the scope of the study of the heteroionic exchange in the bone mineral, the sodium-to-calcium ratio was established in femora of 55 male ICR mice. The...     

PCR和Southern Blot检测土拉弗氏菌气溶胶

为提高检测土拉弗氏菌的特异性和敏感性,建立了土拉菌ＰＣＲ及核酸杂交检测方法。运用平板计数、多聚酶链反应对土拉菌气溶胶稳定性进行了比较,结果表明ＰＣＲ具有较高灵敏度,并且在采样后３小时ＰＣＲ就可以得出定性结果,而平板计数则需要３～７天。采用ＰＣＲ法合成了土拉菌３７６－ｂｐ探针,分别对细菌菌液、５６８－ｂｐＰＣＲ产物和气溶胶样品进行杂交,结果表明菌悬液直接杂交可检出１０５ＣＦＵ左右的细菌,检测ＰＣＲ产物可达４０ｐｇ。ＰＣＲ和Ｓｏｕｔｈｅｒｎ印迹相结合有利于细菌的分离鉴定     

Hint of polar distribution in calcium channels under PIXE analysis

Pollen tubes ofLilium longiflorum were treated for 10–30 min with 10⁻⁵ M CoCl₂, which binds to calcium channels in the plasma membrane and blocks them. Cobalt analyses were performed with the Heidelberg proton microprobe, using 3 MeV protons, a beam current of about 200 pA, and a spot size of 3×5 μm². X-ray spectra revealed that coblat has much higher concentrations in the cell than in the surrounding dried medium. The line scans, taken along the longitudinal cell axis in 1-μm steps, showed a cobalt gradient similar to the calcium gradient of the same cell. Based on our findings, we can conclude that neither do the cobalt signals come from the cell wall nor is the cobalt exclusively bound to the intracellular calcium-binding sites. There-fore, the present results suggest a polar distribution in calcium channels in the plasma membrane of pollen tubes.     

Direct Assessment of Viral Aerosols on Cell Cultures

A technique is described for the direct exposure of cell cultures to airborne virus enabling quantitation of the virus in concentrations as low as one plaque-forming unit per liter of air.     

Feasibility of Breast Cancer Screening by PIXE Analysis of Hair

To reveal the role of key elements present in the hair of breast cancer patients on cancer development, the levels of a number of elements in scalp hair samples of 82 people including healthy individuals, people suffering from benign breast disease, and breast cancer patients were measured by PIXE analysis. Pellets of hair samples were prepared and bombarded by 2.2 MeV proton beam of a 3-MV Van de Graaff accelerator. The number of incident ions hitting the sample was indirectly measured using the RBS spectrum of a thin Ag film placed in the beam path. The concentrations of S, Cl, K, Ca, Fe, and Cu in the hair of healthy individuals were in agreement with those observed in the hair of hyperplasia and cancer patients within standard deviations. However, a lower average level of zinc was found in samples from hyperplasia and breast cancer patients. Strong positive correlations were found between iron and potassium as well as between calcium and potassium in the cancer patients. These results could be of significance in the screening for breast cancer.