Katsumi Saitoh

METHOD OF QUANTITATIVE ANALYSIS MAKING USE OF BROMINE IN A NUCLEPORE FILTER

Nuclepore filters have been widely used for collecting atmospheric aerosols and such samples are quite convenient for PIXE since they can be analyzed without any treatment. However, some special methods, (which is somewhat different from existing standard methods for general samples), must be applied in order to perform quantitative analysis. We have developed a method of quantitative analysis for all elements making use of bromine, which is almost uniformly contained in general Nuclepore filters, as an internal standard. Then, for quantitative analysis of light elements, the standard-free method, which makes use of total yield of continuous x-rays, has been applied and it is found that this method can be successfully applied to practical aerosol samples. Moreover, the method was applied to bio-samples prepared by cutting frozen samples with a microtome, and the result is almost satisfactory. It is found that the present method can be successfully applied to any sample which can be made uniform.

EXAMINATION OF QUANTITATIVE ACCURACY OF PIXE ANALYSIS FOR ATMOSPHERIC AEROSOL PARTICLE SAMPLES: PIXE ANALYSIS OF NIST AIR PARTICULATE ON FILTER MEDIA

In order to confirm accuracy of the direct analysis of filter samples containing atmospheric aerosol particles collected on a polycarbonate membrane filter by PIXE, we carried out PIXE analysis on a National Institute of Standards and Technology (NIST, USA) air particulate on filter media (SRM 2783). For 16 elements with NIST certified values determined by PIXE analysis — Na, Mg, Al, Si, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn and Pb — quantitative values were 80–110% relative to NIST certified values except for Na, Al, Si and Ni. Quantitative values of Na, Al and Si were 140–170% relative to NIST certified values, which were all high, and Ni was 64%. One possible reason why the quantitative values of Na, Al and Si were higher than the NIST certified values could be the difference in the X-ray spectrum analysis method used.

PIXE ANALYSIS OF NIST URBAN PARTICULATE MATTER COLLECTED ON A POLYCARBONATE MEMBRANE FILTER

In order to confirm the accuracy of direct analysis of filter samples containing atmospheric aerosol particles collected on a polycarbonate membrane filter by PIXE, we carried out PIXE analysis on a polycarbonate membrane filter (Nuclepore®, pore size: 0.8 μm) on which was collected National Institute of Standards and Technology (NIST, USA) urban particulate matter (SRM 1648). We also investigated whether a polycarbonate membrane filter would possibly bias elemental quality determined by PIXE analysis. We found that the polycarbonate membrane filter did not bias values determined by PIXE. In the case of filter sample A in which the powder sample (urban particulate matter mixed with palladium-carbon powder (5% Pd)) was collected under dry conditions, elemental quantitative values were 80–110% relative to NIST certified and non-certified values except for Mn and Fe. On the other hand, in the case of filter sample B in which the powder sample was collected under wet conditions, elemental quantitative values were 70–110% relative to NIST certified and non-certified values except for Cl and Zn. Determined values for Mn and Fe in the case of filter sample A and Cl and Zn in the case of filter sample B were clearly lower than NIST certified and/or non-certified values, but this is believed to be attributable to the sampling procedure rather than a problem associated with PIXE analysis. Direct analysis of a filter sample containing aerosol particles by PIXE provided sufficient elemental quantity accuracy.

Loss of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and coplanar polychlorinated biphenyls during nitrogen gas blowdown process for ultra-trace analysis

This study examined standard solutions to assess the influence of the gas flow rate and organic solvent type on losses caused by gas blowdown of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and coplanar polychlorinated biphenyls (Co-PCBs). Results obtained here will contribute to maintaining analytical method performance and system quality for PCDD/DFs and Co-PCBs analyses. An organic solvent (with 0.5ml each of acetone, dichloromethane, n-hexane, and toluene), PCDD/DFs or Co-PCBs, and their 13C12-labeled compounds were put separately into 10ml pear-shaped flasks. The samples were blown to dryness at room temperature until the last trace of solvent disappeared. They were subsequently reconstituted in those flasks. Analyte recoveries were calculated by comparing blown samples to those that had not been blown. Recoveries of Co-PCBs were more affected than those of PCDD/DFs when the gas flow rates were set at 203, 261, 332, and 456ml/min. Losses of Co-PCBs were least at 203-332ml/min. Regarding losses of PCDD/DFs and Co-PCBs, the toluene solution showed the least variation in recovery. An actual soil sample extract was also examined using optimized conditions for the gas flow rate and solvent types obtained by experiments in standard solutions. Thereby, the blowdown conditions gave quantitative recoveries of 13C12-labeled compounds in the sample extract.

ATTEMPT AT IN-AIR PIXE ANALYSIS OF SPOT SAMPLES ON A FILTER-TAPE MOUNTED IN AN AUTOMATED BETA-RAY ABSORPTION MASS MONITOR

We attempted in-air-PIXE analysis of SPM using spot samples on a filter-tape mounted in an automated beta-ray absorption mass monitor. Al, Si, S, Fe and Zn, etc., which are of interest for identifying the behavior and characteristics of SPM, were detected on the SPM spot samples on a glass-fiber filter-tape, but the peaks of these elements were nearly identical to those of blank glass-fiber filter-tape. As such, it was difficult to detect elements present in SPM from the X-ray spectra of the spot samples. On the other hand, in the case of a PTFE membrane filter-tape, the S peak was distinct and the Fe peak was also clear, and peaks for elements Al, Mn and Zn, etc., were also confirmed. Consequently, if a method for determining quantity is established, direct multi-elemental analysis by in-air-PIXE of high time-resolution SPM spot samples collected on a PTFE membrane filter-tape mounted in a SPM monitor will be possible.

CHARACTERIZATION OF INSOLUBLE COMPONENTS IN FRESH SURFACE SNOW ON MOUNTAINS IN JAPAN

Fresh surface snow samples were collected at the summit or near the summit (700 - 1500 m altitude) of five mountains in Akita Pref., Japan. The elemental composition and particle shape of insoluble material in these snow samples was determined and/or observed by Particle Induced X-ray Emission (PIXE), a Scanning Electron Microscope (SEM) combined with Energy Dispersive X-ray (EDX) analysis. 21 kinds of elements for each mountain snow sample were determined by PIXE. Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti and Fe were the major components in each of the mountain snow samples, and those in relative abundance were almost the same in each case. With the aid of SEM and EDX analysis, silicon-rich small sphere (spherule) particles and aggregates of car exhaust particles were observed in every mountain snow sample. These results are represented as insoluble components of clouds and provide important knowledge for the source and mechanism of snowfall and rainfall at the ground level.

PIXE ANALYSIS OF SPOT SAMPLES ON NEW TYPE OF PTFE ULTRA-MEMBRANE FILTER-TAPE MOUNTED IN AN AUTOMATED BETA-RAY ABSORPTION MASS MONITOR

In order to obtain high time-resolution, i.e., chemical data of atmospheric particulate matter (PM) at one-hour intervals, we carried out direct analysis of suspended particulate matter (SPM) on hourly spot samples on a new type of PTFE ultra-membrane filter-tape mounted in an automated beta-ray absorption mass monitor by conventional PIXE. Analysis of hourly SPM spot samples revealed 20 elements (Na, Mg, Al, Si, S, Cl, K, Ca, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Sr and Pb) in total. Therefore, we are convinced that the chemical information that is obtained from high time-resolution PM spot samples on a PTFE membrane filter-tape mounted in an automated beta-ray absorption mass monitor will lead to new developments in PM research. Furthermore, elemental data obtained by the high time-resolution along with data for ionic species compositions, and SO2, NOX and other gaseous air pollutants at the same level, will make possible the analysis of detailed air pollution phenomenon.

APPLICATION OF MICRO-PIXE IN ATMOSPHERIC ENVIRONMENTAL SCIENCE RESEARCH: ELEMENTAL MAP OF LEAVES

Micro-beam scanning PIXE and scanning transmission ion microscopy (STIM) were applied to measurement of Siebolds beech (Fagus crenata Blume) leaves. The beech leaf samples were collected from selected beech trees at Tsugaru Pass near the Shirakami-Sanchi World Heritage Area, in the 1999 growing season. We focused our interest on the influence of the atmospheric environment (acidic deposition, aerosol and gaseous substances, etc.) on the forest ecosystem. Our approach to real images of the deposition of airborne particulate on leaves led to the elucidation of the process of elemental absorption from air and plant metabolism. As a result, it is suggested that 1) overlapping STIM images and elemental maps demonstrate the patterns of the elemental absorption into plants, 2) comparison of the elemental maps of leaves taken at the different growth stages may provide useful clues to the elemental accumulation mechanism in leaves, and 3) silicon distribution in leaves is indicative of airborne particulate deposition on them.

ELEMENTAL ANALYSIS OF ATMOSPHERIC PARTICLES COLLECTED ON POLYTETRAFLUOROETYLENE (PTFE) FILTER USING IN-AIR HELIUM ION INDUCED X-RAY EMISSION METHOD

In order to confirm the availability of an in-air Helium ion induced X-ray emission method for multi-elemental analysis of polytetrafluoroetylene (PTFE) filter sample containing atmospheric particles, NIST urban particulate matter (SRM 1648) collected on PTFE filter using a special small chamber was analyzed by an in-air PIXE method with Helium ions and a proton beam. In addition, we analyzed 10 elements, mixing a standard solution with different concentrations to confirm detection sensitivity of characteristic X-ray peaks. As a result, it is suggested that 1) elements that are lighter than Zn and Pb can be satisfactorily measured using the in-air Helium ion induced X-ray emission method if the amount contained in the filter sample is at least 0.1 mg/L, i.e., 15 ng/cm2, 2) the in-air Helium ion induced X-ray emission method is useful as a method for quantitatively analyzing the light elements such as Mg, Al, Si, S and Cl that are important for identifying the behavior and characteristics of atmospheric particles from the PTFE filter sample containing atmospheric particles, and 3) in the case of the PTFE filter sample containing atmospheric particles, it is possible to measure elements from Mg to Pb by means of analysis using Helium ions and protons.

PRESUMED CAUSE OF MASS DEATHS OF ROOKS (CORVUS FRUGILEGUS PASTINATOR) USING PIXE ANALYSIS

Eighty-nine wild birds were found dead in Ogata Village in northern Japan in March 2006. Eighty-eight of the birds were rooks (Corvus Frugilegus Pastinator), which are migratory birds. Since the use of rodenticide (thallium sulfide and zinc phosphide) in the area around where the birds had been found was revealed by a survey, etiological and pathological examinations including elemental analysis by means of particle induced X-ray emission (PIXE) were conducted. Elemental analysis showed high concentrations (56–365 dry-μg/g) of thallium in the lungs, gastric contents, intestines, livers and kidneys. Histopathological examination revealed vacuolar degeneration of hepatic cells and granular and/or hyaline droplet degeneration of renal tubular epithelia. The results suggest that the mass deaths were caused by thallium poisoning.