<Superscript>239, 240, 241</Superscript>Pu fingerprinting of plutonium in western US soils using ICPMS: solution and laser ablation measurements

Sector field inductively coupled plasma mass spectrometry (SF-ICPMS) has been used with analysis of solution samples and laser ablation (LA) of electrodeposited alpha sources to characterize plutonium activities and atom ratios prevalent in the western USA. A large set of surface soils and attic dusts were previously collected from many locations in the states of Nevada, Utah, Arizona, and Colorado; specific samples were analyzed herein to characterize the relative contributions of stratospheric fallout vs. Nevada Test Site (NTS) plutonium. This study illustrates two different ICPMS-based analytical strategies that are successful in fingerprinting Pu in environmental soils and dusts. Two specific datasets have been generated: (1) soils are leached with HNO₃-HCl, converted into electrodeposited alpha sources, counted by alpha spectrometry, then re-analyzed using laser ablation SF-ICPMS; (2) samples are completely dissolved by treatment with HNO₃-HF-H₃BO₃, Pu fractions are prepared by extraction chromatography, and analyzed by SF-ICPMS. Optimal laser ablation and ICPMS conditions were determined for the re-analysis of archived alpha spectrometry “planchette” sources. The best ablation results were obtained using a large spot size (200 μm), a defocused beam, full repetition rate (20 Hz) and scan rate (200 μm s⁻¹); LA-ICPMS data were collected with a rapid electrostatic sector scanning experiment. Less than 10% of the electroplated surface area is consumed in the LA-ICPMS analysis, which would allow for multiple re-analyses. Excellent agreement was found between ^239+240Pu activities determined by LA-ICPMS vs. activity results obtained by alpha spectrometry for the same samples ten years earlier. LA-ICPMS atom ratios for ²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu range from 0.038–0.132 and 0.00034–0.00168, respectively, and plot along a two-component mixing line (²⁴¹Pu/²³⁹Pu = 0.013 [²⁴⁰Pu/²³⁹Pu] – 0.0001; r ² = 0.971) with NTS and global fallout end-members. A rapid total dissolution procedure, followed by extraction chromatography and SF-ICPMS solution Pu analysis, generates excellent agreement with certified ^239+240Pu activities for standard reference materials NIST 4350b, NIST 4353, NIST 4357, and IAEA 385. ^239+240Pu activities and atom ratios determined by total dissolution reveal isotopic information in agreement with the LA-ICPMS dataset regarding the ubiquitous mixing of NTS and stratospheric fallout Pu sources in the regional environment. For several specific samples, the total dissolution method reveals that Pu is incompletely recovered by simpler HNO₃-HCl leaching procedures, since some of the Pu originating from the NTS is contained in refractory siliceous particles.     

Evaluation of measurements of 238Pu, 239Pu and 240Pu in urine at the microbecquerel level using thermal ionization mass spectrometry and alpha-spectrometry at Los Alamos National Laboratory: Results of a two year comparison test (LA-UR-06-8055)

The Intercomparison Studies Program (ISP) at the Oak Ridge National Laboratory (ORNL, Oak Ridge, TN, USA) provides natural-matrix urine quality-assurance/quality-control (QA/QC) samples to radiobioassay analysis laboratories. In 2003, a single laboratory (Los Alamos National Laboratory LANL, Los Alamos NM USA) requested a change in the test-samples provided previously by the ISP. The change was requested to evaluate measurement performance for analyses conducted using thermal-ionization mass spectrometry (TIMS). Radionuclides included ²³⁹Pu at two activity levels (75–150 μBq^·sample⁻¹ and 1200–1600 μBq^·sample⁻¹) and ²³⁸Pu (3700–7400 μBq^·sample⁻¹). In addition, ²⁴⁰Pu was added to the samples so that the ^239+240Pu specific activity was 3700–7400 μBq^·sample⁻¹. In this paper, the results of testing during the period May, 2003 through September, 2005 are presented and discussed.     

Comparison of alpha-spectrometry and alpha/gamma ratio method for the determination of americium in plutonium bearing fuel materials

Determination of americium is one of the requirements of chemical quality assurance of plutonium bearing fuel materials. Alpha-spectrometry is generally used for the determination of ²⁴¹Am in Pu bearing fuels since the efficiency of semiconductor detector used for alpha-spectrometry is independent of the alpha-particle energy in the 4 to 8 MeV range. However, this method has limitations for Pu samples containing extremely small or very large amounts of ²⁴¹Am. Thus an alternative methodology based on alpha/gamma (α/γ) activity ratio was developed and tested using different samples. The method is based on the determination of total γ-activity (of 60 keV peak) of an aliquot of the solution and the total α-activity present in the aliquot. The method is fast as it does not involve chemical separation of Pu and Am as required in the alpha-spectrometric method. Data obtained on synthetic and real life samples demonstrates the usefulness of the developed alpha/gamma ratio method for the determination of ²⁴¹Am in Pu bearing fuel samples.     

Determination of239,240Pu and241Am in environmental samples

An accurate and reliable method has been developed and routinely carried out for the sequential determination of^239,240Pu and²⁴¹Am in environmental samples. After suitable pretreatment.^239,240Pu and²⁴¹Am are separated from other elements by means of the anion exchange resin method. Americium-241 is purified by coprecipitation with calcium oxalate and then ion exchanged in mixed media of the mineral acid-methanol. In the analysis,²⁴²Pu (or²³⁶Pu) and²⁴⁴Cm are used as chemical yield monitors. The recoveries of the yield monitors in the analyses of some kinds of environmental samples were 7080% for plutonium and 7686% for curium. The concentration of^239,240Pu in the coastal sea water were 7.022 Bq/l and that of²⁴¹Am was 1.26.3 Bq/l. The mean concentrations of^239,240Pu in the edible parts of the marine products ranged from 0.22 to 7.4 mBq/kg · fresh and those of²⁴¹Am ranged from 0.11 to 2.6 mBq/kg · fresh.     

Geochemical studies on the Chernobyl radioactivity in environmental samples

Artificial radionuclides in deposition and airborne dust samples in 1986 were measured at Tsukuba and 11 stations in Japan. In May 1986, the Chernobyl radioactivity was observed in rain and air samples in Japan. The Chernobyl-derived Pu isotopes, which are characterized by higher²³⁸Pu/^239,240Pu (85) and²⁴¹Pu/²³⁸Pu (0.5) activity ratios than those of the nuclear test-derived Pu and⁹⁰Sr, were detected in deposition and airborne dust samples in Japan, as well as volatile radionuclides such as¹³¹I and¹³⁷Cs. However, the activities of Pu isotopes and⁹⁰Sr observed in Japan were about two and three orders of magnitude lower than those expected from the activity ratios in the total release at Chernobyl, which means that the residence time of Pu in the air was shorter than that of¹³⁷Cs. In order to understand the fractionation between the Chernobyl radionuclides we studied about individual wet and dry deposition. The results suggest that this cause is due to the difference of the particle size of radionuclide-bearing particles, which may be related to the release process of Chernobyl radionuclides.     

Determination of total and extractable hydrogen peroxide in organic and aqueous solutions of uranyl nitrate

The development of a spectrophotometric method for the determination of hydrogen peroxide in uranyl nitrate solutions is reported. The method involves the measurement of the absorbance at 520 nm of a vanadyl peroxide species. This species was formed by the addition of a reagent consisting of vanadium (V) (50 mmol·dm⁻³) in dilute sulphuric acid (2 mol·dm⁻³ H₂SO₄). This reagent, after dilution, was also used as an extractant for organic phase samples. The method is simple and robust and tolerant of nitric acid and U(VI). Specificity and accuracy were improved by the application of solid phase extraction techniques to remove entrained organic solvents and Pu(IV). Reverse phase solid phase extraction was used to clean-up aqueous samples or extracts which were contaminated with entrained solvent. A solid phase extraction system based upon an extraction chromatography system was used to remove Pu(IV). Detection limits of 26 μmol·dm⁻³ (0.88 μg·cm⁻³) or 7 μmol·dm⁻³ (0.24 μg·cm⁻³) for, respectively, a 1 and 4 cm path length cell were obtained. Precisions of RSD=1.4% and 19.5% were obtained at the extremes of the calibration curve (5 mmol·dm⁻³ and 50 μmol·dm⁻³ H₂O₂, 1 cm cell). The introduction of the extraction and clean-up stages had a negligible effect upon the precision of the determination. The stability of an organic phase sample was tested and no loss of analyte could be discerned over a period of at least 5 days. The presence of trace levels of reductants interfered with the determination, e.g., hydrazine (<2 mmol·dm⁻³), but this effect was ameliorated by increasing the concentration of the colormetric reagent.     

Solid Phase Extraction of Solanesol

The method of solid-phase extraction (SPE) for the concentration and clean-up of tobacco extract samples during solanesol analysis was proposed in this work. A column (200 mm × 4 mm i.d.) packed with 0.10 g silica gel (with particle size of 70 μm, porosity of 0.5 and surface area of 400 m² g⁻¹) was used as SPE cartridge. Several extraction parameters, such as sample loading flow (0.3–7 mL min⁻¹), sample volume (5–50 mL), the column adsorption capacity and elution were evaluated to provide a fast, quantitative and reproducible SPE method. A mean solanesol recovery was 97.5 ± 1.6% (mean ± sd) and mean intra- and inter-day reproducibility was higher than 97%. It can be used in the analysis of solanesol in tobacco extracts.     

Determination of isotopic composition and concentration of uranium,plutonium and neodymium by mass-spectrometric isotope dilution in the irradiated fuel of the Czechoslovak atomic power station A-1

Determination of the isotopic composition and concentration of uranium, plutonium and neodymium by mass-spectrometric isotope dilution is described. Isotopes²³³U,²⁴²Pu and¹⁵⁰Nd were used as spikes. Isotopic composition was measured with a Varian-TH 5 mass spectrometer. Optimum amounts loaded onto the filament were 2–5 μg U, ∼0.1 μg Pu and <0.1 μg Nd. The accuracy and reproducibility of the isotopic ratio and concentration measurements were evaluated.     

Simulatenous determination of uranium and plutonium in inactive purex process solution by X-ray fluorescence

By intensity measurements of the uranium and plutoniumL _α1-lines these elements can be determined simultaneously either in aqueous or in organic Purex process solutions. Thorium was used as an internal standard. The sensitivity of the method is about 10⁵ cpm/mg U, Pu/ml and the detection limits are around 2–3 μg U, Pu/ml. The analytical range extends from 0.003 mg U, Pu/ml up to 10 mg U, Pu/ml. A time-saving routine procedure is described. Interferences detected at extreme U/Pu concentration ratios are discussed and explained.     

Use of ultrathin zirconium phosphate layers for the preparation of alpha-spectrometric samples

Ultrathin zirconium phosphate layers about 300–600 nm in thickness have been prepared on stainless steel supports. The adherence and homogeneity of the layers are sufficient. The adsorption properies in respect to alpha-emitters (²³⁹Pu and²⁴¹Am) have been studied. The adsorption equilibrium is reached in half an hour and a total capacity of about 3–4 μg Pu has been estimated. Alpha-spectrometric properties of the samples have been evaluated by measuring the half-width of the²³⁹Pu main peak, which is close to the resolution ability of the detector.     

Measurement of 241Pu in Environmental Samples

Concentrations of ²⁴¹Pu in the air and deposition samples in Finland after the 1986 Chernobyl accident were estimated with the aid of ingrowth of ²⁴¹Am. Plutonium-241 was clearly shown to be present in the Chernobyl fallout in Finland. Pu was unevenly distributed and the mean radioactivity ratio of ²⁴¹/^239,240Pu was 70 for air and 71 for deposition samples. Here, a radiochemical method for determination of ²⁴¹Pu in the environmental samples was also developed. The method was based on the liquid scintillation measurement of ²⁴¹Pu with a pulse shape analyser after Pu separation. Efficiency calibration was performed with the aid of ³H standard instead of the ²⁴¹Pu standard. The method was tested by comparing the results with the method of ²⁴¹Am ingrowth and some reference samples. The detection limit for ²⁴¹Pu was 0.007 Bq per sample. The ²⁴¹Pu concentrations in the sediment samples taken from the Baltic Sea varied between <0.5 and 27 Bq·kg^-1. The effect of the Chernobyl accident could be seen both from the ²⁴¹Pu concentrations and from the Pu isotope ratios in vertical distributions of sliced samples.     

Determination of cisapride in human plasma by high-performance liquid chromatography with fluorescence detection

Summary A new sensitive HPLC-FLD method has been developed and validated for the determination of cisapride in human plasma for a bioequivalence study. A gradient method was used to remove late-eluting plasma components of no interest. The separation was performed on a Li-ChroCART 250-4 Purospher RP-18 (5 μm particle) analytical column fitted with a LiChroCART 4-4 Purospher RP-18 endcapped (5 μm particle) guard column. The excitation and emission wavelengths were 295 and 350 nm during fluorescence detection. The calibration plot was linear in the range of 5–200 ng mL⁻¹. A demethoxy analogue of cisapride was used as internal standard.     

Sensitive determination of phloroglucinol in human plasma by liquid chromatography-tandem mass spectrometry

Summary A sensitive and selective liquid chromatographic method coupled with tandem mass spectrometry (LC-MS-MS) was developed for the quantification of phloroglucinol in human plasma. Resorcinol was used as internal standard, with plasma samples extracted using ethyl acetate. A centrifuged upper layer was then evaporated and reconstituted with mobile phase. The reconsituted samples were injected into a C₁₈ XTerra MS column (2.1×100 mm) with 3.5 μm particle size. The analytical column lasted for at least 500 injections. The mobile phase was 15% acetonitrile (pH 3.0), with a flow rate at 100 μL min¹. The mass spectrometer was operated in positive ion mode using electrospray ionization. Using MS-MS in multiple reaction monitoring (MRM) mode, phloroglucinol was detected without severe interferences from the plasma matrix. Phloroglucinol produced a parent molecule ([M+H]⁺) atm/z 127 and a corresponding product ion atm/z 8l. Detection of phloroglucinol in human plasma was accurate and precise, with quantification on limit at 0.5 ng mL¹. The method has been successfully applied to a study of phloroglucinol in human specimens.     

Simultaneous RP-LC Determination of Losartan Potassium, Ramipril, and Hydrochlorothiazide in Pharmaceutical Preparations

A simple, rapid, and precise reversed-phase high-performance liquid chromatographic method has been developed for simultaneous determination of losartan potassium, ramipril, and hydrochlorothiazide. The three drugs were separated on a 150 mm × 4.6 mm i.d., 5 μm particle, Cosmosil C₁₈ column. The mobile phase was 0.025 m sodium perchlorate–acetonitrile, 62:38 (v/v), containing 0.1% heptanesulphonic acid, pH adjusted to 2.85 with orthophosphoric acid, at a flow rate of 1.0 mL min⁻¹. UV detection was performed at 215 nm. The method was validated for linearity, accuracy, precision, and limit of quantitation. Linearity, accuracy, and precision were acceptable in the ranges 35–65 μg mL⁻¹ for losartan, 1.75–3.25 μg mL⁻¹ for ramipril, and 8.75–16.25 μg mL⁻¹ for hydrochlorothiazide.     

Evaluation of combustion characteristics of different size elbistan lignite by using TG/DTG and DTA

In this research, the relationship between particle size and combustion kinetics and combustion properties of lignite samples was examined by utilizing the thermogravimetric (TG/DTG) and differential thermal analysis (DTA) techniques. The lignite samples separated into different size fractions were subjected to non-isothermal thermogravimetric analysis between ambient and 900°C in the presence of 50 mL min⁻¹ air flow rate. Activation energy (E) and Arrhenius constant (A _r) of combustion reaction of each size was evaluated by applying Arrhenius kinetic model to the resulting data. Combustion properties of the samples were interpreted by careful examination of the curves. The apparent activation energies in major combustion region were calculated as 41.03 and 53.11 kJ mol⁻¹ for the largest size (−2360+2000 μm) and the finest size (−38 μm), respectively.     

Micro-beam scanning PIXE analysis system at the National Institute of Radiological Sciences (NIRS)

In 2000, micro-beam scanning particle induced X-ray emission (PIXE) analysis system was installed in NIRS. This system provides the ability of multi-elemental mapping on maximum 2.5 mm×2.5 mm area in a spatial resolution of about 1 μm with quadrupole triplet magnets and a scanning coil. The estimated beam size on good tuning was 0.40×0.65 μm², that is one of the best capacity of micro-beam scanning PIXE system in the world. The performance was tested using small biological samples such as fish scale, pollen and small fish eye. Fine elemental maps were obtained in the samples of about 30 μm to a few mm size in the special resolution of about 1 μm. This revised version was published online in August 2006 with corrections to the Cover Date.     

High performance liquid chromatography method for the determination of meropenem in human plasma

Summary This paper describes an HPLC method for the determination of meropenem in human plasma. The method uses solid phase extraction (SPE) of the samples and has good sensitivity, precision and accuracy. The limit of quantification in plasma samples is 0.02 μg mL⁻¹. Calibration curves were linear over a large dynamic range, namely within 0.02–50 μg mL⁻¹. The method was applied to the determination of meropenem levels in patients receiving meropenem, as a single dose or at steady state.     

Development of new methods for the analysis of carboxylic acids and carbonyl compounds in size classified raindrops by CE for application in modelling atmospheric processes

Summary At the present time the formation processes of clouds and precipitation are not totally understood. Because cloud- and raindroplets are major sinks for chemical species in the atmosphere it is important to understand the physical and the chemical processes which occur during precipitation. The development of models is hindered by the scarcity of information about the scavenging of gases or aerosol particles by raindrops of different sizes. These processes can only be investigated by field experiments using microanalytical methods and analysing single raindrops as well as size-classified raindrop samples. Raindrops were collected according to their size by freezing them in liquid nitrogen (“Guttalgor” method). Sample volumes of the smallest raindrop sizes (radius <200μm) were usually smaller than 2 μL. The analysis of microvolumina in the size range of μL down to pL required the development of methods designed especially for this purpose. Analysis of rain samples was carried out by capillary electrophoresis. Organic acids were determined using a new electrolyte system for indirect detection. With this system it was possible to determine monocarboxylic acids (C₁−C₄) dicarboxylic acids (C₂−C₄, C₉) and inorganic anions (Cl⁻, NO₃ ⁻, SO₄ ²⁻) in the rain samples. Carbonyl compounds were analysed after derivatisation with dansylhydrazine using direct UV-detection. The system allows the identification of aliphatic carbonyl compounds (C₁−C₃, C₅) as well as benzaldehyde. It was found that carbonyl compounds and carboxylic acids showed concentration maxima at different raindrop radii. These concentration maxima are a consequence of particle scavenging. By using the results of a former experiment we concluded that the two species are located on different aerosol particle sizes. Reasons for the different particle sizes where these species are located are discussed. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996     

Determination of the <Superscript>240</Superscript>Pu/<Superscript>239</Superscript>Pu atom ratio in global fallout at two locations in the Northern Hemisphere

Summary Extensive soil and sediment sampling was conducted along the Colorado Front Range and the plains east of the Front Range at locations believed to only be exposed to global fallout. The average ²⁴⁰Pu/²³⁹Pu atom ratio in the samples collected in Colorado was determined to be 0.165±0.008. A limited number of samples were collected at various locations in the Arctic at approximately 70° N latitude. Analyses of these samples predict that the ²⁴⁰Pu/²³⁹Pu atom ratio in environmental samples collected at 70° N latitude at locations only containing fallout is 0.183±0.009. These results provide data that help to precisely define the ²⁴⁰Pu/²³⁹Pu atom ratios representative of global fallout at the two locations studied.     

Effect of particle size on pyrolysis characteristics of Elbistan lignite

In this study, the relationship between particle size and pyrolysis characteristics of Elbistan lignite was examined by using the thermogravimetric (TG/DTG) and differential thermal analysis (DTA) techniques. Lignite samples were separated into different size fractions. Experiments were conducted at non-isothermal conditions with a heating rate of 10°C min⁻¹ under nitrogen atmosphere up to 900°C. Pyrolysis regions, maximum pyrolysis rates and characteristic peak temperatures were determined from TG/DTG curves. Thermogravimetric data were analyzed by a reaction rate model assuming first-order kinetics. Apparent activation energy (E) and Arrhenius constant (A _r) of pyrolysis reaction of each particle size fraction were evaluated by applying Arrhenius kinetic model. The apparent activation energies in the essential pyrolysis region were calculated as 27.36 and 28.81 kJ mol⁻¹ for the largest (−2360+2000 μm) and finest (−38 μm) particle sizes, respectively.