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Sample records for dilution alpha spectrometry

  1. Trace uranium analysis in geological sample by isotope dilution-alpha spectrometry and comparison with other techniques

    International Nuclear Information System (INIS)

    Shihomatsu, H.M.; Iyer, S.S.

    1988-12-01

    Establishment of uranium determination in geological samples by alpha spectrometric isotope dilution technique using 233 U tracer is described in the present work. The various steps involved in the method namely, preparation of the sample, electrodeposition, alpha spectrometry, isotope dilution, calculation of the concentration and error statistics are discussed in detail. The experimental parameters for the electrodeposition of uranium, like current density, pH concentration of the electrolyte solution, deposition time, electrode distance were all optimised based on the efficiency of the deposition. The total accuracy and precision of the IDAS using 233 U tracer in the determination of uranium in mineral and granite samples were of the order of 1 to 2% for the concentration range of 50-1500 ppm of U. Our results are compared with those obtained by others workers using similar and different techniques. (author) [pt

  2. The Use of Isotope Dilution Alpha Spectrometry and Liquid Scintillation Counting to Determine Radionuclides in Environmental Samples (abstract)

    Science.gov (United States)

    Bylyku, Elida

    2009-04-01

    In Albania in recent years it has been of increasing interest to determine various pollutants in the environment and their possible effects on human health. The radiochemical procedure used to identify Pu, Am, U, Th, and Sr radioisotopes in soil, sediment, water, coal, and milk samples is described. The analysis is carried out in the presence of respective tracer solutions and combines the procedure for Pu analysis based on anion exchange, the selective method for Sr isolation based on extraction chromatography using Sr-Spec resin, and the application of the TRU-Spec column for separation of Am fraction. An acid digestion method has been applied for the decomposition of samples. The radiochemical procedure involves the separation of Pu from Th, Am, and Sr by anion exchange, followed by the preconcentration of Am and Sr by coprecipitation with calcium oxalate. Am is separated from Sr by extraction chromatography. Uranium is separated from the bulk elements by liquid-liquid extraction using UTEVA® resin. Thin sources for alpha spectrometric measurements are prepared by microprecipitation with NdF3. Two International Atomic Energy Agency reference materials were analyzed in parallel with the samples.

  3. Guideline on Isotope Dilution Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Gaffney, Amy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-05-19

    Isotope dilution mass spectrometry is used to determine the concentration of an element of interest in a bulk sample. It is a destructive analysis technique that is applicable to a wide range of analytes and bulk sample types. With this method, a known amount of a rare isotope, or ‘spike’, of the element of interest is added to a known amount of sample. The element of interest is chemically purified from the bulk sample, the isotope ratio of the spiked sample is measured by mass spectrometry, and the concentration of the element of interest is calculated from this result. This method is widely used, although a mass spectrometer required for this analysis may be fairly expensive.

  4. Alpha spectrometry and secondary ion mass spectrometry of thorium

    International Nuclear Information System (INIS)

    Strisovska, Jana; Kuruc, Jozef; Galanda, Dusan; Matel, Lubomir; Velic, Dusan; Aranyosiova, Monika

    2009-01-01

    A sample of thorium content on steel discs was prepared by electrodeposition with a view to determining the natural thorium isotope. Thorium was determined by alpha spectrometry and by secondary ion mass spectrometry and the results of the two methods were compared

  5. Burn-up determination of irradiated thoria samples by isotope dilution-thermal ionisation mass spectrometry

    International Nuclear Information System (INIS)

    Aggarwal, S.K.; Jaison, P.G.; Telmore, V.M.; Shah, R.V.; Sant, V.L.; Sasibhushan, K.; Parab, A.R.; Alamelu, D.

    2010-03-01

    Burn-up was determined experimentally using thermal ionization mass spectrometry for two samples from ThO 2 bundles irradiated in KAPS-2. This involved quantitative dissolution of the irradiated fuel samples followed by separation and determination of Th, U and a stable fission product burn-up monitor in the dissolved fuel solution. Stable fission product 148 Nd was used as a burn-up monitor for determining the number of fissions. Isotope Dilution-Thermal Ionisation Mass Spectrometry (ID-TIMS) using natural U, 229 Th and enriched 142 Nd as spikes was employed for the determination of U, Th and Nd, respectively. Atom % fission values of 1.25 ± 0.03 were obtained for both the samples. 232 U content in 233 U determined by alpha spectrometry was about 500 ppm and this was higher by a factor of 5 compared to the theoretically predicted value by ORIGEN-2 code. (author)

  6. Determination of plutonium-238 in plutonium by alpha spectrometry

    International Nuclear Information System (INIS)

    Aggarwal, S.K.; Jain, H.C.; Mathews, C.K.; Ramaniah, M.V.

    1975-01-01

    A method is presented for the determination of 238 Pu in plutonium samples by alpha spectrometry. Various factors attributing towards the energy degradation, a problem usually encountered in alpha spectrometry, are discussed. A computer programme is given for the evaluation of peak areas when the alpha spectrum is degraded. The results are compared with those obtained by mass spectrometry. (author)

  7. Automated spike preparation system for Isotope Dilution Mass Spectrometry (IDMS)

    International Nuclear Information System (INIS)

    Maxwell, S.L. III; Clark, J.P.

    1990-01-01

    Isotope Dilution Mass Spectrometry (IDMS) is a method frequently employed to measure dissolved, irradiated nuclear materials. A known quantity of a unique isotope of the element to be measured (referred to as the ''spike'') is added to the solution containing the analyte. The resulting solution is chemically purified then analyzed by mass spectrometry. By measuring the magnitude of the response for each isotope and the response for the ''unique spike'' then relating this to the known quantity of the ''spike'', the quantity of the nuclear material can be determined. An automated spike preparation system was developed at the Savannah River Site (SRS) to dispense spikes for use in IDMS analytical methods. Prior to this development, technicians weighed each individual spike manually to achieve the accuracy required. This procedure was time-consuming and subjected the master stock solution to evaporation. The new system employs a high precision SMI Model 300 Unipump dispenser interfaced with an electronic balance and a portable Epson HX-20 notebook computer to automate spike preparation

  8. Determination of radium-226 by high-resolution alpha spectrometry

    International Nuclear Information System (INIS)

    Sill, C.W.

    1983-01-01

    The determination of radium-226 by alpha spectrometry has been investigated critically to determine experimental conditions under which high resolution and accurate and reliable results can be obtained. Refractory solids such as soils, ores, and tailings from uranium mills are dissolved completely by fusion with potassium fluoride in the presence of barium-133 tracer. The fluoride cake is then transposed with sulfuric acid to a pyrosulfate fusion with simultaneous volatilization of all silica and fluoride. Radium is precipitated with barium already present in the sample by addition of lead perchlorate to a dilute hydrochloric acid solution of the pyrosulfate cake. The resulting insoluble sulfates are dissolved in an alkaline solution of diethylenetriaminepentaacetic acid, and the radium and barium sulfates are reprecipitated with acetic acid. The precipitate is mounted on a membrane filter and analyzed by alpha spectrometry. Water samples are partially evaporated and treated similarly. Resolution of the subsequent alpha spectra is much better than has been achieved previously from barium sulfate, and is almost as good as is obtainable with actinides electrodeposited on polished steel plates. The resolution is about 60 keV full-width-half-maximum with 100 μg of barium on a 1-inch filter with a 450 mm 2 detector at 20% counting efficiency. Recovery is about 97% and accuracy is generally as good as the counting statistics obtained will permit. Grossly inaccurate results can be obtained under certain conditions when barium-133 tracer is used to determine the chemical yield of radium-226. Severe contamination of the surface-barrier detector by polonium-210 and by recoil products of the radium isotopes being counted is demonstrated, amd methods for virtual elimination of both problems are discussed

  9. Isotope dilution-surface ionization mass spectrometry of thallium

    International Nuclear Information System (INIS)

    Murozumi, Masayo; Nakamura, Seiji; Igarashi, Tatsushi

    1978-01-01

    An ultra-micro amount of thallium could be determined by the isotope dilution-surface ionization mass spectrometry by using 203 Tl as a spike. After thallium was separately extracted into 10 ml of 0.00125% dithizone chloroform solution from the solution of the sample isotopically equilibrated with the 203 Tl spike, it was back extracted into 5 ml of 1% nitric acid. The nitric acid solution was treated with a mixture of 0.2 ml of 14 N nitric acid and 0.1 ml of 60% perchloric acid, and evaporated to dryness in a pyrex glass oven supplied with highly pure nitrogen. The residue was dissolved in a mixture of 60 μl of water with 0.015% silica gel suspension and 5 μl of 2% phosphoric acid solution. An aliquot of this mixture was loaded onto a rhenium single filament as an ionization equipment of a Hitachi RMU-6 type mass spectrometer. The detection limit of the present method was 10 -15 -- 10 -14 g for thallium. The precision concerning mass spectroscopic analysis, as a coefficient of variation for the measurements of 205 Tl/ 203 Tl ratios, was 0.1 -- 0.5%. The application of the present method to environmental materials such as Japanese standard rocks and Orchard Leaves delivered by N.B.S. has shown that the precision of repeated analyses was 0.2 -- 0.7% for a concentration of ppm level. This method has revealed that concentration of thallium in the ocean increased with increasing depth at a ppt level. (author)

  10. Performance Test of Alpha Spectrometry for Environmental Radioactivity Analysis

    International Nuclear Information System (INIS)

    Choi, Jung Youn; Yoon, Jong-Ho; Han, Ki-Tek; Ahn, Gil Hoon

    2015-01-01

    Environmental samples are analyzed by various methods such as, ICP-MS (inductively coupled plasma mass spectrometry), AMS (accelerator mass spectrometry) TIMS (thermal ionization mass spectrometry), HRGS (high resolution gamma spectrometry) and alpha /beta particle analysis. In this study, we will described the result of performance test using alpha spectrometry for analyzing environmental samples. Measurement data of the U activity using SRM based on extraction chromatography with UTEVA resin. It should be effective way to separate of uranium isotope for the measurement of alpha spectrometry. But, the result of this measurement data is higher than another recovery data. Also concentration of U data is lack of consistency. We leave out of consideration many effect of factors about influence in the experiment process. In the future work, we will try to reduce the step of experiment process and reflect the uncertainty factors

  11. Determination of radium-226 by high-resolution alpha spectrometry

    International Nuclear Information System (INIS)

    Sill, C.W.

    1983-01-01

    Condition were determined under which high resolution and accurate and reliable results can be obtained. Refractory solids are dissolved completely by fusion with KF and Ba-133 tracer. The fluoride cake is then transposed with sulfuric acid to a pyrosulfate fusion. Radium is precipitated with barium by addition of lead perchlorate to a dilute HCl solution of the pyrosulfate cake. The resulting insoluble sulfates are dissolved in an alkaline solution of DTPA and the Ra and Ba sulfates are reprecipitated with acetic acid to produce very small crystals. The precipitate is mounted on 0.1-μm membrane filter and analyzed by alpha spectrometry. Water samples are partially evaporated and treated similarly. Resolution, almost as good as with actinides electrodeposited on polished steel plates, is about 60 keV full-width-half-maximum with 100 μg of barium on a 1-inch filter with a 450 mm 2 detector at 20% counting efficiency. Recovery is about 97%. One solid sample can be prepared for counting in less than 2 hours. Methods are discussed for ensuring reliability of the results. Severe contamination of the surface-barrier detector by polonium-210 and recoil products is discussed

  12. Concentration of Radon Progeny in Air by Alpha Spectrometry Measurement

    International Nuclear Information System (INIS)

    Acena, M. L.; Crespo, M. T.

    1989-01-01

    The concentration of radon progeny in air has been determined by alpha spectrometry measurement of 214 Po and 318 Po. A known volume of air was passed through a filter, then the alpha activity was directly measured on this filter. (Author) 15 refs

  13. Measurement of radium micro-precipitates using alpha spectrometry and total alpha counting methods

    International Nuclear Information System (INIS)

    Hosseini, T.; Fathivand, A.A.

    2004-01-01

    Background: This study consists of two parts. The first part deals with both qualitative and quantitative analysis of 226 Ra suing alpha spectrometry measurement method. In the second part, the percentage of radioactive equilibrium between 226 Radium and its daughter products were determined by alpha spectrometry and total alpha measurement system after elapsed time of 15 days from precipitation. Materials and methods: Twelve 226 Radium samples as Barium-Radium Sulfate in form of micro-precipitates on millipore and What man 42 filters were prepared. An alpha spectrometer with surface barrier detector and a total alpha measurement system consists of scintillation crystal assembly Zinc Silver were used for counting. Results: The minimum detection limit of alpha spectrometry and total alpha counting for 226 Radium measurements in samples for counting time equal to 10000 seconds, were found to be 3.7 mBq and 15.8 mBq respectively. Results from total alpha counting showed that radioactive equilibrium between 226 Radium and its daughter products reached to about 92%± 3.5, where as, in the case of alpha spectrometry radioactive equilibrium, it was destroyed due to vacuum during counting the sample. Also in case of alpha spectrometry, the optimum sample to detector distance, was found to be 0.5 centimeter. Conclusion: From this study it was concluded that micro-precipitation can be used as a proper method for sample preparation and alpha spectrometry due to its lower detection limit to measure low concentration of 224 Radium and 226 Radium in these precipitates, prepared from different samples. Besides it is not time consuming and sources can be measured immediately after sample preparation

  14. Liquid scintillation alpha particle spectrometry. Progress report

    International Nuclear Information System (INIS)

    Bell, L.L.; Hakooz, S.A.; Johnson, L.O.; Nieschmidt, E.B.; Meikrantz, D.H.

    1979-12-01

    Objective to develop a technique whereby Pu may be put into solution, extracted by solvent extraction into a suitable extractive scintillant and subsequently counted. Presented here are results of attempts to separate beta and alpha activities through pulse shape discrimination. A qualitative discussion is given which yields alpha particle peak widths, resolution and response. The detection efficiency for alpha particles in a liquid scintillant is 100%. Present detection sensitivities of the equipment being used are: 4.5 x 10 -6 μCi (100 s), 1.2 x 10 -6 μCi (1000 s), and 4.0 x 10 -7 μCi (10,000 s) at the 3 sigma level. The detectability of a particular alpha-emitting species is strongly dependent upon the population of other species. The ability to discriminate depends upon the system resolution. 14 figures, 2 tables

  15. Rapid determination of actinides in urine by inductively coupled plasma mass spectrometry and alpha spectrometry: a hybrid approach.

    Science.gov (United States)

    Maxwell, Sherrod L; Jones, Vernon D

    2009-11-15

    A new rapid separation method that allows separation and preconcentration of actinides in urine samples was developed for the measurement of longer lived actinides by inductively coupled plasma mass spectrometry (ICP-MS) and short-lived actinides by alpha spectrometry; a hybrid approach. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration, if required, is performed using a streamlined calcium phosphate precipitation. Similar technology has been applied to separate actinides prior to measurement by alpha spectrometry, but this new method has been developed with elution reagents now compatible with ICP-MS as well. Purified solutions are split between ICP-MS and alpha spectrometry so that long- and short-lived actinide isotopes can be measured successfully. The method allows for simultaneous extraction of 24 samples (including QC samples) in less than 3h. Simultaneous sample preparation can offer significant time savings over sequential sample preparation. For example, sequential sample preparation of 24 samples taking just 15 min each requires 6h to complete. The simplicity and speed of this new method makes it attractive for radiological emergency response. If preconcentration is applied, the method is applicable to larger sample aliquots for occupational exposures as well. The chemical recoveries are typically greater than 90%, in contrast to other reported methods using flow injection separation techniques for urine samples where plutonium yields were 70-80%. This method allows measurement of both long-lived and short-lived actinide isotopes. (239)Pu, (242)Pu, (237)Np, (243)Am, (234)U, (235)U and (238)U were measured by ICP-MS, while (236)Pu, (238)Pu, (239)Pu, (241)Am, (243)Am and (244)Cm were measured by alpha spectrometry. The method can also be adapted so that the separation of uranium isotopes for assay is not required, if uranium assay by direct dilution of the urine sample

  16. RAPID DETERMINATION OF ACTINIDES IN URINE BY INDUCTIVELY-COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY: A HYBRID APPROACH

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, S.; Jones, V.

    2009-05-27

    A new rapid separation method that allows separation and preconcentration of actinides in urine samples was developed for the measurement of longer lived actinides by inductively coupled plasma mass spectrometry (ICP-MS) and short-lived actinides by alpha spectrometry; a hybrid approach. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration, if required, is performed using a streamlined calcium phosphate precipitation. Similar technology has been applied to separate actinides prior to measurement by alpha spectrometry, but this new method has been developed with elution reagents now compatible with ICP-MS as well. Purified solutions are split between ICP-MS and alpha spectrometry so that long- and short-lived actinide isotopes can be measured successfully. The method allows for simultaneous extraction of 24 samples (including QC samples) in less than 3 h. Simultaneous sample preparation can offer significant time savings over sequential sample preparation. For example, sequential sample preparation of 24 samples taking just 15 min each requires 6 h to complete. The simplicity and speed of this new method makes it attractive for radiological emergency response. If preconcentration is applied, the method is applicable to larger sample aliquots for occupational exposures as well. The chemical recoveries are typically greater than 90%, in contrast to other reported methods using flow injection separation techniques for urine samples where plutonium yields were 70-80%. This method allows measurement of both long-lived and short-lived actinide isotopes. 239Pu, 242Pu, 237Np, 243Am, 234U, 235U and 238U were measured by ICP-MS, while 236Pu, 238Pu, 239Pu, 241Am, 243Am and 244Cm were measured by alpha spectrometry. The method can also be adapted so that the separation of uranium isotopes for assay is not required, if uranium assay by direct dilution of the urine sample is preferred instead

  17. 226Ra determination in phosphogypsum by alpha-particle spectrometry

    International Nuclear Information System (INIS)

    Aguado, J.L.; Bolivar, J.P.; Garcia-Tenorio, R.

    1999-01-01

    A radiochemical method for 226 Ra determination by alpha-particle spectrometry in environmental samples has been developed in our laboratory. The method has been validated by measurements in samples with known concentrations of this radionuclide and it has been applied in studies related to 226 Ra behaviour in phosphogypsum (the main by-product of producing phosphoric acid from phosphate rocks). (author)

  18. 226Ra determination in phosphogypsum by alpha-particle spectrometry

    Science.gov (United States)

    Aguado, J. L.; Bolívar, J. P.; García-Tenorio, R.

    1999-01-01

    A radiochemical method for226Ra determination by alpha-particle spectrometry in environmental samples has been developed in our laboratory. The method has been validated by measurements in samples with known concentrations of this radionuclide and it has been applied in studies related to226Ra behaviour in phosphogypsum (the main by-product of producing phosphoric acid from phosphate rocks).

  19. Quantitation of Poly(ADP-Ribose) by Isotope Dilution Mass Spectrometry

    DEFF Research Database (Denmark)

    Zubel, Tabea; Martello, Rita; Bürkle, Alexander

    2017-01-01

    PARP inhibitors, which represent a novel class of promising chemotherapeutics. Previously, we have developed a bioanalytical platform based on isotope dilution mass spectrometry (LC-MS/MS) to quantify cellular PAR with unequivocal chemical specificity in absolute terms with femtomol sensitivity...

  20. Isotope dilution mass spectrometry for nuclear material accountability measurements: dreams and reality

    International Nuclear Information System (INIS)

    Deron, S.; )

    1996-01-01

    Gravimetry, titration, coulometry and isotope dilution mass spectrometry are alternative techniques which can be used to obtain elemental assays of the desirable accuracy. The communication briefly describes the characteristics of the procedure and summarizes a wealth of experience accumulated during actual accountability verification activities

  1. New advanced in alpha spectrometry by liquid scintillation methods

    Energy Technology Data Exchange (ETDEWEB)

    McDowell, W.J.; Case, G.N.

    1979-01-01

    Although the ability to count alpha particles by liquid scintillation methods has been long recognized, limited use has been made of the method because of problems of high background and alpha energy identification. In recent years some new developments in methods of introducing the alpha-emitting nuclide to the scintillator, in detector construction, and in electronics for processing the energy analog and time analog signals from the detector have allowed significant alleviation of the problems of alpha spectrometry by liquid scintillation. Energy resolutions of 200 to 300 keV full peak width at half maximum and background counts of < 0.01 counts/min with rejection with rejection of > 99% of all beta plus gamma interference is now possible. Alpha liquid scintillation spectrometry is now suitable for a wide range of applications, from the accurate quantitative determination of relatively large amounts of known nuclides in laboratory-generated samples to the detection and identification of very small, subpicocurie amounts of alpha emitters in environmental-type samples. Suitable nuclide separation procedures, sample preparation methods, and instrument configurations are available for a variety of analyses.

  2. Simultaneous determination of U and Pu isotopes by alpha spectrometry

    International Nuclear Information System (INIS)

    Equillor, H.E.; Campos, J.M.

    2011-01-01

    Determination of actinides by alpha spectrometry is usually carried out after full separation of each of the components of the sample. The procedure presented in this paper permits U and Pu isotopes to be measured together allowing faster sample processing and measurement. The method consists in the extraction with tributyl phosphate of U and Pu isotopes from the rest of the matrix, followed by a cathodic electrodeposition to obtain alpha spectrometry suitable pieces. It can be applied to various environmental samples, such as water, filters and soil (about 0.5 g of solid sample for the described conditions). High-quality electroplated discs are essential for simultaneous processing, so a technique to achieve this requirement is also explained. (authors) [es

  3. Determination of Ra in environmental samples by. alpha. -particle spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hancock, G.J.; Martin, P. (Alligator Rivers Region Research Inst., Jabiru, N.T. (Australia))

    1991-01-01

    A method of determining Ra isotopes by {alpha}-particle spectrometry using {sup 225}Ra as a yield tracer has been developed. Radium is coprecipitated with lead sulphate, purified using ion exchange techniques, and electrodeposited from an aqueous/ethanol solution. The procedure can be easily completed in 1 day. Tracer recoveries are typically 80%, and the resolution obtained is typically 40 keV FWHM. (author).

  4. Approach for domestic preparation of standard material (LSD spike) for isotope dilution mass spectrometry

    International Nuclear Information System (INIS)

    Ishikawa, Fumitaka; Sumi, Mika; Chiba, Masahiko; Suzuki, Toru; Abe, Tomoyuki; Kuno, Yusuke

    2008-01-01

    The accountancy analysis of the nuclear fuel material at Plutonium Fuel Development Center of JAEA is performed by isotope dilution mass spectrometry (IDMS; Isotope Dilution Mass Spectrometry). IDMS requires the standard material called LSD spike (Large Size Dried spike) which is indispensable for the accountancy in the facilities where the nuclear fuel materials are handled. Although the LSD spike and Pu source material have been supplied from foreign countries, the transportation for such materials has been getting more difficult recently. This difficulty may affect the operation of nuclear facilities in the future. Therefore, research and development of the domestic LSD spike and base material has been performed at JAEA. Certification for such standard nuclear materials including spikes produced in Japan is being studied. This report presents the current status and the future plan for the technological development. (author)

  5. Total cholesterol in serum determined by isotope dilution/mass spectrometry, with liquid-chromatographic separation

    International Nuclear Information System (INIS)

    Takatsu, Akiko; Nishi, Sueo

    1988-01-01

    We describe an accurate, precise method for determination of total serum cholesterol by isotope dilution/mass spectrometry (IDMS) with liquid chromatographic separation. After adding [3,4- 13 C] cholesterol to serum and hydrolyzing the cholesterol esters, we extract the total cholesterol. High-performance liquid chromatography (HPLC) is used to separate the extracted cholesterol for measurement by electron-impact mass spectrometry with use of a direct-insertion device. To evaluate the specificity and the accuracy of this method, we also studied the conventional IDMS method, which involves converting cholesterol to the trimethylsilyl ether and assay by gas chromatography-mass spectrometry with use of a capillary column. The coefficient of variation for the HPLC method was a little larger than for the conventional method, but mean values by each method agreed within 1% for all sera tested. (author)

  6. DIURNAL CHANGES IN PLASMA-LEVELS OF 2-PYRROLIDINONE DETERMINED BY ISOTOPE-DILUTION MASS-SPECTROMETRY

    NARCIS (Netherlands)

    VANDENBERG, GA; WOLTHERS, BG; NAGEL, GT; MUSKIET, FAJ; BANGHMAN, S; DEZEEUW, RA

    1991-01-01

    A new capillary gas chromatographic method with mass spectrometric detection for the determination of 2-pyrrolidinone was developed. Using quantification based on stable isotope dilution mass spectrometry by monitoring selected ions in the ammonia chemical ionization mode diurnal changes of

  7. Response of commercial photodiodes for application in alpha spectrometry

    International Nuclear Information System (INIS)

    Ferreira Filho, Alfredo Lopes

    1998-06-01

    The use of semiconductor detector for ionizing radiations spectrometry and dosimetry has been growing in the last years due to its characteristics of fast response, good efficiency for unit of volume and excellent resolution. Since the working principle of a semiconductor detector is identical to that of the semiconductor junctions of commercial electronic devices, a study was carried out on the PIN-photodiodes response, aiming at set up an alpha spectrometry system of low cost and easy acquisition. The tested components have the following characteristics: active area varying between 13.2 and 25 mm 2 , window of thickness equal or lower than 57 mg/cm 2 , depletion area with depth ranging from 10 to 300 μm and junction capacitance of 16 to 20 pF.Am-241, Cm-244, U-233 and Np-237 alpha sources produced by electrodeposition were used to evaluate the response of the devices as a function of the radiation energy. The results have shown a linear response of the photodiodes with the incident alpha particle energy. The resolution varied from 1.6% to 0.45% and the better detection efficiency found was about 7.2. The low cost of the photodiodes and the excellent results obtained at room temperature make such components very attractive for teaching purposes for environmental monitoring. (author)

  8. Iterative inversion of gamma or alpha spectrometry data

    International Nuclear Information System (INIS)

    Nordemann, D.J.R.

    1985-12-01

    Gamma - and alpha ray spectrometry data are processed by an iterative regression method (Wolberg, 1967) to obtain the activities or yields of radionuclides. This method, applied to Nuclear Geophysics Research, permits the use of either selected energy bands or of all the channels one by one. It may be easily programmed in popular microcomputers and offers many advantages such as the use of mixtures of radionuclides for the calibrations and the treatment of the uncertainties on the measurements and results. Several conclusions about the method and options of nuclear data processing are presented. (Author) [pt

  9. Chemical vapor deposition (CVD) of uranium for alpha spectrometry

    International Nuclear Information System (INIS)

    Ramirez V, M. L.; Rios M, C.; Ramirez O, J.; Davila R, J. I.; Mireles G, F.

    2015-09-01

    The uranium determination through radiometric techniques as alpha spectrometry requires for its proper analysis, preparation methods of the source to analyze and procedures for the deposit of this on a surface or substrate. Given the characteristics of alpha particles (small penetration distance and great loss of energy during their journey or its interaction with the matter), is important to ensure that the prepared sources are thin, to avoid problems of self-absorption. The routine methods used for this are the cathodic electro deposition and the direct evaporation, among others. In this paper the use of technique of chemical vapor deposition (CVD) for the preparation of uranium sources is investigated; because by this, is possible to obtain thin films (much thinner than those resulting from electro deposition or evaporation) on a substrate and comprises reacting a precursor with a gas, which in turn serves as a carrier of the reaction products to achieve deposition. Preliminary results of the chemical vapor deposition of uranium are presented, synthesizing and using as precursor molecule the uranyl acetylacetonate, using oxygen as carrier gas for the deposition reaction on a glass substrate. The uranium films obtained were found suitable for alpha spectrometry. The variables taken into account were the precursor sublimation temperatures and deposition temperature, the reaction time and the type and flow of carrier gas. Of the investigated conditions, two depositions with encouraging results that can serve as reference for further work to improve the technique presented here were selected. Alpha spectra obtained for these depositions and the characterization of the representative samples by scanning electron microscopy and X-ray diffraction are also presented. (Author)

  10. Certification of mercury in acrylonitrile butadiene styrene by using isotope dilution mass spectrometry

    International Nuclear Information System (INIS)

    Hu Hai; Ma Liandi; Wei Chao; Zhou Tao; Wang Jun; Zhao Motian; Li Jinying

    2008-01-01

    Under the framework of a co-certification system for the development of Certified Reference Materials (CRMs) among China, Japan and Korea, the 1st co-certification campaign of mercury in acrylonitrile butadiene styrene (ABS) for Japanese CRMs was taken. In this campaign isotope dilution mass spectrometry (IDMS) was used. First, all abundances of Hg in spike 202 Hg, CRM and ABS were analyzed by MC-ICP-MS before the certification. Then the concentrations of 202 Hg and Hg in ABS were determined with IDMS by Q-ICP-MS. A new procedure to reduce memory effect was used. first, dilute with 5 μg/g Au solution for 1 min; then, 5 μg/g EDTA solution for 2 min. The results accord to each other very well and this implies that the co-certification system can run swimmingly. (authors)

  11. Standard practice for mounting actinides for alpha spectrometry using neodymium fluoride

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This practice covers the preparation of separated fractions of actinides for alpha spectrometry as an alternate to electrodeposition. It is applicable to any of the actinides that can be dissolved in dilute hydrochloric acid. Examples of applicable samples would be the final elution from an ion exchange separation or the final strip from a solvent extraction separation. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see Section 9.

  12. Field ionization mass spectrometry (FIMS) applied to tracer studies and isotope dilution analysis

    International Nuclear Information System (INIS)

    Anbar, M.; Heck, H.d'A.; McReynolds, J.H.; St John, G.A.

    1975-01-01

    The nonfragmenting nature of field ionization mass spectrometry makes it a preferred technique for the isotopic analysis of multilabeled organic compounds. The possibility of field ionization of nonvolatile thermolabile materials significantly extends the potential uses of this technique beyond those of conventional ionization methods. Multilabeled tracers may be studied in biological systems with a sensitivity comparable to that of radioactive tracers. Isotope dilution analysis may be performed reliably by this technique down to picogram levels. These techniques will be illustrated by a number of current studies using multilabeled metabolites and drugs. The scope and limitations of the methodology are discussed

  13. Determination of plutonium isotopes in bilberry using liquid scintillation spectrometry and alpha-particle spectrometry

    International Nuclear Information System (INIS)

    Seferinoğlu, Meryem; Aslan, Nazife; Kurt, Aylin; Erden, Pınar Esra; Mert, Hülya

    2014-01-01

    This paper presents α-particle spectrometry and liquid scintillation spectrometry methods to determine plutonium isotopes in bilberry. The analytical procedure involves sample preparation steps for ashing, digestion of bilberry samples, radiochemical separation of plutonium radioisotopes and their measurement. The validity of the method was checked for coherence using the ζ test, z-test, relative bias and relative uncertainty outlier tests. The results indicated that the recommended procedures for both measurement systems could be successfully applied for the accurate determination of plutonium activities in bilberry samples. - Highlights: • Sample preparation methods for Pu using LSS and alpha spectrometry developed. • Complete separation of plutonium from interfering radionuclides. • Commercial bilberry was spiked with NPL 2011 (AH-B11144) proficiency test sample. • Results were checked using ζ test, z-test, rel. bias and rel. uncert. outlier tests. • Recommended procedures successfully applied to bilberry samples

  14. Performance of alpha spectrometry in the analysis of uranium isotopes in environmental and nuclear materials

    International Nuclear Information System (INIS)

    Carvalho, F.P.; Oliveira, J.M.

    2009-01-01

    The accuracy of alpha spectrometry in the determination of uranium isotopes at various concentrations levels and with various isotope ratios was tested in a round robin international intercomparison exercise. Results of isotope activity/mass and isotope mass ratios obtained by alpha spectrometry were accurate in a wide range of uranium masses and in isotopic ratios typical of depleted, natural, and low enriched uranium samples. Determinations by alpha spectrometry compared very satisfactorily in accuracy with those by mass spectrometry. For example, determination of U isotopes in natural uranium by alpha spectrometry agreed with mass spectrometry determinations at within ±1%. However, the 236 U isotope, particularly if present in activities much lower than 235 U, might not be determined accurately due to overlap in the alpha particle energies of these two uranium isotopes. (author)

  15. Detection and quantification of ricin in beverages using isotope dilution tandem mass spectrometry.

    Science.gov (United States)

    McGrath, Sara C; Schieltz, David M; McWilliams, Lisa G; Pirkle, James L; Barr, John R

    2011-04-15

    The toxic plant protein ricin has gained notoriety due to wide availability and potential use as a bioterrorism agent, with particular concern for food supply contamination. We have developed a sensitive and selective mass spectrometry-based method to detect ricin in tap water, 2% milk, apple juice, and orange juice. Ricin added to beverage matrices was extracted using antibody-bound magnetic beads and digested with trypsin. Absolute quantification was performed using isotope dilution mass spectrometry with a linear ion trap operating in product-ion-monitoring mode. The method allows for identification of ricin A chain and B chain and for distinction of ricin from ricin agglutinin within a single analytical run. Ricin-bound beads were also tested for deadenylase activity by incubation with a synthetic ssDNA oligomer. Depurination of the substrate by ricin was confirmed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOFMS). This method was used successfully to extract ricin from each beverage matrix. The activity of recovered ricin was assessed, and quantification was achieved, with a limit of detection of 10 fmol/mL (0.64 ng/mL). © 2011 American Chemical Society

  16. Improved analytical procedure for the determination of 210Pb and 210Po using alpha-spectrometric isotope dilution

    International Nuclear Information System (INIS)

    Urnezis, P.W.; Holtzman, R.B.

    1981-01-01

    An isotope dilution method has been incorporated into the 210 Pb- 210 Po analysis. A known amount of 209 Po is added to the sample before analysis. Then both 209 Po and 210 Po are deposited on a silver planchet which is assayed in an alpha spectrometer to determine the activities of each isotope. The recoveries generally range from 70% to 90%

  17. Alpha spectrometry enriched uranium urinalysis results from IPEN

    International Nuclear Information System (INIS)

    Lima, Marina Ferreira

    2008-01-01

    Full text: IPEN (Instituto de Pesquisas Energeticas e Nucleares) manufactures the nuclear fuel to its research reactor, the IEA-R1. The CCN (Centro do Ciclo do Combustivel) facility produces the fuel cermets from UF 6 (uranium hexafluoride) enriched to 19.75% in 235 U. The production involves the transformation of the gaseous form in oxides and silicates by ceramic and metallurgical processing. The workers act in more than one step that involves exposition to types F, S and M compounds of uranium. Until 2003, only fluorimetric analysis was carried out by the LRT (Laboratorio de Radiotoxicologia - IPEN) in order to evaluate the intake of uranium, in spite of the sub estimation of the 234 U contribution to the internal doses. Isotopic uranium determination in urine by alpha spectrometry is the current method to monitoring the contribution of 234 U, 235 U and 238 U. Alpha spectrometry data of 164 samples from 84 individuals separate in three categories of workers: routinely work group; special operation group and control group - were analyzed how the isotopic composition excreted by urinary tract corresponds with the level of enrichment and isotopic composition of the plant products. Results show that is hard to estimate these intakes of 234 U and 235 U since these isotopes alpha activities are below the limit of detection or minimum detectable activity (MAD) of this method in the most part of the samples. Only in 22 samples it was possibly to measure the three radionuclides. Not expected high contribution of 234 U activity was found in samples of the control group. No one result over the 234 U and 235 U MAD was found in the samples from the special operation group. Only in 5 samples from the routinely group the levels of 235 U was higher than the levels of others groups. In a complementary study, 3 solid samples of UF 6 , U 2 O 8 and U 3 Si 2 from CCN plant were analyzed to determinate the isotopic uranium composition in these salts, since this composition varies

  18. Rapid assay of resveratrol in red wine by paper spray tandem mass spectrometry and isotope dilution.

    Science.gov (United States)

    Di Donna, Leonardo; Taverna, Domenico; Indelicato, Serena; Napoli, Anna; Sindona, Giovanni; Mazzotti, Fabio

    2017-08-15

    A rapid analytical approach for the assay of resveratrol in red wines, based on Paper Spray Mass Spectrometry (PS-MS) and Multiple Reaction Monitoring (MRM) is described. The assay involves the use of the stable isotope dilution method. The analytical parameters calculated analyzing fortified samples confirm the reliability of the proposed approach, with accuracy values about 100%, and LOD and LOQ values calculated at 0.5 and 0.8μg/mL, respectively. Furthermore, both the recovery, which was quantitative for the analyte, and the reproducibility (RSD%), checked on different days on the same wine, always below 7%, highlighted the consistency of the methodology. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Hot vacuum extraction-isotopic dilution mass spectrometry for determination of hydrogen isotopes in zircaloys

    International Nuclear Information System (INIS)

    Shi, Y.; Leeson, P.K.; Wilkin, D.; Britton, A.; Macleod, R.

    2016-01-01

    A hot vacuum extraction-isotope dilution mass spectrometry (HVE-IDMS) was studied for determination of hydrogen isotopes in zirconium metal and alloys as nuclear reactor materials. A theoretical assessment of the completeness of the extraction of hydrogen isotopes under the chosen condition was carried out based on the hydrogen and deuterium solubility data for zirconium. The optimal isotopic spiking condition for conventional IDMS was further explored for the special case IDMS where the isotope abundance of the samples is varied and non-natural. Applying the optimal conditions, the accurate IDMS determination was realized. The agreement between the measured values and the certified or prepared values of standard reference materials and homemade standard materials validate the method developed. (author)

  20. Isotope-dilution mass spectrometry in the measurement of plutonium isotope half-lives

    International Nuclear Information System (INIS)

    Abernathey, R.M.; Marsh, S.F.

    1981-01-01

    Isotope-dilution mass spectrometry has been used at Los Alamos to measure the half-lives of 239 Pu, 240 Pu, and 241 Pu. The latter was determined by measuring the rate of decrease of the 241 Pu/ 242 Pu ratio in an appropriate isotopic mixture over a period of several years. The half-lives of the two lighter isotopes are too long to be determined in this manner. They were determined by measuring the rate of production of the uranium daughter relative to a known added 233 U spike. Experimental procedures were designed to control sources of error and to permit a detailed statistical treatment which included all known sources of error and accounted for all covariances. The uncertainties, at the 95% confidence level, associated with the measured half-lives were less than 0.4% for 241 Pu and less than 0.2% for 239 Pu and 240 Pu

  1. Determination of 239Pu/240Pu isotopic ratio by high resolution alpha-particle spectrometry

    International Nuclear Information System (INIS)

    Amoudry, F.; Burger, P.

    1983-05-01

    The development of passivated ion-implanted silicon detectors and of very thin alpha-particle sources improves the resolution of alpha-particle spectra and allows to separate energy pics up to now unseparate. The 239 Pu/ 240 Pu isotopic ratio of a mixture has been measured using the alpha spectrometry deconvolution code DEMO [fr

  2. Serum/plasma methylmercury determination by isotope dilution gas chromatography-inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, Douglas C., E-mail: douglas.baxter@alsglobal.com [ALS Scandinavia AB, Aurorum 10, 977 75 Lulea (Sweden); Faarinen, Mikko [ALS Scandinavia AB, Aurorum 10, 977 75 Lulea (Sweden); Osterlund, Helene; Rodushkin, Ilia [ALS Scandinavia AB, Aurorum 10, 977 75 Lulea (Sweden); Division of Geosciences, Lulea University of Technology, 977 87 Lulea (Sweden); Christensen, Morten [ALS Scandinavia AB, Maskinvaegen 2, 183 53 Taeby (Sweden)

    2011-09-09

    Highlights: {center_dot} We determine methylmercury in serum and plasma using isotope dilution calibration. {center_dot} Separation by gas chromatography and detection by inductively coupled plasma mass spectrometry. {center_dot} Data for 50 specimens provides first reference range for methylmercury in serum. {center_dot} Serum samples shown to be stable for 11 months in refrigerator. - Abstract: A method for the determination of methylmercury in plasma and serum samples was developed. The method uses isotope dilution with {sup 198}Hg-labeled methylmercury, extraction into dichloromethane, back-extraction into water, aqueous-phase ethylation, purge and trap collection, thermal desorption, separation by gas chromatography, and mercury isotope specific detection by inductively coupled plasma mass spectrometry. By spiking 2 mL sample with 1.2 ng tracer, measurements in a concentration interval of (0.007-2.9) {mu}g L{sup -1} could be performed with uncertainty amplification factors <2. A limit of quantification of 0.03 {mu}g L{sup -1} was estimated at 10 times the standard deviation of concentrations measured in preparation blanks. Within- and between-run relative standard deviations were <10% at added concentration levels of 0.14 {mu}g L{sup -1}, 0.35 {mu}g L{sup -1} and 2.8 {mu}g L{sup -1}, with recoveries in the range 82-110%. Application of the method to 50 plasma/serum samples yielded a median (mean; range) concentration of methylmercury of 0.081 (0.091; <0.03-0.19) {mu}g L{sup -1}. This is the first time methylmercury has been directly measured in this kind of specimen, and is therefore the first estimate of a reference range.

  3. Determination of zinc stable isotopes in biological materials using isotope dilution inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Patterson, K.Y.; Veillon, Claude

    1992-01-01

    A method is described for using isotope dilution to determine both the amount of natural zinc and enriched isotopes of zinc in biological samples. Isotope dilution inductively coupled plasma mass spectrometry offers a way to quantify not only the natural zinc found in a sample but also the enriched isotope tracers of zinc. Accurate values for the enriched isotopes and natural zinc are obtained by adjusting the mass count rate data for measurable instrumental biases. Analytical interferences from the matrix are avoided by extracting the zinc from the sample matrix using diethylammonium diethyldithiocarbamate. The extraction technique separates the zinc from elements which form interfering molecular ions at the same nominal masses as the zinc isotopes. Accuracy of the method is verified using standard reference materials. The detection limit is 0.06 μg Zn per sample. Precision of the abundance ratios range from 0.3-0.8%. R.S.D. for natural zinc concentrations is about 200-600 μg g -1 . The accuracy and precision of the measurements make it possible to follow enriched isotopic tracers of zinc in biological samples in metabolic tracer studies. (author). 19 refs.; 1 fig., 4 tabs

  4. Sulfur-based absolute quantification of proteins using isotope dilution inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Lee, Hyun-Seok; Heun Kim, Sook; Jeong, Ji-Seon; Lee, Yong-Moon; Yim, Yong-Hyeon

    2015-10-01

    An element-based reductive approach provides an effective means of realizing International System of Units (SI) traceability for high-purity biological standards. Here, we develop an absolute protein quantification method using double isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP-MS) combined with microwave-assisted acid digestion for the first time. We validated the method and applied it to certify the candidate protein certified reference material (CRM) of human growth hormone (hGH). The concentration of hGH was determined by analysing the total amount of sulfur in hGH. Next, the size-exclusion chromatography method was used with ICP-MS to characterize and quantify sulfur-containing impurities. By subtracting the contribution of sulfur-containing impurities from the total sulfur content in the hGH CRM, we obtained a SI-traceable certification value. The quantification result obtained with the present method based on sulfur analysis was in excellent agreement with the result determined via a well-established protein quantification method based on amino acid analysis using conventional acid hydrolysis combined with an ID liquid chromatography-tandem mass spectrometry. The element-based protein quantification method developed here can be generally used for SI-traceable absolute quantification of proteins, especially pure-protein standards.

  5. Determination of thyroid hormones in mouse tissues by isotope-dilution microflow liquid chromatography-mass spectrometry method

    DEFF Research Database (Denmark)

    De Angelis, Meri; Giesert, Florian; Finan, Brian

    2016-01-01

    selectivity. In the last decade, several analytical methods using liquid chromatography-mass spectrometry (LC-MS) and tandem mass spectrometry (LC-MS/MS) have been developed to measure THs. These new techniques proved to be more accurate than the IA analysis and they were widely used for the determination......, (13)C6-T3, (13)C6-rT3, (13)C6-T2) dilution liquid chromatography-mass spectrometry. The major difference with previously described methods lies in the utilization of a nano-UPLC (Ultra Performance Liquid Chromatography) system in micro configuration. This approach leads to a reduction compared...

  6. Evaluation of online carbon isotope dilution mass spectrometry for the purity assessment of synthetic peptide standards

    Energy Technology Data Exchange (ETDEWEB)

    Díaz, Sergio Cueto; Ruiz Encinar, Jorge, E-mail: ruizjorge@uniovi.es; García Alonso, J. Ignacio, E-mail: jiga@uniovi.es

    2014-09-24

    Highlights: • Purity assessment of peptide standards applicable to any water soluble peptide. • Online {sup 13}C isotope dilution mass spectrometry. • Mass flow chromatogram from measured 44/45 isotope ratios. • Validation by the analysis of NIST 8327. - Abstract: We present a novel method for the purity assessment of peptide standards which is applicable to any water soluble peptide. The method is based on the online {sup 13}C isotope dilution approach in which the peptide is separated from its related impurities by liquid chromatography (LC) and the eluent is mixed post-column with a continuous flow of {sup 13}C-enriched sodium bicarbonate. An online oxidation step using sodium persulfate in acidic media at 99 °C provides quantitative oxidation to {sup 12}CO{sub 2} and {sup 13}CO{sub 2} respectively which is extracted to a gaseous phase with the help of a gas permeable membrane. The measurement of the isotope ratio 44/45 in the mass spectrometer allows the construction of the mass flow chromatogram. As the only species that is finally measured in the mass spectrometer is CO{sub 2}, the peptide content in the standard can be quantified, on the base of its carbon content, using a generic primary standard such as potassium hydrogen phthalate. The approach was validated by the analysis of a reference material (NIST 8327), and applied to the quantification of two commercial synthetic peptide standards. In that case, the results obtained were compared with those obtained using alternative methods, such as amino acid analysis and ICP-MS. The results obtained proved the value of the method for the fast, accurate and precise mass purity assignment of synthetic peptide standards.

  7. Protein quantification by isotope dilution mass spectrometry of proteolytic fragments: cleavage rate and accuracy.

    Science.gov (United States)

    Arsene, Cristian G; Ohlendorf, Rüdiger; Burkitt, William; Pritchard, Caroline; Henrion, André; O'Connor, Gavin; Bunk, David M; Güttler, Bernd

    2008-06-01

    attainable in quantification of "small" organic molecules using liquid chromatography/isotope dilution mass spectrometry.

  8. Quantification of four artificial sweeteners in Finnish surface waters with isotope-dilution mass spectrometry.

    Science.gov (United States)

    Perkola, Noora; Sainio, Pirjo

    2014-01-01

    The artificial sweeteners sucralose (SCL), acesulfame (ACS), saccharin (SAC), and cyclamate (CYC) have been detected in environmental waters in Europe and North America. Higher environmental levels are expected in view of the increasing consumption of these food additives. In this study, an isotope-dilution mass spectrometry (IDMS) LC-MS/MS method was developed and validated for quantifying the four artificial sweeteners in boreal lakes (n = 3) and rivers (n = 12). The highest concentrations of ACS, SAC, CYC and SCL were 9,600, 490, 210 and 1000 ng/L, respectively. ACS and SAC were detected in all studied samples, and CYC and SCL in 98% and 56% of the samples. Seasonal trends of ACS and SAC were observed in some rivers. ACS and SCL concentrations in rivers correlated linearly with population equivalents of the wastewater treatment plants in the catchment areas, whereas SAC and CYC concentrations depend more on the source. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Oxygen diluted hexamethyldisiloxane plasmas investigated by means of in situ infrared absorption spectroscopy and mass spectrometry

    Science.gov (United States)

    Magni, D.; Deschenaux, Ch; Hollenstein, Ch; Creatore, A.; Fayet, P.

    2001-01-01

    The gas phase species produced in rf plasmas of hexamethyldisiloxane (HMDSO), Si2O(CH3)6, diluted with oxygen, have been investigated. The complementarity of Fourier transform infrared absorption spectroscopy and mass spectrometry allows the determination of the most abundant neutral components present in the discharge. The measurements reveal that methyl groups (CH3), abundantly formed by the dissociation of the HMDSO molecule, are the precursor for the most abundant species which stem from two kinds of reaction. The first kind of reaction is combustion of CH3 by oxygen-producing formaldehyde (COH2), formic acid (CO2H2), carbon monoxide (CO), carbon dioxide (CO2) and water. It is shown that high mass carbonated radicals, such as SixOyCzHt, first diffuse to the surface and then the carbon is removed by oxygen etching to form CO2. The second is hydrocarbon chemistry promoted by CH3, producing mainly hydrogen (H2), methane (CH4) and acetylene (C2H2).

  10. Quantification of four artificial sweeteners in Finnish surface waters with isotope-dilution mass spectrometry

    International Nuclear Information System (INIS)

    Perkola, Noora; Sainio, Pirjo

    2014-01-01

    The artificial sweeteners sucralose (SCL), acesulfame (ACS), saccharin (SAC), and cyclamate (CYC) have been detected in environmental waters in Europe and North America. Higher environmental levels are expected in view of the increasing consumption of these food additives. In this study, an isotope-dilution mass spectrometry (IDMS) LC–MS/MS method was developed and validated for quantifying the four artificial sweeteners in boreal lakes (n = 3) and rivers (n = 12). The highest concentrations of ACS, SAC, CYC and SCL were 9,600, 490, 210 and 1000 ng/L, respectively. ACS and SAC were detected in all studied samples, and CYC and SCL in 98% and 56% of the samples. Seasonal trends of ACS and SAC were observed in some rivers. ACS and SCL concentrations in rivers correlated linearly with population equivalents of the wastewater treatment plants in the catchment areas, whereas SAC and CYC concentrations depend more on the source. -- Highlights: • A reliable method for analysing artificial sweeteners in water was validated. • Artificial sweeteners were quantified in boreal rivers and lakes. • Most concentrations were in accordance with previous European studies. • Acesulfame and saccharine concentrations were high in the most contaminated rivers. • Correlation observed between concentrations and mean water throughflow in rivers. -- High concentrations of artificial sweeteners were obtained, which indicates slow or negligible degradation of these compounds in boreal surface waters

  11. Alpha and gamma spectrometry for natural radioactive nuclides around uranium mines and nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, A.M.; Tome, F.V.; Bejarano, J.D.; Aparicio, A.G. (Universidad de Extremadura, Badajoz (Spain). Dept. de Fisica)

    1992-01-01

    Concentration of uranium and [sup 234]U/[sup 238]U and [sup 235]U/[sup 238]U activity ratios were studied in water samples taken in the neighbourhood of two uranium mines ('El Lobo' and 'El Pedregal', Badajoz, Spain), and around two nuclear power plants and their cooling reservoirs (the Central Nuclear de Almaraz, which is working today, and the Central Nuclear de Valdecaballeros, which is in the construction phase), using alpha spectrometry with semiconductor detectors. The Valdecaballeros data were taken to check for comparison with those of the Central Nuclear de Almaraz and with future values after the start of operation. Measurements were also made of all soluble gamma emitting nuclides using a shielded coaxial high purity germanium detector. The data suggest that the mechanisms responsible for the changes in the concentrations and in the [sup 234]U/[sup 238]U activity ratios in surface waters are principally dilution and leaching. (author).

  12. Automated isotope dilution liquid chromatography-tandem mass spectrometry with on-line dilution and solid phase extraction for the measurement of cortisol in human serum sample.

    Science.gov (United States)

    Kawaguchi, Migaku; Eyama, Sakae; Takatsu, Akiko

    2014-08-05

    A candidate reference measurement procedure involving automated isotope dilution coupled with liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) with on-line dilution and solid phase extraction (SPE) has been developed and critically evaluated. We constructed the LC-MS/MS with on-line dilution and SPE system. An isotopically labelled internal standard, cortisol-d4, was added to serum sample. After equilibration, the methanol was added to the sample, and deproteination was performed. Then, the sample was applied to the LC-MS/MS system. The limit of detection (LOD) and limit of quantification (LOQ) were 0.2 and 1ngg(-1), respectively. Excellent precision was obtained with within-day variation (RSD) of 1.9% for ID-LC-MS/MS analysis (n=6). This method, which demonstrates simple, easy, good accuracy, high precision, and is free from interferences from structural analogues, qualifies as a reference measurement procedure. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Quantitative Analysis of Ingenol in Euphorbia species via Validated Isotope Dilution Ultra-high Performance Liquid Chromatography Tandem Mass Spectrometry

    Czech Academy of Sciences Publication Activity Database

    Béres, T.; Dragull, K.; Pospíšil, Jiří; Tarkowská, Danuše; Dančák, M.; Bíba, Ondřej; Tarkowski, P.; Doležal, K.; Strnad, Miroslav

    2018-01-01

    Roč. 29, č. 1 (2018), s. 23-29 ISSN 0958-0344 R&D Projects: GA ČR GA17-14007S; GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Euphorbia genus * ingenol * isotope-dilution method * mass spectrometry * ultra-high performance liquid chromatography Subject RIV: FD - Oncology ; Hematology OBOR OECD: Analytical chemistry Impact factor: 2.292, year: 2016

  14. Determination of environmental actinide nuclides and 210Pb (210Po) by low-energy photon spectrometry with alpha-spectrometry

    International Nuclear Information System (INIS)

    Sakanoue, Masanobu; Yamamoto, M.; Komura, Kazuhisa

    1987-01-01

    Low-energy photon spectrometry with alpha spectrometry was used to determine the environmental concentrations of low-level actinides and other nuclides, especially 210 Pb and 210 Po. The isotopic ratio of 2 40 Pu/ 239 Pu was successfully determined by measuring L x -ray/α-ray counting ratio. A reliable method was developed for the determination of extremely low-level 237 Np global fallout in environmental samples. The non-destructive determination by Ge-LEPS for natural 210 Pb in various samples (tobacco leaves, commercially available tobacco, etc.) was also carried out with the determination of 210 Po by alpha spectrometry using 209 Po as a yield tracer. (author) 6 refs.; 5 tabs

  15. Development of an electrothermal atomization laser-excited atomic fluorescence spectrometry procedure for direct measurements of arsenic in diluted serum.

    Science.gov (United States)

    Swart, D J; Simeonsson, J B

    1999-11-01

    A procedure for the direct determination of arsenic in diluted serum by electrothermal atomization laser-excited atomic fluorescence spectrometry (ETA-LEAFS) is reported. Laser radiation needed to excite As at 193.696 and 197.197 nm is generated as the second anti-Stokes stimulated Raman scattering output of a frequency-doubled dye laser operating near 230.5 and 235.5 nm, respectively. Two different LEAFS schemes have been utilized and provide limits of detection of 200-300 fg for As in aqueous standards. When measurements of serum samples diluted 1:10 with deionized water are performed, a stable background signal is observed that can be accounted for by taking measurements with the laser tuned off-wavelength. No As is detected in any of the bovine or human serum samples analyzed. Measurements of 100 pg/mL standard additions of As to a diluted bovine serum sample utilizing either inorganic or organic As species demonstrate a linear relationship of the fluorescence signal to As spike concentration, but exhibit a sensitivity of approximately half that observed in pure aqueous standards. The limit of detection for As in 1:10 diluted serum samples is 65 pg/mL or 650 fg absolute mass, which corresponds to 0.65 ng/mL As in undiluted serum. To our knowledge, the ETA-LEAFS procedure is currently the only one capable of directly measuring As in diluted serum at these levels.

  16. Experiences with large-area frisch grid chambers in low-level alpha spectrometry

    International Nuclear Information System (INIS)

    Hoetzl, H.; Winkler, R.

    1984-01-01

    The properties of parallel-plate gridded ionization chambers with areas of 300 cm 2 , developed by us for alpha spectrometry of samples with low specific alpha activity are reported. Several practical hints for optimum operating conditions are presented. The chambers can be operated routinely at atmospheric pressure for several days, without the need for purification of the gas filling (P10). The minimum detectable activity at 5 MeV is 0.01 pCi, based on 4.65 standard deviations of background and 1000 min counting time. At the GSF Research Center ionization chambers of this type are used for the analysis of natural alpha emitters, as well as of transuranium nuclides in environmental samples by: a) direct alpha spectrometry without any previous treatment of the sample, b) semi-direct spectrometry after removal of organic matter by low-temperature ashing and c) spectrometry after chemical separation. Some typical example of application are given. Furthermore the range of application of the chambers in comparison to semiconductor detectors in the field of low-level alpha spectrometry is discussed. (orig.)

  17. Radiometric dating by alpha spectrometry on uranium series nuclides

    NARCIS (Netherlands)

    Wijk, Albert van der

    1987-01-01

    De Engelse titel van dit proegschrift \\"Radiometric Dating by Alpha Spectometry on Uranium Series Nuclides\\" kan in het Nederlands wellicht het best worden weergegeven door \\"ouderdomsdbepalingen door stralingsmeting aan kernen uit de uraniumreeks met behulp van alfaspectometrie\\". In dit laatste

  18. Use of Peltier cells in high resolution alpha spectrometry

    International Nuclear Information System (INIS)

    Bueno, C.C.; Santos, M.D.S.; Goncalves, J.A.C.

    1994-01-01

    The experiments with low-cost commercial silicon PIN photodiodes have shown the possibility of their transformation for use as alpha detectors with performance comparable with surface barrier detectors which are more expensive. Utilizing the silicon photodiode with reverse bias, an energy resolution for 241 Am alpha particles of 28 KeV and 23 KeV were obtained at room temperature and at -30 0 C respectively. (author). 4 refs, 4 figs

  19. RAPID DETERMINATION OF 237 NP AND PU ISOTOPES IN WATER BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, S.; Jones, V.; Culligan, B.; Nichols, S.; Noyes, G.

    2010-06-23

    A new method that allows rapid preconcentration and separation of plutonium and neptunium in water samples was developed for the measurement of {sup 237}Np and Pu isotopes by inductively-coupled plasma mass spectrometry (ICP-MS) and alpha spectrometry; a hybrid approach. {sup 238}U can interfere with {sup 239}Pu measurement by ICP-MS as {sup 238}UH{sup +} mass overlap and {sup 237}Np via peak tailing. The method provide enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then moving Pu to DGA resin for additional removal of uranium. The decontamination factor for uranium from Pu is almost 100,000 and the decontamination factor for U from Np is greater than 10,000. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration is performed using a streamlined calcium phosphate precipitation method. Purified solutions are split between ICP-MS and alpha spectrometry so that long and short-lived Pu isotopes can be measured successfully. The method allows for simultaneous extraction of 20 samples (including QC samples) in 4 to 6 hours, and can also be used for emergency response. {sup 239}Pu, {sup 242}Pu and {sup 237}Np were measured by ICP-MS, while {sup 236}Pu, {sup 238}Pu, and {sup 239}Pu were measured by alpha spectrometry.

  20. Flow injection on-line dilution for multi-element determination in human urine with detection by inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Wang, Jianhua; Hansen, Elo Harald; Gammelgaard, Bente

    2001-01-01

    A simple flow injection on-line dilution procedure with detection by inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of copper, zinc, arsenic, lead, selenium, nickel and molybdenum in human urine. Matrix effects were minimized by employing a dilution factor...

  1. Cellular Lipid Extraction for Targeted Stable Isotope Dilution Liquid Chromatography-Mass Spectrometry Analysis

    Science.gov (United States)

    Gelhaus, Stacy L.; Mesaros, A. Clementina; Blair, Ian A.

    2011-01-01

    The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including numerous stereoisomers1,2. These metabolites can be formed from free or esterified fatty acids. Many of these oxidized metabolites have biological activity and have been implicated in various diseases including cardiovascular and neurodegenerative diseases, asthma, and cancer3-7. Oxidized bioactive lipids can be formed enzymatically or by reactive oxygen species (ROS). Enzymes that metabolize fatty acids include cyclooxygenase (COX), lipoxygenase (LO), and cytochromes P450 (CYPs)1,8. Enzymatic metabolism results in enantioselective formation whereas ROS oxidation results in the racemic formation of products. While this protocol focuses primarily on the analysis of AA- and some LA-derived bioactive metabolites; it could be easily applied to metabolites of other fatty acids. Bioactive lipids are extracted from cell lysate or media using liquid-liquid (l-l) extraction. At the beginning of the l-l extraction process, stable isotope internal standards are added to account for errors during sample preparation. Stable isotope dilution (SID) also accounts for any differences, such as ion suppression, that metabolites may experience during the mass spectrometry (MS) analysis9. After the extraction, derivatization with an electron capture (EC) reagent, pentafluorylbenzyl bromide (PFB) is employed to increase detection sensitivity10,11. Multiple reaction monitoring (MRM) is used to increase the selectivity of the MS analysis. Before MS analysis, lipids are separated using chiral normal phase high performance liquid chromatography (HPLC). The HPLC conditions are optimized to separate the enantiomers and various stereoisomers of the monitored lipids12. This specific LC-MS method monitors prostaglandins (PGs), isoprostanes (isoPs), hydroxyeicosatetraenoic acids (HETEs), hydroxyoctadecadienoic acids (HODEs), oxoeicosatetraenoic

  2. Improved sample preparation method for environmental plutonium analysis by ICP-SFMS and alpha-spectrometry

    International Nuclear Information System (INIS)

    Varga, Z.; Stefanka, Z.; Suranyi, G.; Vajda, N.

    2007-01-01

    A rapid and simple sample preparation method for plutonium determination in environmental samples by inductively coupled plasma sector field mass spectrometry (ICP-SFMS) and alpha-spectrometry is described. The developed procedure involves a selective CaF 2 co-precipitation for preconcentration followed by extraction chromatographic separation. The proposed method effectively eliminates the possible interferences in mass spectrometric analysis and also removes interfering radionuclides that may disturb alpha-spectrometric measurement. For 239 Pu, 240 Pu and 241 Pu limits of detection of 9.0 fg x g -1 (0.021 mBq), 1.7 fg x g -1 (0.014 mBq) and 3.1 fg x g -1 (11.9 mBq) were achieved by ICP-SFMS, respectively, and 0.02 mBq by alpha-spectrometry. Results of certified reference materials agreed well with the recommended values. (author)

  3. A simple source preparation method for alpha-ray spectrometry of volcanic rock sample

    International Nuclear Information System (INIS)

    Takahashi, Masaomi; Kurihara, Yuichi; Sato, Jun

    2006-01-01

    A simple source preparation method was developed for the alpha-ray spectrometry to determine U and Th in volcanic rockes. Isolation of U and Th from volcanic rocks was made by use of UTEVA-Spec. resin, extraction chromatograph material. U and Th were extracted by TTA-benzene solution and organic phase was evaporated drop by drop on a hot stainless steel planchet to dryness. This method was found to be effective for the preparation of sources for alpha-ray spectrometry. (author)

  4. Problems and progress in the preparation of sources for the alpha spectrometry of plutonium

    International Nuclear Information System (INIS)

    Miguel, M.; Deron, S.; Swietly, H.; Heinonen, O.J.

    1981-01-01

    The interpretation of non-destructive measurements of plutonium materials require more accurate determinations of the isotopic abundance of Pu-238 than conventional chemical assays. The requirements of calorimetry, passive neutron and conventional chemical assays are presented and compared. When Pu-238 is measured by alpha spectrometry, these requirements define how well the plutonium must be separated from americium, and what should be the accuracy of the spectrometry. The latter can strongly depend upon the resolution of the alpha spectrum. The authors describe a procedure to produce sources by drop deposition which ensure a resolution of 17 keV with commercial instrumentation

  5. Low-Temperature Positive Secondary Ion Mass Spectrometry of Neat and Argon-Diluted Organic Solids

    NARCIS (Netherlands)

    Jonkman, Harry T.; Michl, Josef; King, Robert N.; Andrade, Joseph D.

    1978-01-01

    Secondary ion mass spectrometry of neat solid propane, n-pentane, benzene, toluene, and of propane imbedded in an argon matrix were observed at temperatures varying from 10 to 110 K and show fragmentation patterns similar to those known from ordinary electron impact mass spectrometry. The effects of

  6. Precise determination of sodium in serum by simulated isotope dilution method of inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Yan Ying; Zhang Chuanbao; Zhao Haijian; Chen Wenxiang; Shen Ziyu; Wang Xiaoru; Chen Dengyun

    2007-01-01

    A new precise and accurate method for the determination of sodium in serum by inductively coupled plasma mass spectrometry (ICP-MS) was developed. Since 23 Na is the single isotope element, 27 Al is selected as simulated isotope of Na. Al is spiked into serum samples and Na standard solution. 23 Na/ 27 Al ratio in the Na standard solution is determined to assume the natural Na isotope ratio. The serums samples are digested by purified HNO 3 /H 2 O 2 and diluted to get about 0.6 μg·g -1 Al solutions, and the 23 Na/ 27 Al ratios of the serum samples are obtained to calculate the accurate Na concentrations basing on the isotope dilution method. When the simulated isotope dilution method of ICP-MS is applied and Al is selected as the simulated isotope of Na, the precise and accurate Na concentrations in the serums are determined. The inter-day precision of CV<0.13% for one same serum sample is obtained during 3 days 4 measurements. The spike recoveries are between 99.69% and 100.60% for 4 different serum samples and 3 days multi-measurements. The results of measuring standard reference materials of serum sodium are agree with the certified value. The relative difference between 3 days is 0.22%-0.65%, and the relative difference in one bottle is 0.15%-0.44%. The ICP-MS and Al simulated isotope dilution method is proved to be not only precise and accurate, but also quick and convenient for measuring Na in serum. It is promising to be a reference method for precise determination of Na in serum. Since Al is a low cost isotope dilution reagent, the method is possible to be widely applied for serum Na determination. (authors)

  7. Determination of Trace Iron in Red Wine by Isotope Dilution Mass Spectrometry Using Multiple-Collector Inductively Coupled Plasma Mass Spectrometry

    International Nuclear Information System (INIS)

    Zhou Tao; Wang Jun; Lu Hai; Zhou Yuanjing; Li Haifeng

    2009-01-01

    This paper introduces determination of trace iron in red wine certified reference material by isotope dilution mass spectrometry (IDMS) method using a multiplecollector inductively coupled plasma mass spectrometry, equipped with a hexapole collision cell. The measurement procedure of iron isotopic abundance ratios was deeply researched. Reduced polyatomic ion interferences to iron isotopes ion by collision reaction using Ar and H 2 gas, high precise isotopic abundance ratios were achieved. Two relative measurement methods (ICP-MS and ICP-OES) were used to analyze trace iron in red wine. The results are compared with IDMS results, which indicate that they are accordant. The uncertainty analyses include each uncertainty factor in whole experiment and the uncertainty of used certified reference material and it shows that the procedure blank is not neglectable to detect limit and precision of the method. The establishment of IDMS method for analysis of trace iron in red wine supports the certification of certified reference materials. (authors)

  8. Determination of Neptunium, Americium and Curium in Spent Nuclear Fuel Samples by Alpha Spectrometry Using 239Np and 243Am as a Spike and a Tracer

    International Nuclear Information System (INIS)

    Jeo, Kih-Soo; Song, Byung-Chul; Kim, Young-Bok; Han, Sun-Ho; Jeon, Young-Shin; Jung, Euo-Chang; Jee, Kwang-Yong

    2007-01-01

    Determination of actinide elements and fission products in spent nuclear fuels is of importance for a burnup determination and source term evaluation. Especially, the amounts of uranium and plutonium isotopes are used for the evaluation of a burnup credit in spent nuclear fuels. Additionally, other actinides such as Np, Am and Cm in spent nuclear fuel samples is also required for the purposes mentioned above. In this study, 237 Np, 241 Am and 244 Cm were determined by an alpha spectrometry for the source term data for high burnup spent nuclear fuels ranging from 37 to 62.9 GWD/MtU as a burnup. Generally, mass spectrometry has been known as the most powerful method for isotope determinations such as high concentrations of uranium and plutonium. However, in the case of minor actinides such as Np, Am and Cm, alpha spectrometry would be recommended instead. Determination of the transuranic elements in spent nuclear fuel samples is different from that for environmental samples because the amount of each nuclide in the spent fuel samples is higher and the relative ratios between each nuclide are also different from those for environmental samples. So, it is important to select an appropriate tracer and an optimum sample size depending on the nuclides and analytical method. In this study 237 Np was determined by an isotope dilution alpha(gamma) spectrometry using 239 Np as a spike, and 241 Am and curium isotopes were determined by alpha spectrometry using 243 Am as a tracer. The content of each nuclide was compared with that by the Origen-2 code

  9. Preparation of 237Np samples by electrodeposition and its determination by alpha spectrometry

    International Nuclear Information System (INIS)

    Mertzig, W.; Matsuda, H.T.; Araujo, B.F. de; Araujo, J.A. de

    1980-01-01

    An analytical method followed by alpha spectrometry was developed for the determination of trace amounts of actinides. A technique for quantitative electrodeposition of 237 Np, under optimal conditions, using a carrier, is presented. This method will be applied for the control of trace amounts of 237 Np in the solutions from the reprocessing (Purex process) of irradiated uranium. (C.L.B.) [pt

  10. Determination of ''226Ra by Alpha Spectrometry by Using ''225Ra as Yield Tracer

    International Nuclear Information System (INIS)

    Crespo, M. T.; Oller, O.

    1999-01-01

    A method for the determination of low-level ''226 Ra in environmental and geological samples by alpha spectrometry is described. The method is based on the use of ''225 Ra from ''229 Th as yield tracer and has been developed to analyze U, Th and Ra in the same sample. (Author) 12 refs

  11. An on-line dilution system for spectrometry using an inductively coupled plasma source

    International Nuclear Information System (INIS)

    Moore, G.L.; Watson, A.E.; Humphries-Cuff, P.J.

    1982-01-01

    An on-line dilution system that uses a two-channel peristaltic pump to feed a GMK Babington type of nebulizer is described. By the use of a diluent containing the appropriate concentrations of acid, sodium, and internal standard element, which was fed at a constant rate to the nebulizer, the system produced analytical results that are not significantly different (less than 3 per cent relative) from those obtained with the normal dilution technique. However, a considerable saving in time is achieved, as well as a saving in the use of expensive reagents

  12. Intercomparison of alpha and gamma spectrometry techniques used in (210)Pb geochronology.

    Science.gov (United States)

    Zaborska, Agata; Carroll, Jolynn; Papucci, Carlo; Pempkowiak, Janusz

    2007-01-01

    (210)Pb geochronology is a widely used tool in sedimentological studies aimed at the absolute ages of modern sediments (up to 100 years). (210)Pb activities required to model sedimentation regimes are measured using either alpha, gamma or beta spectrometry. Sediment accumulation rates derived from (210)Pb activity profiles measured by these methods are often used interchangeably in mass balance studies. Yet there is a lack of investigations considering the comparability of data derived using different analytical methods. Differences between methods could be caused by different behaviors of (210)Pb and (210)Po (used for alpha measurement) in the marine environment. In gamma spectrometry errors may arise when many gamma emitters are measured simultaneously and their activity peaks overlap. In alpha spectrometry chemical separation of (210)Po may result in analytical error due to incomplete sample dissolution. In the present study we evaluate total, supported and excess (210)Pb activities and their use in deriving sediment accumulation rates and (210)Pb excess inventories for three sediment cores collected from the Barents Sea. (210)Pb activities derived by alpha and gamma methods are shown to agree within counting error and there is also good agreement in the derived sediment accumulation rates. The inherent compatibility of analytical results based on alpha or gamma techniques is established.

  13. Ultra-high-resolution alpha spectrometry for nuclear forensics and safeguards applications

    International Nuclear Information System (INIS)

    Bacrania, Minesh K.; Croce, Mark; Bond, Evelyn; Dry, Donald; Moody, W. Allen; Lamont, Stephen; Rabin, Michael; Rim, Jung; Smith, Audrey; Beall, James; Bennett, Douglas; Kotsubo, Vincent; Horansky, Robert; Hilton, Gene; Schmidt, Daniel; Ullom, Joel; Cantor, Robin

    2010-01-01

    We will present our work on the development of ultra-high-resolution detectors for alpha particle spectrometry. These detectors, based on superconducting transition-edge sensors, offer energy resolution that is five to ten times better than conventional silicon detectors. Using these microcalorimeter detectors, the isotopic composition of mixed-actinide samples can be determined rapidly without the need for actinide separation chemistry to isolate each element, or mass spectrometry to separate isotopic signatures that can not be resolved using traditional alpha spectrometry (e.g. Pu-239/Pu-240, or Pu-238/Am-241). This paper will cover the detector and measurement system, actinide source preparation, and the quantitative isotopic analysis of a number of forensics- and safeguards-relevant radioactive sources.

  14. Determination of Uranium plus Plutonium by Alpha spectrometry in different matrix

    International Nuclear Information System (INIS)

    Equillor, Hugo E.; Campos, Juan M.

    2011-01-01

    Usually, the determination of alpha emitters by alpha spectrometry is performed with a prior purification of each of the elements to be quantified. In this work, a methodology for the determination of uranium and plutonium isotopes as jointly described, in order to improve analytical processing times and measurement. The method includes purifying uranium and plutonium, and the subsequent electrodeposition for alpha spectrometry measurement. The technique is based on the use of TBP (tributyl phosphate) as extractant and easy to obtain reactants. It is applicable to various matrices, including water, filters and soils. In the conditions described, is applied to small aliquots of approximately 0.5 g of solid. The technique produces high quality electrodeposits. (authors) [es

  15. Characterization of high level waste for minor actinides by chemical separation and alpha spectrometry

    International Nuclear Information System (INIS)

    Murali, M.S.; Bhattacharayya, A.; Kar, A.S.; Tomar, B.S.; Manchanda, V.K.

    2010-01-01

    Quantification of minor actinides present in of High Level Waste (HLW) solutions originating from the power reactors is important in view of management of radioactive wastes and actinide partitioning. Several methods such as ICP-MS, X-ray fluorescence methods, ICP-AES, alpha spectrometry are used in characterizing such types of wastes. As alpha spectrometry is simple and reliable, this technique has been used for the estimation of minor actinides after devising steps of separation for estimating Np and Pu present in HLW solutions of PHWR origin. Using a wealth of knowledge appropriate to the solution chemistry of actinides, the task of separation, though appears easy, it is challenging job for a radiochemist handling high-dose HLW samples, for obtaining clean alpha peaks for Np and Pu. This paper reports on the successful attempt made to quantify 241 Am, 244 Cm, Pu (239 mainly) and 237 Np present in HLW-PHWR obtained from PREFRE, Tarapur

  16. Online Measurement of Exhaled NO Concentration and Its Production Sites by Fast Non-equilibrium Dilution Ion Mobility Spectrometry

    Science.gov (United States)

    Peng, Liying; Jiang, Dandan; Wang, Zhenxin; Liu, Jiwei; Li, Haiyang

    2016-03-01

    Exhaled nitric oxide (NO) is one of the most promising breath markers for respiratory diseases. Its profile for exhalation and the respiratory NO production sites can provide useful information for medical disease diagnosis and therapeutic procedures. However, the high-level moisture in exhaled gas always leads to the poor selectivity and sensitivity for ion spectrometric techniques. Herein, a method based on fast non-equilibrium dilution ion mobility spectrometry (NED-IMS) was firstly proposed to directly monitor the exhaled NO profile on line. The moisture interference was eliminated by turbulently diluting the original moisture to 21% of the original with the drift gas and dilution gas. Weak enhancement was observed for humid NO response and its limit of detection at 100% relative humidity was down to 0.58 ppb. The NO concentrations at multiple exhalation flow rates were measured, while its respiratory production sites were determined by using two-compartment model (2CM) and Högman and Meriläinen algorithm (HMA). Last but not the least, the NO production sites were analyzed hourly to tentatively investigate the daily physiological process of NO. The results demonstrated the capacity of NED-IMS in the real-time analysis of exhaled NO and its production sites for clinical diagnosis and assessment.

  17. Direct quantification of creatinine in human urine by using isotope dilution extractive electrospray ionization tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Li Xue [Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, Applied Chemistry Department, East China Institute of Technology, Nanchang 330013 (China); Fang Xiaowei [Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, Applied Chemistry Department, East China Institute of Technology, Nanchang 330013 (China); Yu Zhiqiang; Sheng Guoying [Guangdong Key Laboratory of Environmental Protection and Resource Utilization, State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Wu Minghong [Shanghai Applied Radiation Institute, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Fu Jiamo [Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Guangdong Key Laboratory of Environmental Protection and Resource Utilization, State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Chen Huanwen, E-mail: chw8868@gmail.com [Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, Applied Chemistry Department, East China Institute of Technology, Nanchang 330013 (China)

    2012-10-20

    Highlights: Black-Right-Pointing-Pointer High throughput analysis of urinary creatinine is achieved by using ID-EESI-MS/MS. Black-Right-Pointing-Pointer Urine sample is directly analyzed and no sample pre-treatment is required. Black-Right-Pointing-Pointer Accurate quantification is accomplished with isotope dilution technique. - Abstract: Urinary creatinine (CRE) is an important biomarker of renal function. Fast and accurate quantification of CRE in human urine is required by clinical research. By using isotope dilution extractive electrospray ionization tandem mass spectrometry (EESI-MS/MS) a high throughput method for direct and accurate quantification of urinary CRE was developed in this study. Under optimized conditions, the method detection limit was lower than 50 {mu}g L{sup -1}. Over the concentration range investigated (0.05-10 mg L{sup -1}), the calibration curve was obtained with satisfactory linearity (R{sup 2} = 0.9861), and the relative standard deviation (RSD) values for CRE and isotope-labeled CRE (CRE-d3) were 7.1-11.8% (n = 6) and 4.1-11.3% (n = 6), respectively. The isotope dilution EESI-MS/MS method was validated by analyzing six human urine samples, and the results were comparable with the conventional spectrophotometric method (based on the Jaffe reaction). Recoveries for individual urine samples were 85-111% and less than 0.3 min was taken for each measurement, indicating that the present isotope dilution EESI-MS/MS method is a promising strategy for the fast and accurate quantification of urinary CRE in clinical laboratories.

  18. Determination of {sup 227}Ac by {alpha}-particle spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Martin, P. [Environmental Research Inst. of the Supervising Scientist, Jabiru, NT (Australia); Hancock, G.J. [Commonwealth Scientific and Industrial Research Organization, Canberra, ACT (Australia). Div. of Water Resources; Paulka, S. [Australian Radiation Lab., Yallambie, VIC (Australia); Akber, R.A. [Queensland Univ. of Technology, Brisbane, QLD (Australia)

    1995-10-01

    A method is described for the determination of {sup 227}Ac concentration in environmental samples. Actinium is separated from the sample digest by co-precipitation with lead sulphate, purified using anion and cation exchange techniques, and electrodeposited onto a stainless-steel disc. The chemical yield is monitored by addition of a {sup 229}Th/{sup 225}Ra/{sup 225}Ac tracer before sample dissolution. {sup 225}Ac recovery is determined from an initial count by measurement of its {alpha}-emitting daughter, {sup 217}At. The disc is then stored for 2-3 months and recounted. The {sup 227}Ac activity is obtained by measurement of the ingrown {sup 227}Th and {sup 223}Ra activities in the 5.38-6.10 MeV region. Co-precipitation with lead sulphate enables the convenient determination of actinium, thorium and radium on the same sample digest. (author).

  19. Radiometric dating by alpha spectrometry on uranium series nuclides

    International Nuclear Information System (INIS)

    Wijk, A. van der.

    1987-01-01

    This thesis describes the analytical and technical procedures that are required for routine application of both the 230 Th/ 234 U disequilibrium dating method for peat and the 210 Pb dating method for lake sediments. Its principal aim is to test, refine and discuss the reliability and validity of these methods. On the other hand, the analytical procedures that were introduced open a wide range of other interesting fields of research that are not necessarily restricted to geological problems only. Chapter 5 reports an obviously not foreseen application: detection of alpha emitting nuclides released in the first weeks of May, 1986 during the accident with the nuclear power plant in Chernobyl, USSR. 128 refs.; 43 figs.; 15 tabs

  20. Urinary detection of conjugated and unconjugated anabolic steroids by dilute-and-shoot liquid chromatography-high resolution mass spectrometry.

    Science.gov (United States)

    Tudela, Eva; Deventer, Koen; Geldof, Lore; Van Eenoo, Peter

    2015-02-01

    Anabolic androgenic steroids (AAS) are an important class of doping agents. The metabolism of these substances is generally very extensive and includes phase-I and phase-II pathways. In this work, a comprehensive detection of these metabolites is described using a 2-fold dilution of urine and subsequent analysis by liquid chromatography-high resolution mass spectrometry (LC-HRMS). The method was applied to study 32 different metabolites, excreted free or conjugated (glucuronide or sulfate), which permit the detection of misuse of at least 21 anabolic steroids. The method has been fully validated for 21 target compounds (8 glucuronide, 1 sulfate and 12 free steroids) and 18 out of 21 compounds had detection limits in the range of 1-10 ng mL(-1) in urine. For the conjugated compounds, for which no reference standards are available, metabolites were synthesized in vitro or excretion studies were investigated. The detection limits for these compounds ranged between 0.5 and 18 ng mL(-1) in urine. The simple and straightforward methodology complements the traditional methods based on hydrolysis, liquid-liquid extraction, derivatization and analysis by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). Copyright © 2014 John Wiley & Sons, Ltd.

  1. Application of PERALS™ alpha spectrometry and gamma spectrometry for analysis and investigation of environmental spills at ISL uranium mining projects.

    Science.gov (United States)

    Borysenko, A; Ostrowski, A; Bellifemine, D; Palmer, G; Haigh, P; Johnston, A

    2014-03-01

    Radiation protection and environmental monitoring in mining requires effective and reliable radionuclide analysis at all stages of the mine project-prior to mining, during operation and through to remediation and decommissioning. The approach presented in this paper was specially developed for the monitoring of radioactive waste resulting from spills during mining and mineral processing operations and uses a combination of high resolution gamma spectrometry, and PERALS™ alpha spectrometry to identify and reliably quantify the activity of the major members of the U-238 decay chain at activities down to 10 mBq g(-1) by direct radionuclide counting and by assessment of the activity of their decay products. This approach has reduced sample preparation and analysis time while providing effective analysis and quantification of naturally occurring radionuclides in environmental samples. It has been successfully applied to several in situ leach (ISL) mining-related projects involving investigations of process material spill impacts and also to routine environmental monitoring.

  2. Determination of Uranium, Thorium and Radium 226 in Zircon containig sands by alpha spectrometry

    International Nuclear Information System (INIS)

    Spezzano, P.

    1985-01-01

    The industrial utilization of Zircon sands for the production of refractories presents radiological problems owing to the risk of inhalation of Uranium, Thorium and their decay products, present in high concentrations in such materials. A method of analysis was realized for the determination of Uranium, Thorium and Radium-226 in Zircon sands, including the total dissolution of the sample, radiochemical separation and final measurement by alpha spectrometry with surface barrier detector. The concentrations of the main alpha-emitting radionuclides presents in two samples of Zircon sands have been determined and the possibility of disequilibrium along the decay series has been pointed out

  3. Alpha spectrometry of thick sources. I. Application to alpha emitters determination

    International Nuclear Information System (INIS)

    Acena, M.L.; Garcia-Torano, E.; Rivero, M.C.

    1977-01-01

    A method for determining alpha emitters by silicon surface barrier detector spectroscopy using thick sources is studied. Two types of spectra have been obtained. They have different shapes of line according to the procedure used for preparing the sources. For both spectra a computing least square programme has been developed. In this way it is possible to calculate line intensities with accuracy better than 20 percent. (author) [es

  4. Determination of thyroid hormones in placenta using isotope-dilution liquid chromatography quadrupole time-of-flight mass spectrometry

    DEFF Research Database (Denmark)

    Li, Zhong-Min; Giesert, Florian; Vogt-Weisenhorn, Daniela

    2018-01-01

    (13C6-T4, 13C6-T3, 13C6-rT3 and 13C6-T2) and recovery standard (13C12-T4) in combination with solid-liquid extraction, liquid-liquid extraction and solid phase extraction. The linearity was obtained in the range of 0.5-150 pg uL-1 with R2 values >0.99. The method detection limits (MDLs) ranged from 0......-l-thyronine (rT3), 3,3'-diiodo-l-thyronine (T2), 3,5-diiodo-l-thyronine (rT2), 3-iodo-l-thyronine (T1) and 3-iodothyronamine (T1AM), in placenta using isotope dilution liquid chromatography quadrupole time-of-flight mass spectrometry. We optimized the method using isotopically labeled quantification standards...

  5. Quantitative Measurement of Intact Alpha-Synuclein Proteoforms from Post-Mortem Control and Parkinson's Disease Brain Tissue by Intact Protein Mass Spectrometry

    Science.gov (United States)

    Kellie, John F.; Higgs, Richard E.; Ryder, John W.; Major, Anthony; Beach, Thomas G.; Adler, Charles H.; Merchant, Kalpana; Knierman, Michael D.

    2014-07-01

    A robust top down proteomics method is presented for profiling alpha-synuclein species from autopsied human frontal cortex brain tissue from Parkinson's cases and controls. The method was used to test the hypothesis that pathology associated brain tissue will have a different profile of post-translationally modified alpha-synuclein than the control samples. Validation of the sample processing steps, mass spectrometry based measurements, and data processing steps were performed. The intact protein quantitation method features extraction and integration of m/z data from each charge state of a detected alpha-synuclein species and fitting of the data to a simple linear model which accounts for concentration and charge state variability. The quantitation method was validated with serial dilutions of intact protein standards. Using the method on the human brain samples, several previously unreported modifications in alpha-synuclein were identified. Low levels of phosphorylated alpha synuclein were detected in brain tissue fractions enriched for Lewy body pathology and were marginally significant between PD cases and controls (p = 0.03).

  6. Proceedings of the International Symposium Advances in alpha, Beta- and Gamma-Ray spectrometry

    International Nuclear Information System (INIS)

    1997-01-01

    The International Committee for Radionuclide Metrology (ICRM) is an association of radionuclide metrology laboratories whose membership is composed of delegates of these laboratories together with other scientists actively engaged in the study and applications of radioactivity. The scientific activities are carried out in the frame of six Working Groups. Two of them, the Alpha-Particle Spectrometry and the Gamma-and Beta-ray Spectrometry Working Groups held a common workshop in Pushkin, St. Petersburg, 18 to 20 September 1996, under the title Advances in Alpha-Beta-and Gamma-Ray Sepectrometry, at the kind invitation of the D.I. Mendeleyev Institute for Metrology. More than 30 people from 14 laboratories attended the meeting, and nineteen oral communications were presented, from which twelve were retained for publication an are included in these proceedings. (Author)

  7. Standard test method for 238Pu isotopic abundance by alpha spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2001-01-01

    1.1 This test method covers the use of alpha spectrometry for determining the 238Pu isotopic abundance in plutonium samples. It is particularly useful for samples in which the 238Pu content is less than 1 % of the total plutonium content. For such samples, mass spectrometric results are less reliable than those from alpha spectrometry because of interference from any 238U isobar remaining after ion exchange. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  8. Determination of the interchangeable heavy-metal fraction in soils by isotope dilution mass spectrometry

    International Nuclear Information System (INIS)

    Gaebler, H.E.; Bahr, A.; Mieke, B.

    1999-01-01

    An isotope dilution technique using enriched stable isotopes is applied to determine the interchangeable heavy-metal fraction in soils. Metals in two soil samples are extracted at constant pH, with water, NH 4 NO 3 , and EDTA. A spike of enriched stable isotopes is added to the suspension of sample and eluant at the beginning of the extraction. The heavy-metal fraction which exchanges with the added spike during the extraction is called the interchangeable fraction. The extractable heavy-metal fractions are obtained from the heavy-metal concentrations in the eluates. Isotope ratios and concentrations are determined by HR-ICP-MS. The isotope dilution technique described enables both the extractable and the interchangeable heavy-metal fractions to be determined in the same experiment. The combination of both results gives additional information on elemental availability under different conditions that cannot be obtained by analyzing the extractable heavy-metal fractions alone. It is demonstrated that in some cases different eluants just shift the distribution of the interchangeable fraction of an element between the solid and liquid phases (e.g., Pb and Cd in a topsoil sample) while the amount of the interchangeable fraction itself remains constant. For other elements, as Ni, Zn, and Cr, the use of different eluants (different pH, complexing agents) sometimes enlarges the interchangeable fraction. (orig.)

  9. Direct determination of mercury in cosmetic samples by isotope dilution inductively coupled plasma mass spectrometry after dissolution with formic acid

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Ying; Shi, Zeming; Zong, Qinxia; Wu, Peng; Su, Jing [Sichuan Provincial Key Laboratory of Nuclear Technology in Geology, College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu 610059 (China); Liu, Rui, E-mail: liur.ray@gmail.com [Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institutions, College of Materials and Chemistry and Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China)

    2014-02-17

    Graphical abstract: -- Highlights: •Simple, sensitive, and accurate method is established for mercury determination in cosmetics. •The sample preparation procedure is highly simplified. •Isotope dilution efficiently eliminates matrix effect. •First report of using formic acid based method in combination with PVG-ID-ICP MS for mercury quantitation in cosmetics. -- Abstract: A new method was proposed for the accurate determination of mercury in cosmetic samples based on isotopic dilution (ID)-photochemical vapor generation (PVG)-inductively coupled plasma mass spectrometry (ICP MS) measurement. Cosmetic samples were directly dissolved in formic acid solution and subsequently subjected to PVG for the reduction of mercury into vapor species following by ICP MS detection. Therefore, the risks of analyte contamination and loss were avoided. Highly enriched {sup 201}Hg isotopic spike is added to cosmetics and the isotope ratios of {sup 201}Hg/{sup 202}Hg were measured for the quantitation of mercury. With ID calibration, the influences originating from sample matrixes for the determination of mercury in cosmetic samples have been efficiently eliminated. The effects of several experimental parameters, such as the concentration of the formic acid, and the flow rates of carrier gas and sample were investigated. The method provided good reproducibility and the detection limits were found to be 0.6 pg mL{sup −1}. Finally, the developed method was successfully applied for the determination of mercury in six cosmetic samples and a spike test was performed to verify the accuracy of the method.

  10. Direct determination of mercury in cosmetic samples by isotope dilution inductively coupled plasma mass spectrometry after dissolution with formic acid

    International Nuclear Information System (INIS)

    Gao, Ying; Shi, Zeming; Zong, Qinxia; Wu, Peng; Su, Jing; Liu, Rui

    2014-01-01

    Graphical abstract: -- Highlights: •Simple, sensitive, and accurate method is established for mercury determination in cosmetics. •The sample preparation procedure is highly simplified. •Isotope dilution efficiently eliminates matrix effect. •First report of using formic acid based method in combination with PVG-ID-ICP MS for mercury quantitation in cosmetics. -- Abstract: A new method was proposed for the accurate determination of mercury in cosmetic samples based on isotopic dilution (ID)-photochemical vapor generation (PVG)-inductively coupled plasma mass spectrometry (ICP MS) measurement. Cosmetic samples were directly dissolved in formic acid solution and subsequently subjected to PVG for the reduction of mercury into vapor species following by ICP MS detection. Therefore, the risks of analyte contamination and loss were avoided. Highly enriched 201 Hg isotopic spike is added to cosmetics and the isotope ratios of 201 Hg/ 202 Hg were measured for the quantitation of mercury. With ID calibration, the influences originating from sample matrixes for the determination of mercury in cosmetic samples have been efficiently eliminated. The effects of several experimental parameters, such as the concentration of the formic acid, and the flow rates of carrier gas and sample were investigated. The method provided good reproducibility and the detection limits were found to be 0.6 pg mL −1 . Finally, the developed method was successfully applied for the determination of mercury in six cosmetic samples and a spike test was performed to verify the accuracy of the method

  11. Alpha spectrometry of thick sources. II. Application to the study of radioactive equilibria in uranium ores

    International Nuclear Information System (INIS)

    Acena Barrenechea, M.L.; Tormo Ferrero, M.J.

    1977-01-01

    A method for determining nuclide activities in 4n + 2 uranium series using alpha spectrometry of thick sources is described. This method has been applied to several uranium ores, showing different states of radioactive equilibria. The spectra from samples prepared by cold compression show some anomalies, due to the evolution and later decay of 219 Rn and daughters. This phenomenon must be taken in consideration when computing spectra line intensities. (author) [es

  12. Cryogenic microcalorimeter system for ultra-high resolution alpha-particle spectrometry

    International Nuclear Information System (INIS)

    Rabin, Michael W.; Hoover, Andrew S.; Bacrania, Minesh K.; Croce, Mark P.; Hoteling, N.J.; Lamont, S.P.; Plionis, A.A.; Dry, D.E.; Ullom, J.N.; Bennett, D.A.; Horansky, R.; Kotsubo, V.; Cantor, R.

    2009-01-01

    Microcalorimeters have been shown to yield unsurpassed energy resolution for alpha spectrometry, up to 1.06 keV FWHM at 5.3 MeV. These detectors use a superconducting transition-edge sensor (TES) to measure the temperature change in an absorber from energy deposited by an interacting alpha particle. Our system has four independent detectors mounted inside a liquid nitrogen/liquid helium cryostat. An adiabatic demagnetization refrigerator (ADR) cools the detector stage to its operating temperature of 80 mK. Temperature regulation with ∼15 uK peak-to-peak variation is achieved by PID control of the ADR. The detectors are voltage-biased, and the current signal is amplified by a commercial SQUID readout system and digitized for further analysis, This paper will discuss design and operation of our microcalorimeter alpha spectrometer, and will show recent results.

  13. A new method for the determination of NO2 traces using isotope dilution and mass spectrometry analysis

    International Nuclear Information System (INIS)

    Stevens, C.; Barat, F.; Nguyen Nghi, H.

    1975-01-01

    A new method for the determination of NO 2 traces, in the order of 1ppb (10 -9 ), in atmosphere and stratosphere is described. The method consists in an isotope dilution technique using 15 NO 2 , followed by the reduction of NO 2 to N 2 and a mass spectrometry analysis. A known amount of 15 NO 2 is added to the air samples. Then, NO 2 is separated from H 2 O, HNO 3 , CO 2 and N 2 O and transferred to a SiO 2 reactor by trapping at -196 deg C. In the reactor NO 2 is reduced to N 2 by reaction with electrolytic Cu heated at 580 deg C. The mass 29/mass 30 ratio corresponding to 15 N 14 N and 15 N 15 N is determined by mass spectrometry. The sensitivity of the method depends on the contamination introduced during the analysis of the sample (reagents, separation and measuring devices). The contamination is reproducible and in the order of 4.5+-0.5 10 -2 mm 3 N 2 [fr

  14. Formic acid hydrolysis/liquid chromatography isotope dilution mass spectrometry: An accurate method for large DNA quantification.

    Science.gov (United States)

    Shibayama, Sachie; Fujii, Shin-Ichiro; Inagaki, Kazumi; Yamazaki, Taichi; Takatsu, Akiko

    2016-10-14

    Liquid chromatography-isotope dilution mass spectrometry (LC-IDMS) with formic acid hydrolysis was established for the accurate quantification of λDNA. The over-decomposition of nucleobases in formic acid hydrolysis was restricted by optimizing the reaction temperature and the reaction time, and accurately corrected by using deoxynucleotides (dNMPs) and isotope-labeled dNMPs as the calibrator and the internal standard, respectively. The present method could quantify λDNA with an expanded uncertainty of 4.6% using 10fmol of λDNA. The analytical results obtained with the present method were validated by comparing with the results of phosphate-base quantification by inductively coupled plasma-mass spectrometry (ICP-MS). The results showed good agreement with each other. We conclude that the formic acid hydrolysis/LC-IDMS method can quantify λDNA accurately and is promising as the primary method for the certification of DNA as reference material. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Determination of copper in uniformly-doped silicon thin film by isotope-dilution inductively coupled plasma mass spectrometry

    CERN Document Server

    Park, C J; Lee, D S

    2001-01-01

    Uniformly-doped silicon thin films were fabricated by ion beam sputter deposition. The thin films had four levels of copper dopant concentration ranging between 1 x 10 sup 1 sup 9 and 1 x 10 sup 2 sup 1 atoms/cm sup 3. Concentrations of Copper dopants were determined by the isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) to provide certified reference data for the quantitative surface analysis by secondary ion mass spectrometry (SIMS). The copper-doped thin films were dissolved in a mixture of 1 M HF and 3 M HNO sub 3 spiked with appropriate amounts of sup 6 sup 5 Cu. For an accurate isotope ratio determination, both the detector dead time and the mass discrimination were appropriately corrected and isobaric interference from SiAr molecular ions was avoided by a careful sample pretreatment. An analyte recovery efficiency was obtained for the Cu spiked samples to evaluate accuracy of the method. Uncertainty of the determined copper concentrations, estimated following the EURACHEM Guide, ...

  16. Precise determination of dissolved silica in seawater by ion-exclusion chromatography isotope dilution inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Nonose, Naoko; Cheong, Chikako; Ishizawa, Yukari; Miura, Tsutomu; Hioki, Akiharu

    2014-08-20

    Ion exclusion chromatograph (IEC) isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP-MS) (IEC-ID-ICP-MS) was developed for measurement of dissolved silica in seawater, which was applied to production of certified reference materials (CRMs) of three concentration levels of nutrients (high, medium and low levels). IEC-ICP-MS has been employed to separate dissolved silica from seawater matrix. In the present study, in order to solve substantial problems due to spectral interference in ICP-MS and to improve the accuracy of IEC-ICP-MS beyond standard addition or conventional calibration methods, ID method was coupled with ICP-sector field mass spectrometry (operated under medium resolution,i.e., m/Δm=4000). In addition, effects of various operating parameters in ICP-MS on a silicon background level were also investigated to obtain lower background equivalent concentration (BEC). As a result, 3 ng g(-1) of the BEC and 0.5 % of relative standard uncertainties were achieved in the analyses of dissolved silica in seawater samples at concentration levels from 4.0 mg kg (-1) to 0.8 mg kg(-1) as silicon. The developed method was successfully validated by analyses of an artificial seawater containing a known amount of silicate and the seawater certified reference material MOOS-2 produced by the National Research Council Canada. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Evaluation of online carbon isotope dilution mass spectrometry for the purity assessment of synthetic peptide standards.

    Science.gov (United States)

    Cueto Díaz, Sergio; Ruiz Encinar, Jorge; García Alonso, J Ignacio

    2014-09-24

    We present a novel method for the purity assessment of peptide standards which is applicable to any water soluble peptide. The method is based on the online (13)C isotope dilution approach in which the peptide is separated from its related impurities by liquid chromatography (LC) and the eluent is mixed post-column with a continuous flow of (13)C-enriched sodium bicarbonate. An online oxidation step using sodium persulfate in acidic media at 99°C provides quantitative oxidation to (12)CO2 and (13)CO2 respectively which is extracted to a gaseous phase with the help of a gas permeable membrane. The measurement of the isotope ratio 44/45 in the mass spectrometer allows the construction of the mass flow chromatogram. As the only species that is finally measured in the mass spectrometer is CO2, the peptide content in the standard can be quantified, on the base of its carbon content, using a generic primary standard such as potassium hydrogen phthalate. The approach was validated by the analysis of a reference material (NIST 8327), and applied to the quantification of two commercial synthetic peptide standards. In that case, the results obtained were compared with those obtained using alternative methods, such as amino acid analysis and ICP-MS. The results obtained proved the value of the method for the fast, accurate and precise mass purity assignment of synthetic peptide standards. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Factors affecting the energy resolution in alpha particle spectrometry with silicon diodes

    International Nuclear Information System (INIS)

    Camargo, Fabio de.

    2005-01-01

    In this work are presented the studies about the response of a multi-structure guard rings silicon diode for detection and spectrometry of alpha particles. This ion-implanted diode (Al/p + /n/n + /Al) was processed out of 300 μm thick, n type substrate with a resistivity of 3 kΩ·cm and an active area of 4 mm 2 . In order to use this diode as a detector, the bias voltage was applied on the n + side, the first guard ring was grounded and the electrical signals were readout from the p + side. These signals were directly sent to a tailor made preamplifier, based on the hybrid circuit A250 (Amptek), followed by a conventional nuclear electronic. The results obtained with this system for the direct detection of alpha particles from 241 Am showed an excellent response stability with a high detection efficiency (≅ 100 %). The performance of this diode for alpha particle spectrometry was studied and it was prioritized the influence of the polarization voltage, the electronic noise, the temperature and the source-diode distance on the energy resolution. The results showed that the major contribution for the deterioration of this parameter is due to the diode dead layer thickness (1 μm). However, even at room temperature, the energy resolution (FWHM = 18.8 keV) measured for the 5485.6 MeV alpha particles ( 241 Am) is comparable to those obtained with ordinary silicon barrier detectors frequently used for these particles spectrometry. (author)

  19. Quantitative determination of cyclobutane thymine dimers in DNA by stable isotope-dilution mass spectrometry

    International Nuclear Information System (INIS)

    Podmore, I.D.; Cooke, M.S.; Herbert, K.E.; Lunec, J.

    1996-01-01

    In order to understand the role of UV-induced DNA lesions in biological processes such as mutagenesis and carcinogenesis, it is essential to detect and quantify DNA damage in cells. In this paper we present a novel and both highly selective and sensitive assay using capillary gas chromatography (GC) combined with mass spectrometry (MS) for the detection and accurate quantitation of a major product of UV-induced DNA damage (cis-syb cyclobutadithymine). Quantitation of the cyclobutane thymine dimer was achieved by the use of an internal standard in the form of a stable 2 H-labeled analogue. Both isotopically labeled and nonlabeled dimers were prepared directly from their corresponding monomers. Each was identified as their trimethylsilyl ether derivative by GC-MS. Calibration plots were obtained for known quantities of both nonlabeled and analyte and internal standard. Quantitation of cis-syn cyclobutadithymine was demonstrated in DNA exposed to UVC radiation over a dose range of 0 3500 J m -2 . Under the conditions used, the limit of detection was found to be 20-50 fmol on column (equivalent to 0.002-0.005 nmol dimer per mg DNA). The results of the present study indicate that capillary GC-MS is an ideally suited technique for selective and sensitive quantification of cis-syn cyclobutadithymine in DNA and hence UV-induced DNA damage. (author)

  20. Direct measurement of burn up monitor by Pulsed Laser Deposition (PLD) followed by Isotopic Dilution Mass Spectrometry

    International Nuclear Information System (INIS)

    Sajimol, R.; Manoravi, P.; NaIini, S.; Balasubramanian, R.; Joseph, M.

    2012-01-01

    Burn-up measurement is an important aspect in the assessment of fuel performance especially for experimental nuclear fuels. Conventional mass spectrometric technique offer the best accuracy for determination of burn-up but they suffer from the labour intensive and time consuming chemical separation procedures followed by mass spectrometric analysis. Our laboratory has reported a potential laser mass spectrometric technique with advantages of (i) direct and fast measurement of ion intensities of selected rare earth element and residual heavy element atoms to deduce burn up and (ii) adaptability to remote handling of radioactive samples. Direct quantification of burn up monitor element in fuel in the form of pellet as well as liquid was probed by pulsed laser deposition followed by Isotopic Dilution Mass Spectrometric technique (IDMS). The procedure involving laser ablation of heavy element (namely U and Pu) and fission product (Nd, La etc) from a simulated spent fuel matrix followed by isotopic dilution mass spectrometry using thermal ionization mass spectrometry (TIMS) has been presently attempted to arrive at the rare earth element to heavy element ratio to deduce burn up using the methodology described in our earlier work. The details of IDMS technique has been reviewed by Heumann et al. Accurately weighed amounts of major rare earth fission products such as Nd, La, Ce and Sm in solution form were mixed with known quantity of uranium solution (all the weights are corresponding to their fission yields and the residual heavy element atoms after a given burn up) and mixed together to attain uniformity. The solution is then dried and resulting powder was pelletized and sintered. Subsequently, the pellet was ablated with pulsed laser (8 ns, 532 nm, Nd-YAG) and the plume was deposited on a glass plate. This deposit was dissolved in minimum amount of nitric acid. A known volume of the solution was mixed with spike (for e.g., 150 Nd/ 142 Nd, 233 U/ 238 U in this study

  1. Certification measurement of the cadmium, copper and lead contents in rice using isotope dilution inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Vassileva, Emilia; Quetel, Christophe R.

    2004-01-01

    This paper describes the certification of the Cd, Cu and Pb amount contents in a rice material, that were used as reference values for round 19 of the international measurement evaluation programme (IMEP). The protocol developed in this study was based on isotope dilution associated to inductively coupled plasma mass spectrometry (ID-ICP-MS). A multiple spiking approach was applied to reduce significantly the number of analytical steps. For the decomposition of the sample, three different microwave assisted digestion procedures were tested and compared. The use of hydrofluoric acid was found necessary to ensure full solubilisation and complete isotopic equilibration. Estimation of the combined uncertainty attached to the measurement results was performed according to the ISO guidelines. Contributions from the correction for moisture content, sample homogeneity, procedural blank, spike impurities, spectral interferences, instrumental background and dead-time effects were evaluated. SI-traceable values with less than 2% combined uncertainty (k = 2) were obtained for Cd, Cu and Pb, respectively, (14.39 ± 0.21) x 10 -6 mol kg -1 , (44.31 ± 0.42) x 10 -6 mol kg -1 and (2.034 ± 0.034) x 10 -6 mol kg -1 . The rice powder was observed to be highly hygroscopic and a second series of isotope dilution mass spectrometry measurements was carried out on samples in equilibrium with the ambient moisture conditions ('saturated' samples). The Comite Consultatif pour la Quantite de Matiere (CCQM) requested this approach for the participation to the key comparison 24 on the same rice test material. The excellent agreement for Cd between the IMEP-19 reference value, the value submitted by the institute for reference materials and measurements (IRMM) to CCQM-K24 and the corresponding reference value obtained as the arithmetic mean from the results of the 11 participating National Measurement Institutes (less than 0.27% difference) further validated this work. Eventually, this series

  2. Gestodene and desogestrel do not have a different influence on concentration profiles of ethinylestradiol in women taking oral contraceptives--results of isotope dilution mass spectrometry measurements.

    Science.gov (United States)

    Siekmann, L; Siekmann, A; Bidlingmaier, F; Brill, K; Albring, M

    1998-08-01

    A new method for the quantitative determination of 17alpha-ethinylestradiol-17beta (EE2) in serum is presented here based on the principle of isotope dilution mass spectrometry (IDMS) with [13C]EE2 as internal standard. The technique was used to determine the concentration profiles of EE2 in the serum of female subjects who had taken oral contraceptives with different progestin components. The method has proved to be very reliable with respect to trueness, specificity, precision and detection sensitivity and offers considerable advantages compared with the immunological methods of measurement used to date. Forty-seven female volunteers took two different oral contraceptives containing EE2 combined with different progestins in accordance with a cross-over design. After the administration of 30 microg EE2 combined with 75 microg gestodene (EE2/GSD) or 150 microg desogestrel (EE2/DES), blood samples were taken from the subjects on certain days and in certain previously specified cycles in the course of 12 h after medication. The biometric analysis of the results showed that the concentration profiles of EE2 were in their statistics, significantly equivalent after the administration of either of the two oral contraceptives. The sometimes contradictory results found in former studies after the administration of the different contraceptives were presumably due to the methodological shortcomings of the radioimmunological measurement technique. With the use of the highly accurate and specific technique of IDMS it can now be unequivocally established that the different progestins in the tested oral contraceptives have no influence on the bioavailability of EE2 (area under EE2 serum concentration curves, as usually defined in pharmacokinetics).

  3. Rapid determination of (237)Np and plutonium isotopes in urine by inductively-coupled plasma mass spectrometry and alpha spectrometry.

    Science.gov (United States)

    Maxwell, Sherrod L; Culligan, Brian K; Jones, Vernon D; Nichols, Sheldon T; Noyes, Gary W; Bernard, Maureen A

    2011-08-01

    A new rapid separation method was developed for the measurement of plutonium and neptunium in urine samples by inductively-coupled plasma mass spectrometry (ICP-MS) and/or alpha spectrometry with enhanced uranium removal. This method allows separation and preconcentration of plutonium and neptunium in urine samples using stacked extraction chromatography cartridges and vacuum box flow rates to facilitate rapid separations. There is an increasing need to develop faster analytical methods for emergency response samples. There is also enormous benefit to having rapid bioassay methods in the event that a nuclear worker has an uptake (puncture wound, etc.) to assess the magnitude of the uptake and guide efforts to mitigate dose (e.g., tissue excision and chelation therapy). This new method focuses only on the rapid separation of plutonium and neptunium with enhanced removal of uranium. For ICP-MS, purified solutions must have low salt content and low concentration of uranium due to spectral interference of (238)U(1)H(+) on m/z 239. Uranium removal using this method is enhanced by loading plutonium and neptunium initially onto TEVA resin, then moving plutonium to DGA resin where additional purification from uranium is performed with a decontamination factor of almost 1×10(5). If UTEVA resin is added to the separation scheme, a decontamination factor of ~3 × 10(6) can be achieved.

  4. RETROSPECTIVE METHOD VALIDATION AND UNCERTAINTY ESTIMATION FOR ACTINIDES DETERMINATION IN EXCRETA BY ALPHA SPECTROMETRY.

    Science.gov (United States)

    Hernández, C; Sierra, I

    2016-09-01

    Two essential technical requirements of ISO 17025 guide for accreditation of testing and calibration laboratories are the validation of methods and the estimation of all sources of uncertainty that may affect the analytical result. Bioelimination Laboratory from Radiation Dosimetry Service of CIEMAT (Spain) uses alpha spectrometry to quantify alpha emitters (Pu, Am, Th, U and Cm isotopes) in urine and faecal samples from workers exposed to internal radiation. Therefore and as a step previous to achieving the ISO 17025 accreditation, the laboratory has performed retrospective studies based on the obtained results in the past few years to validate the analytical method. Uncertainty estimation was done identifying and quantifying all the contributions, and finally the overall combined standard uncertainty was calculated. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Sensitivity of ICP-MS, PERALS and alpha spectrometry for the determination of actinides

    International Nuclear Information System (INIS)

    Ayranov, M.; Krahenbiihl, U.; Rollin, S.; Burger, M.

    2004-01-01

    The purpose of this study was to compare the sensitivity of the three most popular techniques for the determination of minor actinides at environmental levels: ICP-MS, PERALS and solid state alpha spectrometry. For each method the limit of detection and the resolution were estimated in order to study the content and isotopic composition of the actinides. The sensitivities of the three determination techniques were compared. Two international reference materials, IAEA-135 (Irish Sea sediment) and IAEA-300 (Baltic Sea sediment) were analyzed for activity concentrations of 238 Pu, 239 Pu, 240 Pu, 241 Pu and 241 Am. (authors)

  6. The determination of radium-226 in uranium ores and mill products by alpha energy spectrometry

    International Nuclear Information System (INIS)

    Zimmerman, J.B.; Armstrong, V.C.

    1975-12-01

    A reliable routine procedure for determining 226 Ra by alpha energy spectrometry is described. Radium is isolated as sulphate from the sample matrix by co-precipitation with a small mass of barium and analysed using a ruggedized silicon surface barrier detector. The method is capable of providing high accuracy over a large 226 Ra concentration range and is applicable to materials such as uranium ores, uranium mill products and effluent streams. Samples resulting from nitric acid leach experiments with Elliot Lake ores were examined using the procedure. The distribution of 223 Ra, 224 Ra and 226 Ra between the leach products, (residue and leach liquor), is discussed. (author)

  7. Radioimmunoassay and liquid-chromatographic analysis for free cortisol in urine compared with isotope dilution-mass spectrometry

    International Nuclear Information System (INIS)

    Lantto, O.

    1982-01-01

    Three different routine methods for analysis for urinary cortisol with those by a highly specific reference method based on isotope dilution-mass spectrometry (I) were compared. A ''high-performance'' liquid-chromatographic method (II) gave the most comparable results (regression coefficient 0.86, intercept 9 nmol/L). For some urines much lower values were obtained by I than by II. Two radioimmunoassay (III) methods, one involving direct assay and one involving extraction, gave less-accurate results (regression coefficients of 1.87 and 1.52 and intercepts of 86 and 12 nmol/L, respectively), although values obtained by III and by I correlated well (r = 0.95-0.99), indicating a relation between the free cortisol and the compounds interfering in III. The apparent accuracy for the extraction method was improved by using as calibration standards urine samples previously assayed by I (regression coefficient 0.90, intercept 6 nmol/L). All four methods investigated showed a statistically significant sex-related difference in 24-h urinary cortisol excretion; evidently such a finding should be a prerequisite in any such method proposed for routine use

  8. On-line double isotope dilution laser ablation inductively coupled plasma mass spectrometry for the quantitative analysis of solid materials.

    Science.gov (United States)

    Fernández, Beatriz; Rodríguez-González, Pablo; García Alonso, J Ignacio; Malherbe, Julien; García-Fonseca, Sergio; Pereiro, Rosario; Sanz-Medel, Alfredo

    2014-12-03

    We report on the determination of trace elements in solid samples by the combination of on-line double isotope dilution and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The proposed method requires the sequential analysis of the sample and a certified natural abundance standard by on-line IDMS using the same isotopically-enriched spike solution. In this way, the mass fraction of the analyte in the sample can be directly referred to the certified standard so the previous characterization of the spike solution is not required. To validate the procedure, Sr, Rb and Pb were determined in certified reference materials with different matrices, including silicate glasses (SRM 610, 612 and 614) and powdered samples (PACS-2, SRM 2710a, SRM 1944, SRM 2702 and SRM 2780). The analysis of powdered samples was carried out both by the preparation of pressed pellets and by lithium borate fusion. Experimental results for the analysis of powdered samples were in agreement with the certified values for all materials. Relative standard deviations in the range of 6-21% for pressed pellets and 3-21% for fused solids were obtained from n=3 independent measurements. Minimal sample preparation, data treatment and consumption of the isotopically-enriched isotopes are the main advantages of the method over previously reported approaches. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Simulation study for high resolution alpha particle spectrometry with mesh type collimator

    International Nuclear Information System (INIS)

    Park, Seunghoon; Kwak, Sungwoo; Kang, Hanbyeol; Shin, Jungki; Park, Iljin

    2014-01-01

    An alpha particle spectrometry with a mesh type collimator plays a crucial role in identifying specific radionuclide in a radioactive source collected from the atmosphere or environment. The energy resolution is degraded without collimation because particles with a high angle have a longer path to travel in the air. Therefore, collision with the background increases. The collimator can cut out particles which traveling at a high angle. As a result, an energy distribution with high resolution can be obtained. Therefore, the mesh type collimator is simulated for high resolution alpha particle spectrometry. In conclusion, the collimator can improve resolution. With collimator, the collimator is a role of cutting out particles with a high angle, so, low energy tail and broadened energy distribution can be reduced. The mesh diameter is found out as an important factor to control resolution and counting efficiency. Therefore, a target particle, for example, 235 U, can be distinguished by a detector with a collimator under a mixture of various nuclides, for example: 232 U, 238 U, and 232 Th

  10. Rapid and Precise Measurement of Serum Branched-Chain and Aromatic Amino Acids by Isotope Dilution Liquid Chromatography Tandem Mass Spectrometry

    OpenAIRE

    Yang, Ruiyue; Dong, Jun; Guo, Hanbang; Li, Hongxia; Wang, Shu; Zhao, Haijian; Zhou, Weiyan; Yu, Songlin; Wang, Mo; Chen, Wenxiang

    2013-01-01

    BACKGROUND: Serum branched-chain and aromatic amino acids (BCAAs and AAAs) have emerged as predictors for the future development of diabetes and may aid in diabetes risk assessment. However, the current methods for the analysis of such amino acids in biological samples are time consuming. METHODS: An isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) method for serum BCAAs and AAAs was developed. The serum was mixed with isotope-labeled BCAA and AAA internal standar...

  11. Rapid determination of radium-224/226 in seawater sample by alpha spectrometry.

    Science.gov (United States)

    Song, Lijuan; Yang, Yonggang; Luo, Maoyi; Ma, Yan; Dai, Xiongxin

    2017-05-01

    A new radiochemical separation method has been developed for rapid determination of alpha-emitting radium isotopes in seawater samples. This method can be applied for the measurement of 226 Ra in seawater samples when 224 Ra is used as tracer for chemical recovery correction. Likewise, 226 Ra can also be added as tracer for the determination of 224 Ra in seawater sample. In the method, radium is first pre-concentrated with hydrous titanium oxide (HTiO) and is purified by combined anion/cation exchange column chromatographic separation. The radium in the eluate is then co-precipitated with HTiO, dissolved in 9 M H 2 SO 4 , and followed through a BaSO 4 micro-precipitation step to prepare a thin-layer counting source to determine the activities of 224 Ra/ 226 Ra by alpha spectrometry. Replicate spike and blank samples were measured to evaluate the performance of the procedure. The minimum detectable activity concentration was determined to be 0.5 mBq·L -1 for 226 Ra and 0.4 mBq·L -1 for 224 Ra in 1 L of seawater sample with a counting time of 48 h. The method is a promising candidate for rapid measurement for alpha-emitting Ra isotopes in a large population of environment water samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Use of 'dilute-and-shoot' liquid chromatography-high resolution mass spectrometry in preclinical research: application to a DMPK study of perhexiline in mouse plasma.

    Science.gov (United States)

    Esposito, Simone; Bracacel, Elena; Nibbio, Martina; Speziale, Roberto; Orsatti, Laura; Veneziano, Maria; Monteagudo, Edith; Bonelli, Fabio

    2016-01-25

    This work describes a simple, sensitive and rapid liquid chromatography-high resolution mass spectrometry method for the quantitation of perhexiline and the simultaneous detection of perhexiline metabolites in C57bl/6 mice plasma. Only 5 μL of plasma was used for analysis. Pretreatment was limited to a 100-fold dilution ('dilute-and-shoot'). The analyte was detected by high resolution mass spectrometry (Orbitrap™ technology). Three scan events were performed over the entire chromatogram. Targeted single ion monitoring with data dependent acquisition was employed for perhexiline quantitation and confirmation, while full scan was used to perform untargeted detection of perhexiline phase I and phase II circulating metabolites. The calibration curve was linear (r(2)=0.990) ranging from 0.305 ng/mL (LLOQ) to 10000 ng/mL. Matrix effect was limited to 6.1%. The method was applied to a pharmacokinetic study of perhexiline in mouse plasma and the results obtained were compared to a standard sample preparation method based on protein precipitation and liquid chromatography-tandem mass spectrometry (MRM mode) detection. The new approach provided comparable results in terms of pharmacokinetics parameters estimate with a high sensitivity, additional information on perhexiline circulating metabolites and a low consumption of biological sample. The combination of the 'dilute-and-shoot' approach together with HRMS targeted and untargeted detection represents a suitable alternative to classic bioanalytical approaches in preclinical research. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Identification and quantification of human DNA repair protein NEIL1 by liquid chromatography/isotope-dilution tandem mass spectrometry.

    Science.gov (United States)

    Reddy, Prasad T; Jaruga, Pawel; Kirkali, Güldal; Tuna, Gamze; Nelson, Bryant C; Dizdaroglu, Miral

    2013-02-01

    Accumulated evidence points to DNA repair capacity as an important factor in cancer and other diseases. DNA repair proteins are promising drug targets and are emerging as prognostic and therapeutic biomarkers. Thus, the knowledge of the overexpression or underexpression levels of DNA repair proteins in tissues will be of fundamental importance. In this work, mass spectrometric assays were developed for the measurement in tissues of the human DNA repair protein NEIL1 (hNEIL1), which is involved in base excision and nucleotide excision repair pathways of oxidatively induced DNA damage. Liquid chromatography/isotope-dilution tandem mass spectrometry (LC-MS/MS), in combination with a purified and fully characterized recombinant (15)N-labeled analogue of hNEIL1 ((15)N-hNEIL1) as an internal standard, was utilized to develop an accurate method for the quantification of hNEIL1. Both hNEIL1 and (15)N-hNEIL1 were hydrolyzed with trypsin, and 18 tryptic peptides from each protein were identified by LC-MS/MS on the basis of their full-scan mass spectra. These peptides matched the theoretical peptides expected from trypsin hydrolysis of hNEIL1 and provided a statistically significant protein score that would unequivocally identify hNEIL1. The product ion spectra of the tryptic peptides from both proteins were recorded, and the characteristic product ions were defined. Selected-reaction monitoring was used to analyze mixtures of hNEIL1 and (15)N-hNEIL1 on the basis of product ions. Additional confirmation of positive identification was demonstrated via separation of the proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and in-gel tryptic digestion followed by LC-MS/MS analysis. These results suggest that the developed assays would be highly suitable for the in vivo positive identification and accurate quantification of hNEIL1 in tissues.

  14. Isotope Dilution Mass Spectrometry for Highly Precise Determination of Dissolved Inorganic Carbon in Seawater Aiming at Climate Change Studies.

    Science.gov (United States)

    Freije-Carrelo, Laura; Alonso Sobrado, Laura; Moldovan, Mariella; Encinar, Jorge Ruiz; García Alonso, J Ignacio

    2018-04-03

    Dissolved inorganic carbon (DIC) is one of the most important parameters to be measured in seawaters for climate change studies. Its quantitative assessment requires analytical methodologies with overall uncertainties around 0.05% RSD for clear evaluation of temporal trends. Herein, two alternative isotope dilution mass spectrometry (IDMS) methodologies (online and species-specific) using an isotope ratio mass spectrometer (IRMS) and two calculation procedures for each methodology have been compared. As a result, a new method for the determination of DIC in seawaters, based on species-specific IDMS with isotope pattern deconvolution calculation, was developed and validated. A 13 C-enriched bicarbonate tracer was added to the sample and, after equilibration and acidification, the isotope abundances at CO 2 masses 44, 45, and 46 were measured on an IRMS instrument. Notably, early spiking allows correcting for evaporations and/or adsorptions during sample preparation and storage and could be carried out immediately after sampling. Full uncertainty budgets were calculated taking into account all the factors involved in the determination (initial weights, concentration and isotope abundances of standards, and final IRMS measurements). The average DIC value obtained for CRM seawater agreed very well with the certified value. Propagated precision obtained ranged from 0.035 to 0.050% RSD for individual sample triplicates. Reproducibility, assessed by three independent experiments carried out in different working days, was excellent as well (-0.01% and 0.057%, error and full combined uncertainty, respectively). Additionally, the approach proposed improves on established methods by simplicity, higher throughput (15 min per sample), and lower volume requirements (10 mL).

  15. Simultaneous analysis of urinary phthalate metabolites of residents in Korea using isotope dilution gas chromatography-mass spectrometry.

    Science.gov (United States)

    Kim, Miok; Song, Na Rae; Choi, Jong-Ho; Lee, Jeongae; Pyo, Heesoo

    2014-02-01

    Phthalates are used in industry products, household items, and medical tools as plasticizers. Human exposure to phthalates has raised concern about its toxicity. In the present study, optimization was conducted for the simultaneous analysis of eight kinds of phthalate metabolites using gas chromatography-mass spectrometry (GC-MS): MEP, MiBP, MnBP, MBzP, MiNP, MEHP, MEOHP, and MEHHP. In order to minimize the matrix effect and to do quantitative analysis, isotope dilution and LLE-GC-MS methods were performed. Urine samples were enzymatically hydrolyzed, extracted with a mixture of n-hexane and ethyl ether (8:2; v:v), and subsequently derivatized with trimethylsilylation. All eight kinds of analytes showed clear resolution and high reproducibility in GC-MS results. The method detection limit ranged from 0.05 ng/mL to 0.2 ng/mL. Calibration curves were found to be linear from 0.2 to 100 ng/mL with -(2)>0.992. The relative standard deviation of the intraday precision using water and urine ranged from 2.1% to 16.3%. The analysis was performed with urine samples that were collected from adults residing in the Republic of Korea. The analyzed concentration results were compared according to gender and region. As a result, DEHP metabolites showed the highest detected concentration (75.92 μg/g creatinine, 100%), and MiNP, a metabolite of DiNP, showed the lowest detected concentration (0.42 μg/g creatinine, 22.5%). On average, female urine (200.76 μg/g creatinine) had a higher detected concentration of ∑8 phthalate metabolites than male urine. Samples from rural regions (211.96 μg/g creatinine) had higher levels than samples from urban regions. © 2013.

  16. [International comparison APMP. QM-S6: determination of clenbuterol in porcine meat by isotopic dilution mass spectrometry].

    Science.gov (United States)

    Xu, Sen; Li, Xiuqin; Luo, Ximing; Zhang, Qinghe

    2014-10-01

    A method was developed for the determination of clenbuterol in porcine meat by iso- topic dilution mass spectrometry (IDMS). National Institute of Metrology of China (NIM) par- ticipated in the international comparison activity organized by Asia Pacific Metrology (APMP) and got an international mutual recognition result using this method. The important factors of the method, such as the spray voltage, mobile phase, chromatographic column, extraction, purification and filtration conditions were investigated to acquire optimum conditions. The opti- mization results showed that the composition and pH value of the mobile phase had effects on the response of the mass spectrum of clenbuterol and the optimal value of the spray voltage. The solvent of sample had influences on the chromatographic retention behavior of clenbuterol. It was found that methanol caused a serious solvent effect, even made chromatographic peak split. Since clenbuterol was easily adsorbed on hydrophilic filter membranes and solid phase extraction columns, there were interference suppressions for the quantification of clenbuterol because of the eluate of the solid phase extraction columns. The homogenate method with extraction solvent of 0.1% (v/v) formic acid in acetonitrile had the highest extraction efficiency. The limit of the detection (LOD, S/N > 3) of the method was 0.2 μg/kg. The determination results of clenbuterol in the porcine meat by this method were 5.18 μg/kg ± 0.50 μg/kg (k = 2). This method is accurate, reliable, reproducible, and suitable for the determination of clenbuterol with trace quantity in porcine meat.

  17. Dilute-and-shoot coupled to nanoflow liquid chromatography high resolution mass spectrometry for the determination of drugs of abuse and sport drugs in human urine.

    Science.gov (United States)

    Alcántara-Durán, Jaime; Moreno-González, David; Beneito-Cambra, Miriam; García-Reyes, Juan F

    2018-05-15

    In this work, a sensitive nanoflow liquid chromatography high-resolution mass spectrometry screening method has been developed for the determination of multiclass drugs of abuse and sport drugs in human urine. 81 drugs belonging to different multiclass pharmaceuticals were targeted. The method is based on the use of a nanoLC column (75 µm × 150 mm, 3 µm particle size and 100 Å pore) with the nanospray emitter tip integrated so that dead volumes are significantly minimized. Data acquisition method included both full-scan and all ion fragmentation experiments using an Orbitrap analyser (Q-Exactive) operated in the positive ionization mode. To increase laboratory throughput, a dilute-and-shoot methodology has been tested and proposed, based solely on direct urine dilution without further sample workup. Matrix effects were evaluated, showing a negligible effect for all studied compounds when a dilution 1:50 was implemented. Despite this high-dilution factor, limits of quantification were still satisfactory, with values below 5 µg L -1 in most cases, being lower than their minimum required performance limits correspond established by the World Anti-Doping Agency. Therefore, the use of the dilute-and-shoot method with the enhanced sensitivity provided by nanoflow LC setup could be useful tool for the determination of studied compounds in drug testing, thus increasing laboratory performance, because a minimum sample treatment steps are required. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Uranium isotopes determination in urine samples using alpha spectrometry and ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, Mychelle M.L.; Maihara, Vera A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Tine, Fernanda D.; Santos, Sandra M.C.; Bonifacio, Rodrigo L.; Taddei, Maria HelenaT. [Comissao Nacional de Energia Nuclear (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil). Laboratorio de Pocos de Caldas

    2015-07-01

    The action of determining the concentration of uranium isotopes in biological samples, 'in vitro' bioassay, is an indirect method for evaluating the incorporation and quantification of these radionuclides internally deposited. When incorporated, these radionuclides tend to be disposed through excretion, with urine being the main source of data because it can be easily collected and analyzed. The most widely used methods for determination of uranium isotopes ({sup 234}U, {sup 235}U and {sup 238}U) are Alpha Spectrometry and ICP-MS. This work presents a comparative study for the determination of uranium isotopes using these two methodologies in real samples from occupationally exposed workers. In order to validate the methodology, a sample of the intercomparison exercise organized by PROCORAD (Association pour la Promotion du Controle de Qualite des Analyses de Biologie Medicale em Radiotoxicologie) was used, and the results were statistically compared applying the Student's t-test. (author)

  19. Standard test method for the radiochemical determination of americium-241 in soil by alpha spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This method covers the determination of americium–241 in soil by means of chemical separations and alpha spectrometry. It is designed to analyze up to ten grams of soil or other sample matrices that contain up to 30 mg of combined rare earths. This method allows the determination of americium–241 concentrations from ambient levels to applicable standards. The values stated in SI units are to be regarded as standard. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precaution statements, see Section 10.

  20. An improved method for determination of uranium isotopic composition in urine by alpha spectrometry

    International Nuclear Information System (INIS)

    Duarte, C.L.; Szeles, M.S.M.F.

    1994-01-01

    A comparative study of source preparation techniques to determine uranium isotopic composition by alpha spectrometry, namely electrodeposition and chemical stripping with polymeric membrane containing trioctylphosphine oxide (TOPO), is presented. The mean yield obtained for electrodeposition and TOPO deposition were 85% and 74%, respectively. The mean activity ratio 235 U/ 238 U were 0.044 and 0.042 and the ratio 234 U/ 238 U were 0.994 and 1.009, using electrodeposition and TOPO deposition techniques, respectively. The method of uranium separation from urine using an ion-exchange resin Dowex 1 x 8, chloride form and citrate form, was also studied. The obtained global yields of these methods were 50% and 41%, respectively. (author)

  1. Characterizing uranium oxide reference particles for isotopic abundances and uranium mass by single particle isotope dilution mass spectrometry

    International Nuclear Information System (INIS)

    Kraiem, M.; Richter, S.; Erdmann, N.; Kühn, H.; Hedberg, M.; Aregbe, Y.

    2012-01-01

    Highlights: ► A method to quantify the U mass in single micron particles by ID-TIMS was developed. ► Well-characterized monodisperse U-oxide particles produced by an aerosol generator were used. ► A linear correlation between the mass of U and the volume of particle(s) was found. ► The method developed is suitable for determining the amount of U in a particulate reference material. - Abstract: Uranium and plutonium particulate test materials are becoming increasingly important as the reliability of measurement results has to be demonstrated to regulatory bodies responsible for maintaining effective nuclear safeguards. In order to address this issue, the Institute for Reference Materials and Measurements (IRMM) in collaboration with the Institute for Transuranium Elements (ITU) has initiated a study to investigate the feasibility of preparing and characterizing a uranium particle reference material for nuclear safeguards, which is finally certified for isotopic abundances and for the uranium mass per particle. Such control particles are specifically required to evaluate responses of instruments based on mass spectrometric detection (e.g. SIMS, TIMS, LA-ICPMS) and to help ensuring the reliability and comparability of measurement results worldwide. In this paper, a methodology is described which allows quantifying the uranium mass in single micron particles by isotope dilution thermal ionization mass spectrometry (ID-TIMS). This methodology is characterized by substantial improvements recently achieved at IRMM in terms of sensitivity and measurement accuracy in the field of uranium particle analysis by TIMS. The use of monodisperse uranium oxide particles prepared using an aerosol generation technique developed at ITU, which is capable of producing particles of well-characterized size and isotopic composition was exploited. The evidence of a straightforward correlation between the particle volume and the mass of uranium was demonstrated in this study

  2. Simultaneous determination of creatinine and creatine in human serum by double-spike isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS).

    Science.gov (United States)

    Fernández-Fernández, Mario; Rodríguez-González, Pablo; Añón Álvarez, M Elena; Rodríguez, Felix; Menéndez, Francisco V Álvarez; García Alonso, J Ignacio

    2015-04-07

    This work describes the first multiple spiking isotope dilution procedure for organic compounds using (13)C labeling. A double-spiking isotope dilution method capable of correcting and quantifying the creatine-creatinine interconversion occurring during the analytical determination of both compounds in human serum is presented. The determination of serum creatinine may be affected by the interconversion between creatine and creatinine during sample preparation or by inefficient chemical separation of those compounds by solid phase extraction (SPE). The methodology is based on the use differently labeled (13)C analogues ((13)C1-creatinine and (13)C2-creatine), the measurement of the isotopic distribution of creatine and creatinine by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and the application of multiple linear regression. Five different lyophilized serum-based controls and two certified human serum reference materials (ERM-DA252a and ERM-DA253a) were analyzed to evaluate the accuracy and precision of the proposed double-spike LC-MS/MS method. The methodology was applied to study the creatine-creatinine interconversion during LC-MS/MS and gas chromatography-mass spectrometry (GC-MS) analyses and the separation efficiency of the SPE step required in the traditional gas chromatography-isotope dilution mass spectrometry (GC-IDMS) reference methods employed for the determination of serum creatinine. The analysis of real serum samples by GC-MS showed that creatine-creatinine separation by SPE can be a nonquantitative step that may induce creatinine overestimations up to 28% in samples containing high amounts of creatine. Also, a detectable conversion of creatine into creatinine was observed during sample preparation for LC-MS/MS. The developed double-spike LC-MS/MS improves the current state of the art for the determination of creatinine in human serum by isotope dilution mass spectrometry (IDMS), because corrections are made for all the possible errors

  3. Electrospray mass spectrometry characterization of post-translational modifications of barley alpha-amylase 1 produced in yeast

    DEFF Research Database (Denmark)

    Søgaard, M; Andersen, Jens S.; Roepstorff, P

    1993-01-01

    We have used electrospray mass spectrometry (ESMS) in combination with protein chemistry and genetics to delineate post-translational modifications in yeast of barley alpha-amylase 1 (AMY1), a 45 kD enzyme crucial for production of malt, an important starting material in the manufacture of beer...

  4. Automated gravimetric sample pretreatment using an industrial robot for the high-precision determination of plutonium by isotope dilution mass spectrometry.

    Science.gov (United States)

    Surugaya, Naoki; Hiyama, Toshiaki; Watahiki, Masaru

    2008-06-01

    A robotized sample-preparation method for the determination of Pu, which is recovered by extraction reprocessing of spent nuclear fuel, by isotope dilution mass spectrometry (IDMS) is described. The automated system uses a six-axis industrial robot, whose motility is very fast, accurate, and flexible, installed in a glove box. The automation of the weighing and dilution steps enables operator-unattended sample pretreatment for the high-precision analysis of Pu in aqueous solutions. Using the developed system, the Pu concentration in a HNO(3) medium was successfully determined using a set of subsequent mass spectrometric measurements. The relative uncertainty in determining the Pu concentration by IDMS using this system was estimated to be less than 0.1% (k = 2), which is equal to that expected of a talented analyst. The operation time required was the same as that for a skilled operator.

  5. Automated gravimetric sample pretreatment using an industrial robot for the high-precision determination of plutonium by isotope dilution mass spectrometry

    International Nuclear Information System (INIS)

    Surugaya, Naoki; Hiyama, Toshiaki; Watahiki, Masaru

    2008-01-01

    A robotized sample-preparation method for the determination of Pu, which is recovered by extraction reprocessing of spent nuclear fuel, by isotope dilution mass spectrometry (IDMS) is described. The automated system uses a six-axis industrial robot, whose motility is very fast, accurate, and flexible, installed in a glove box. The automation of the weighing and dilution steps enables operator-unattended sample pretreatment for the high-precision analysis of Pu in aqueous solutions. Using the developed system, the Pu concentration in a HNO 3 medium was successfully determined using a set of subsequent mass spectrometric measurements. The relative uncertainty in determining the Pu concentration by IDMS using this system was estimated to be less than 0.1% (k=2), which is equal to that expected of a talented analysis. The operation time required was the same as that for a skilled operator. (author)

  6. Determination of uranium and thorium isotopes by solid phase extraction and alpha spectrometry

    International Nuclear Information System (INIS)

    Kuruc, J.; Kovacova, M.; Strisovska, J.; Galanda, D.

    2013-01-01

    The aim of this work was to test the modified method suitable for the separation of isotopes of uranium and thorium samples of rocks, including gold ore and gold concentrate using of extraction chromatography method, after digestion of the sample, concentrating, separate the isotopes of uranium and thorium isotopes to prepare sources for the measurement of alpha spectra. Samples of rocks, gold ore and gold concentrate were digered in microwave decomposition in the environment of hydrogen peroxide and concentrated nitric acid. For the separation of uranium and thorium the vacuum box with cartridges DGA Resin and Resin(R) UTEVA (Triskem International, France) was used. Both sorbents allow separation of uranium from thorium. The results confirmed that the both sorbents give the same results within expanded uncertainty. The mass activity of monitored uranium and thorium radioisotopes was determined by alpha spectrometry method. The yields of separation were determined using uranium-232 as a tracer radionuclide; the activity of 232 U was 0.1438 Bq. Alpha spectra were measured on the Alpha spectrometer EG and G ORTEC 576A with the software MAESTRO, MCA Emulator and Gamma Vision-32 for Windows, USA. Mass activities of radionuclides were converted to mass concentration of isotopes 238 U, 234 U, 232 Th, 230 Th and 228 Th. The highest concentration of 238 U was sampled in granodiorite (Tunnel S-XIV-2, southwards, mining of Cu ore, not working there since 1990), where m( 238 U) = (0.81 ± 0.09) mg kg -1 (DGA Resin) and m( 238 U) = (0.90 ± 0.09) mg kg -1 (UTEVA(R) Resin), as well as m( 232 Th) = (18.8 ± 1.7) mg kg -1 (DGA Resin) and m( 232 Th) = (17.8 ± 1.5) mg kg -1 (UTEVA(R) Resin). In other samples of rocks, gold ore and gold concentrates have specific masses of isotopes of uranium and thorium two-to ten-folds lower. It can be concluded that the rocks, gold ores and concentrates of gold from the 'Rozalia' mine contain lower concentrations of uranium several times against

  7. Optimization of parameters of alpha spectrometry with silicon detector for low level measurements of actinides in environmental samples.

    Science.gov (United States)

    Rao, D D; Sudheendran, V; Sarkar, P K

    2012-08-01

    Determination of actinides in environmental and biological samples is an important activity of radiation protection program at nuclear energy facilities. High resolution alpha spectrometry with passivated ion implanted Silicon detectors is widely used for the determination of actinides concentration. Low levels of activity concentrations in these samples often require long counting duration of a few days to obtain accurate and statistically significant data for further impact assessment. In alpha spectrometry, the chamber in which Si detector operated is a critical component and maintained at a desired vacuum for minimizing the alpha particle attenuation. Experimental evaluation of variations in energy resolution and tailing of alpha spectra was investigated under different chamber air pressures from about 6.7 Pa to more than 2700 Pa under the chamber hold mode and pump electrically switched off conditions. As part of validation, data collected on an IAEA inter-comparison exercise sample are presented under short and long counting durations with pump operating and switched off conditions respectively. It has been observed that the FWHM values do not significantly degrade, to impact the low and medium level concentration alpha spectra, for variations in vacuum chamber pressures from about 6.7 Pa to 2700 Pa. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. A sequential extraction procedure to determine Ra and U isotopes by alpha-particle spectrometry in selective leachates

    International Nuclear Information System (INIS)

    Aguado, J.L.; Bolivar, J.P.; San-Miguel, E.G.; Garcia-Tenorio, R.

    2003-01-01

    A radiochemical sequential extraction procedure has been developed in our laboratory to determine 226 Ra and 234,238 U by alpha spectrometry in environmental samples. This method has been validated for both radionuclides by comparing in selected samples the values obtained through its application with the results obtained by applying alternative procedures. Recoveries obtained, counting periods applied and background levels found in the alpha spectra give suitable detection limits to allow the Ra and U determination in operational forms defined in riverbed contaminated sediments. Results obtained in these speciation studies show that 226 Ra and 234,238 U contamination tend to be associated to precipitated forms of the sediments. (author)

  9. Determination of uranium and polonium in Spa rus aura ta by alpha spectrometry

    International Nuclear Information System (INIS)

    Luna P, M.; Renteria, M.; Montero C, M. E.; Manjon C, G.; Diaz, I.

    2012-01-01

    The aim of this study was optimizing conditions for the specific activities determination of some uranium-series radionuclides present in Spa rus aura ta by alpha spectrometry. Determinations of specific activities were conducted varying the type of digestion: acid attack on hot plate, controlled microwave digestion and acid attack after calcination of the sample. The latter procedure was applied only to the case of uranium isotopes determination. The variation in the isotope extraction method consisted of applying the techniques of liquid-liquid extracting using Tributyl phosphate or chromatographic UTEVA resin. Results depending on the type of treatment given to the samples were compared based on obtained chemical yields. The results reveal a higher bioaccumulation of polonium in the liver sample, with activities of 0.809, 2.495 and 2.439 Bq kg -1 fresh wt compared with the fillet. The best chemical yields of polonium were close to 60% for samples that were digested by microwave. In the case of uranium the best chemical yields, close to 80% for fillet, were obtained with a previous calcination of the sample and using the UTEVA resin. (Author)

  10. Aerosols in King George Island (Antarctic peninsula) using PIXE and alpha spectrometry

    International Nuclear Information System (INIS)

    Dias da Cunha, K.; Medeiros, G.; Leal, M.A.; Lima, C.; Dalia, K.C.

    2009-01-01

    The aim of this study was to characterize the airborne particles and particles deposited in the recent snow samples collected at King George Island (Admiralty Bay) in order to evaluate the possible local sources of airborne particles and the aerosol transport from South America to Antarctic at sea level. Airborne particles samples were collected using a cascade impactor and cyclones at several sampling points at Admiralty Bay. Airborne particles were also collected during the ship travel from Rio de Janeiro to Antarctica. The recent snow samples and aerosols collected at several sampling points at Admiralty Bay were analyzed by PIXE for the determination of the elemental mass concentration. Snow samples were analyzed by alpha spectrometry to determine the 232Th, 228Th, 238U and 234U concentrations in snow. The Mass Median Aerodynamic Diameter of airborne particles was determined. The results suggest that there is a correlation between the aerosol samples and the particles deposited in the snow, but the elemental mass distributions are not equal. The snow elemental concentration can be used as an indicator of the elements present in the aerosols. The local aerosol sources (natural and anthropogenic) have been considered to characterize the aerosol transport to Antarctic, mainly King George Island. The main aerosol sources are the marine spray, weathering of local rocks and anthropogenic sources, as the diesel burning in the island. Besides the local aerosol sources the transport of airborne particles from south Atlantic to Antarctic is an important source of airborne particles at King George Island. (author)

  11. Determination of uranium and polonium in Spa rus aura ta by alpha spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Luna P, M.; Renteria, M.; Montero C, M. E. [Centro de Investigacion en Materiales Avanzados, S. C., Miguel de Cervantes No. 120, Complejo Industrial Chihuahua, 31109 Chihuahua (Mexico); Manjon C, G.; Diaz, I., E-mail: elena.montero@cimav.edu.mx [Universidad de Sevilla, Escuela Tecnica Superior de Arquitectura, Departamento de Fisica Aplicada II, San Fernando No. 4, 41004 Sevilla (Spain)

    2012-06-15

    The aim of this study was optimizing conditions for the specific activities determination of some uranium-series radionuclides present in Spa rus aura ta by alpha spectrometry. Determinations of specific activities were conducted varying the type of digestion: acid attack on hot plate, controlled microwave digestion and acid attack after calcination of the sample. The latter procedure was applied only to the case of uranium isotopes determination. The variation in the isotope extraction method consisted of applying the techniques of liquid-liquid extracting using Tributyl phosphate or chromatographic UTEVA resin. Results depending on the type of treatment given to the samples were compared based on obtained chemical yields. The results reveal a higher bioaccumulation of polonium in the liver sample, with activities of 0.809, 2.495 and 2.439 Bq kg{sup -1} fresh wt compared with the fillet. The best chemical yields of polonium were close to 60% for samples that were digested by microwave. In the case of uranium the best chemical yields, close to 80% for fillet, were obtained with a previous calcination of the sample and using the UTEVA resin. (Author)

  12. Development of an on-line isotope dilution laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method for determination of boron in silicon wafers.

    Science.gov (United States)

    Yang, Chao-Kai; Chi, Po-Hsiang; Lin, Yong-Chine; Sun, Yuh-Chang; Yang, Mo-Hsiung

    2010-01-15

    A method has been developed based on an on-line isotope dilution technique couple with laser ablation/inductively coupled plasma mass spectrometry (LA-ICP-MS), for the determination of boron in p-type silicon wafers. The laser-ablated sample aerosol was mixed on-line with an enriched boron aerosol supplied continuously using a conventional nebulization system. Upon mixing the two aerosol streams, the isotope ratio of boron changed rapidly and was then recorded by the ICP-MS system for subsequent quantification based on the isotope dilution principle. As an on-line solid analysis method, this system accurately quantifies boron concentrations in silicon wafers without the need for an internal or external solid reference standard material. Using this on-line isotope dilution technique, the limit of detection for boron in silicon wafers is 2.8x10(15)atomscm(-3). The analytical results obtained using this on-line methodology agree well with those obtained using wet chemical digestion methods for the analysis of p-type silicon wafers containing boron concentrations ranging from 1.0x10(16) to 9.6x10(18)atomscm(-3).

  13. Interaction between alpha and upsilon-crystallin, common to the eye of the Australian platypus, by radical probe mass spectrometry.

    Science.gov (United States)

    Issa, Samah; Downard, Kevin M

    2006-10-01

    The interaction between alpha-crystallin and upsilon-crystallin, a class recently discovered in the eye of the Australian platypus, has been shown by native shift gel assay and examined by radical probe mass spectrometry in the context of the ability of alpha-crystallin to protect upsilon-crystallin from oxidation and oxidative damage through radical-based oxidative stress mechanisms. Residues 22-41, 132-148, 212-227 and 245-264 of upsilon-crystallin display the greatest protection when interacted with alpha-crystallin at a ratio of 2 : 1 observed for the complex, which is commensurate with their levels measured in the eye of the platypus. Across each domain, a delay in the onset of oxidative damage is observed as the time of exposure to radicals is increased. The results are discussed in the context of the structure of the porcine homologue of upsilon-crystallin. Copyright 2006 John Wiley & Sons, Ltd.

  14. Assessment of the amount of body water in the Red Knot (Calidris canutus): an evaluation of the principle of isotope dilution with 2H, (17)O, and (18)O as measured with laser spectrometry and isotope ratio mass spectrometry.

    Science.gov (United States)

    Kerstel, Erik R T; Piersma, Theunis; Piersma, Theunis A J; Gessaman, James A; Gessaman, G Jim; Dekinga, Anne; Meijer, Harro A J; Visser, G Henk

    2006-03-01

    We have used the isotope dilution technique to study changes in the body composition of a migratory shorebird species (Red Knot, Calidris canutus) through an assessment of the amount of body water in it. Birds were quantitatively injected with a dose of water with elevated concentrations of 2H, (17)O, and (18)O. Thereafter, blood samples were taken and distilled. The resulting water samples were analysed using an isotope ratio mass spectrometry (for 2H and (18)O only) and a stable isotope ratio infrared laser spectrometry (2H, (17)O, and (18)O) to yield estimates of the amount of body water in the birds, which in turn could be correlated to the amount of body fat. Here, we validate laser spectrometry against mass spectrometry and show that all three isotopes may be used for body water determinations. This opens the way to the extension of the doubly labelled water method, used for the determination of energy expenditure, to a triply labelled water method, incorporating an evaporative water loss correction on a subject-by-subject basis or, alternatively, the reduction of the analytical errors by statistically combining the (17)O and (18)O measurements.

  15. A novel quantification strategy of transferrin and albumin in human serum by species-unspecific isotope dilution laser ablation inductively coupled plasma mass spectrometry (ICP-MS)

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Liuxing, E-mail: fenglx@nim.ac.cn; Zhang, Dan; Wang, Jun; Shen, Dairui; Li, Hongmei

    2015-07-16

    Highlights: • Species-unspecific ID-PAGE-LA-ICP-MS was used to quantify Alb and Tf in human serum. • Addition methods of species-unspecific {sup 34}S spike were evaluated. • Isotope change conditions were investigated to reach satisfactory “isotope equilibration”. • Human serum CRM (ERM-DA470k/IFCC) was used to validate the new arrangements. • The developed method offers potential for accurate quantification of protein by ID-PAGE-LA-ICP-MS. - Abstract: Species-specific (SS) isotope dilution analysis with gel electrophoresis (GE)-laser ablation (LA)-ICP-MS is a promising technique for the quantification of particular metal-binding proteins in biological samples. However, unavailable isotopically enriched spike and metal losses in GE separation are main limitations for SS-isotope dilution PAGE-LA-ICP-MS. In this study, we report for the first time the absolute quantification of transferrin (Tf) and albumin (Alb) in human serum by non-denaturing (native) GE combined with species-unspecific isotope dilution mass spectrometry (IDMS). In order to achieve a homogeneous distribution of both protein and isotope-enriched spike (simulated isotope equilibration), immersing the protein strips with {sup 34}S spike solution after gel electrophoresis was demonstrated to be an effective way of spike addition. Furthermore, effects of immersion time and {sup 34}S spike concentration were investigated to obtain optimal conditions of the post-electrophoresis isotope dilution method. The relative mass of spike and ablated sample (m{sub sp}/m{sub sam}) in IDMS equation was calculated by standard Tf and Alb proteins, which could be applied to the quantification of Tf and Alb in ERM-DA470k/IFCC for method confirmation. The results were in agreement with the certified value with good precision and small uncertainty (1.5–3%). In this method, species-specific spike protein is not necessary and the integrity of the heteroatom-protein could be maintained in sample preparation

  16. Concentration of Radon Progeny in Air by Alpha Spectrometry Measurement; Medida de los descendientes del radon en aire por Espectrometria Alfa

    Energy Technology Data Exchange (ETDEWEB)

    Acena, M. L.; Crespo, M. T.

    1989-07-01

    The concentration of radon progeny in air has been determined by alpha spectrometry measurement of 214 Po and 318 Po. A known volume of air was passed through a filter, then the alpha activity was directly measured on this filter. (Author) 15 refs.

  17. Use of an internal standard 233U, 236U to improve the accuracy of isotopic uranium analysis by thermal ionization mass spectrometry. Application to isotope dilution analysis

    International Nuclear Information System (INIS)

    Chevalier, C.; Hagemann, R.; Lucas, M.; Devillers, C.

    1982-01-01

    A method using a calibrated mixture of isotopes 233 U and 236 U has been developed in order to correct the isotopic fractionation which limits the accuracy of isotopic analysis by thermal ionization mass spectrometry. The 236/233 internal standard ratio is calibrated against the 235/238 ratios of uranium isotopic standards. To perform the analysis of the unknown sample, the latter is mixed with the internal standard, the differences between the true value and the observed values of the 236/233 ratio allows the determination of a correction factor, which is applied to the measured 235/238 ratio values. Since 1978, 235 U abundance measurements on series of samples have been performed, using this technique; data are obtained with an accuracy better than 0,05%. It is intended to apply this method for precise determination of 238/233 ratio in the case of uranium concentration measurements by isotope dilution [fr

  18. Application of Isotope Dilution Mass Spectrometry for Reference Measurements of Cadmium. Copper, Mercury, Lead, Zinc and Methyl Mercury in Marine Sediment Sample

    Directory of Open Access Journals (Sweden)

    Vasileva E.

    2013-04-01

    Full Text Available Marine sediment was selected as a test sample for the laboratory inter-comparison studies organized by the Environment Laboratoryes of the International Atomic Energy. The analytical procedure to establish the reference values for the Cd, Cu, Hg, Methyl Hg, Pb and Zn amount contents was based on Isotope Dilution Inductively Coupled Plasma-Mass Spectrometry (ID ICP-MS applied as a primary method of measurement..The Hg and Methyl Hg determination will be detailed more specifically because of the problems encountered with this element, including sample homogeneity issues, memory effects and possible matrix effects during the ICP- MS measurement stage. Reference values, traceable to the SI, with total uncertainties of less than 2% relative expanded uncertainty (k=2 were obtained for Cd, Cu, Zn and Pb and around 5% for Hg and CH3Hg.

  19. Determination of Glyphosate, its Degradation Product Aminomethylphosphonic Acid, and Glufosinate, in Water by Isotope Dilution and Online Solid-Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry

    Science.gov (United States)

    Meyer, Michael T.; Loftin, Keith A.; Lee, Edward A.; Hinshaw, Gary H.; Dietze, Julie E.; Scribner, Elisabeth A.

    2009-01-01

    The U.S. Geological Survey method (0-2141-09) presented is approved for the determination of glyphosate, its degradation product aminomethylphosphonic acid (AMPA), and glufosinate in water. It was was validated to demonstrate the method detection levels (MDL), compare isotope dilution to standard addition, and evaluate method and compound stability. The original method USGS analytical method 0-2136-01 was developed using liquid chromatography/mass spectrometry and quantitation by standard addition. Lower method detection levels and increased specificity were achieved in the modified method, 0-2141-09, by using liquid chromatography/tandem mass spectrometry (LC/MS/MS). The use of isotope dilution for glyphosate and AMPA and pseudo isotope dilution of glufosinate in place of standard addition was evaluated. Stable-isotope labeled AMPA and glyphosate were used as the isotope dilution standards. In addition, the stability of glyphosate and AMPA was studied in raw filtered and derivatized water samples. The stable-isotope labeled glyphosate and AMPA standards were added to each water sample and the samples then derivatized with 9-fluorenylmethylchloroformate. After derivatization, samples were concentrated using automated online solid-phase extraction (SPE) followed by elution in-line with the LC mobile phase; the compounds separated and then were analyzed by LC/MS/MS using electrospray ionization in negative-ion mode with multiple-reaction monitoring. The deprotonated derivatized parent molecule and two daughter-ion transition pairs were identified and optimized for glyphosate, AMPA, glufosinate, and the glyphosate and AMPA stable-isotope labeled internal standards. Quantitative comparison between standard addition and isotope dilution was conducted using 473 samples analyzed between April 2004 and June 2006. The mean percent difference and relative standard deviation between the two quantitation methods was 7.6 plus or minus 6.30 (n = 179), AMPA 9.6 plus or minus 8

  20. Pre-column dilution large volume injection ultra-high performance liquid chromatography-tandem mass spectrometry for the analysis of multi-class pesticides in cabbages.

    Science.gov (United States)

    Zhong, Qisheng; Shen, Lingling; Liu, Jiaqi; Yu, Dianbao; Li, Siming; Yao, Jinting; Zhan, Song; Huang, Taohong; Hashi, Yuki; Kawano, Shin-ichi; Liu, Zhaofeng; Zhou, Ting

    2016-04-15

    Pre-column dilution large volume injection (PD-LVI), a novel sample injection technique for reverse phase ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), was developed in this study. The PD-LVI UHPLC-MS/MS system was designed by slightly modifying the commercial UHPLC-MS/MS equipment with a mixer chamber. During the procedure of PD-LVI, sample solution of 200μL was directly carried by the organic mobile phase to the mixer and diluted with the aqueous mobile phase. After the mixture was introduced to the UHPLC column in a mobile phase of acetonitrile-water (15/85, v/v), the target analytes were stacked on the head of the column until following separation. Using QuEChERS extraction, no additional steps such as solvent evaporation or residue redissolution were needed before injection. The features of PD-LVI UHPLC-MS/MS system were systematically investigated, including the injection volume, the mixer volume, the precondition time and the gradient elution. The efficiency of this approach was demonstrated by direct analysis of 24 pesticides in cabbages. Under the optimized conditions, low limits of detection (0.00074-0.8 ng/kg) were obtained. The recoveries were in the range of 63.3-109% with relative standard deviations less than 8.1%. Compared with common UHPLC-MS/MS technique, PD-LVI UHPLC-MS/MS showed significant advantages such as excellent sensitivity and reliability. The mechanism of PD-LVI was demonstrated to be based on the column-head stacking effect with pre-column dilution. Based on the results, PD-LVI as a simple and effective sample injection technique of reverse phase UHPLC-MS/MS for the analysis of trace analytes in complex samples showed a great promising prospect. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Determination of trace sulfur in biodiesel and diesel standard reference materials by isotope dilution sector field inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Amais, Renata S. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, São Carlos, SP (Brazil); Long, Stephen E. [Chemical Sciences Division, National Institute of Standards and Technology, Charleston, SC (United States); Nóbrega, Joaquim A. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, São Carlos, SP (Brazil); Christopher, Steven J., E-mail: steven.christopher@nist.gov [Chemical Sciences Division, National Institute of Standards and Technology, Charleston, SC (United States)

    2014-01-02

    Graphical abstract: -- Highlights: •Sulfur mass fractions are measured below 10 mg kg{sup −1} in diesel fuel materials. •SF-ICP-MS resolves molecular interferences, including oxygen and sulfur hydrides. •A detection limit of 0.7 mg kg{sup −1} (in the fuel sample) was obtained. -- Abstract: A method is described for quantification of sulfur at low concentrations on the order of mg kg{sup −1} in biodiesel and diesel fuels using isotope dilution and sector field inductively coupled plasma mass spectrometry (ID-SF-ICP-MS). Closed vessel microwave-assisted digestion was employed using a diluted nitric acid and hydrogen peroxide decomposition medium to reduce sample dilution volumes. Medium resolution mode was employed to eliminate isobaric interferences at {sup 32}S and {sup 34}S related to polyatomic phosphorus and oxygen species, and sulfur hydride species. The method outlined yielded respective limits of detection (LOD) and limits of quantification (LOQ) of 0.7 mg kg{sup −1} S and 2.5 mg kg{sup −1} S (in the sample). The LOD was constrained by instrument background counts at {sup 32}S but was sufficient to facilitate value assignment of total S mass fraction in NIST SRM 2723b Sulfur in Diesel Fuel Oil at 9.06 ± 0.13 mg kg{sup −1}. No statistically significant difference at a 95% confidence level was observed between the measured and certified values for certified reference materials NIST SRM 2773 B100 Biodiesel (Animal-Based), CENAM DRM 272b and NIST SRM 2723a Sulfur in Diesel Fuel Oil, validating method accuracy.

  2. Flow injection on-line dilution for multi-element determination in human urine with detection by inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Wang, Jianhua; Hansen, Elo Harald; Gammelgaard, Bente

    2001-01-01

    A simple flow injection on-line dilution procedure with detection by inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of copper, zinc, arsenic, lead, selenium, nickel and molybdenum in human urine. Matrix effects were minimized by employing a dilution factor...... of 16.5 with on-line standard addition, and sup/ 103/Rh was used as internal standard to compensate for signal fluctuation. The procedure was validated by the analysis of two standard reference materials SRM 2670 (NIST) and Seronorm(TM) Trace Elements in Urine. Recovery experiments were performed...... by spiking the reference materials as well as artificial urine. The detection limits (mug/l were 0.12, 0.96, 0.30, 0.09, 0.45, 0.08, 0.09, and the precisions (RSD,%) were 2.6, 2.3, 3.0, 3.7, 3.7, 4.9, 2.8 for Cu, Zn, As, Pb, Se, Ni and Mo, respectively. The procedure was applied to the analysis of 41 human...

  3. Determination of the alkylpyrazine composition of coffee using stable isotope dilution-gas chromatography-mass spectrometry (SIDA-GC-MS).

    Science.gov (United States)

    Pickard, Stephanie; Becker, Irina; Merz, Karl-Heinz; Richling, Elke

    2013-07-03

    A stable isotope dilution analysis based on gas chromatography-mass spectrometry analysis (SIDA-GC-MS) was developed for the quantitative analysis of 12 alkylpyrazines found in commercially available coffee samples. These compounds contribute to coffee flavor. The accuracy of this method was tested by analyzing model mixtures of alkylpyrazines. Comparisons of alkylpyrazine-concentrations suggested that water as extraction solvent was superior to dichloromethane. The distribution patterns of alkylpyrazines in different roasted coffees were quite similar. The most abundant alkylpyrazine in each coffee sample was 2-methylpyrazine, followed by 2,6-dimethylpyrazine, 2,5-dimethylpyrazine, 2-ethylpyrazine, 2-ethyl-6-methylpyrazine, 2-ethyl-5-methylpyrazine, and 2,3,5-trimethylpyrazine, respectively. Among the alkylpyrazines tested, 2,3-dimethylpyrazine, 2-ethyl-3-methylpyrazine, 2-ethyl-3,6-dimethylpyrazine, and 2-ethyl-3,5-dimethylpyrazine revealed the lowest concentrations in roasted coffee. By the use of isotope dilution analysis, the total concentrations of alkylpyrazines in commercially available ground coffee ranged between 82.1 and 211.6 mg/kg, respectively. Decaffeinated coffee samples were found to contain lower amounts of alkylpyrazines than regular coffee samples by a factor of 0.3-0.7, which might be a result of the decaffeination procedure.

  4. Determination of Cd, Pb, Zn and Cu in Sediment Compartments by Sequential Extraction and Isotope Dilution Inductively Coupled Plasma Mass Spectrometry (ID-ICP-MS

    Directory of Open Access Journals (Sweden)

    Gardolinski Paulo C. F. C.

    2002-01-01

    Full Text Available Trace concentrations of Cd, Cu, Pb and Zn in four different sediment fractions extracted in sequence were determined by isotope dilution inductively coupled mass spectrometry (IDICPMS. The metals from each fraction were extracted following the sequential extraction procedure recommended by the Bureau Commun de Référence (BCR of the Commission of the European Communities. As an alternative to external calibration, the elements were quantified by spiking the extracted solutions with 112Cd, 63Cu, 208Pb and 66Zn and application of isotope dilution. The proposed approach was applied to a sample collected from a lake and two standard reference materials, NIST2704 river sediment from the National Institute of Standards & Technology and the BCR-277 estuarine sediment. Detection limits, for each extracted solution, varied from 0.31 to 0.53 mug L¹ for Cd, 0.92 to 2.9 mug L¹ for Cu, 0.22 to 1.1 mug L¹ for Pb and 1.3 to 7.6 mug L¹ for Zn. The sum of the metals concentration in the different fractions was compatible with 95% confidence level found amounts obtained with complete digestion of the samples and with the certified values of the standard reference materials.

  5. Flow injection on-line dilution for multi-element determination in human urine with detection by inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Wang, J.H.; Hansen, E.H.; Gammelgaard, Bente

    2001-01-01

    A simple flow injection on-line dilution procedure with detection by inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of copper, zinc, arsenic, lead, selenium, nickel and molybdenum in human urine. Matrix effects were minimized by employing a dilution fact...... of 16.5 with on-line standard addition, and Rh-103 was used as internal standard to compensate for signal fluctuation. The procedure was validated by the analysis of two standard reference materials SRM 2670 (NIST) and Seronorm (TM) Trace Elements in Urine. Recovery experiments were pet......-formed by spiking the reference materials as well as artificial urine. The detection limits (mug l(-1)) were 0.12, 0.96, 0.30, 0.09, 0.45, 0.08, 0.09, and the precisions (RSD,%) were 2.6, 2.3, 3.0, 3.7, 3.7, 4.9, 2.8 for Cu, Zn, As, Pb, Se, Ni and Mo, respectively. The procedure was applied to the analysis of 41...... human urine samples. No correlations between the concentrations of the elements were observed. (C) 2001 Elsevier Science B.V. All rights reserved...

  6. Comparison of analytical methods used to determine 235U, 238U and 210Pb from sediment samples by alpha, beta and gamma spectrometry

    International Nuclear Information System (INIS)

    Vesterbacka, P.; Klemola, S.; Salahel-Din, K.

    2009-01-01

    An intercomparison of the methodology (alpha, beta and gamma spectrometry) used for 238 U, 235 U and 210 Pb determination was carried out based on 38 sediment samples. The activity range of the samples varied from 10-700 Bq/kg for 210 Pb, 1-35 Bq/kg for 235 U and 10-800 Bq/ kg for 238 U. Results obtained using the three methods were not statistically different at high activity levels, but agreement between the results decreased at lower sample activity levels. For 210 Pb, the smallest difference was found between alpha and gamma spectrometry. A good correlation between results from alpha and gamma spectrometry was observed over the whole activity range. In beta spectrometry, the results were slightly higher than those obtained by alpha or gamma spectrometry due to the impurity of 228 Ra. In 238 U analysis, good correspondence was observed between 238 U determined by gamma and alpha spectrometry, particularly at higher 238 U activity concentrations over 100 Bq/kg. In 235 U analysis, attention needs to be paid to interference from 226 Ra and its reduction. (author)

  7. Measurement of electro-sprayed 238 and 239+240 plutonium isotopes using 4π-alpha spectrometry. Application to environmental samples

    International Nuclear Information System (INIS)

    Charmoille-Roblot, M.

    1999-01-01

    A new protocol for plutonium deposition using the electro-spray technique coupled with 4π-α spectrometry is proposed to improve the detection limit, shorten the counting time. In order to increase the detection efficiency, it was proposed to measure 238 and 239+240 plutonium isotopes electro-sprayed deposit simultaneously on both sides of the source support, that must be as transparent as possible to alpha-emissions, in a two-alpha detectors chamber. A radiochemical protocol was adapted to electro-spray constraints and a very thin carbon foil was selected for 4π -alpha spectrometry. The method was applied to a batch of sediment samples and gave the same results as an electrodeposited source measured using conventional alpha spectrometry with a 25 % gain on counting time and 10 % on plutonium 238 detection limit. Validation and application of the technique have been made on reference samples. (author)

  8. Determination of 210Pb by direct gamma-ray spectrometry, beta counting via 210Bi and alpha-particle spectrometry via 210Po in coal, slag and ash samples from thermal power plant

    International Nuclear Information System (INIS)

    Seslak, Bojan; Vukanac, Ivana; Kandic, Aleksandar; Durasevic, Mirjana; Eric, Milic; Jevremovic, Aleksandar

    2017-01-01

    In order to compare three different techniques and estimate radiological impact, activity concentration of 210 Pb in coal, slag and ash samples from thermal power plant 'Nikola Tesla', Serbia, were measured, and results are presented in this study. Determination of 210 Pb was carried out in three ways: using HPGe gamma spectrometer and via in-growth of 210 Po and 210 Bi by alpha-particle spectrometry and proportional counting, respectively. The results obtained for three different techniques were compared. Statistical analysis and comparison of methods were carried out by combination of Z score and χ 2 statistical tests. Tests results, as well as values of measured activities concentrations obtained by alpha and gamma spectrometry, showed that gamma spectrometry is a valid alternative to time-consuming alpha spectrometry for low level activity measurements of 210 Pb. This remark is also valid even for gamma spectrometers with poor efficiency in low energy region. (author)

  9. Identification of odorants in wood of Calocedrus decurrens (Torr.) Florin by aroma extract dilution analysis and two-dimensional gas chromatography-mass spectrometry/olfactometry.

    Science.gov (United States)

    Schreiner, Linda; Loos, Helene M; Buettner, Andrea

    2017-06-01

    General emissions of volatile organic compounds from wood are well investigated, but only limited information is available on the odor-active substances contained therein. To close this gap, we aimed at specifically elucidating the odorous constituents of wood from incense cedar [Calocedrus decurrens (Torr.) Florin]; this material is commonly used for the production of a range of products such as pencils and interior accessories. Targeted odorant analysis requires specialized techniques combining modern odorant analytical tools with human-sensory evaluation. Following this concept, the odor profile of the wood sample was first evaluated by human-sensory analyses. Then, the most potent wood odorants were characterized by means of gas chromatography-olfactometry and ranked according to their odor potency via aroma extract dilution analysis. With use of this approach, more than 60 odorous substances were detected, and the 22 most potent odorants were successfully identified by gas chromatography-mass spectrometry/olfactometry and two-dimensional gas chromatography-mass spectrometry/olfactometry. Among the main odorants found were a series of terpenes, several degradation products of fatty acids, and a number of odorants with a phenolic core moiety. Five odorants are reported here for the first time as wood odorants, such as γ-octalactone and 3-phenylpropanoic acid; thymoquinone was demonstrated for the first time to have a pencil-like odor quality.

  10. Differential Mobility-Mass Spectrometry Double Spike Isotope Dilution Study of Release of β-Methylaminoalanine and Proteinogenic Amino Acids during Biological Sample Hydrolysis.

    Science.gov (United States)

    Beach, Daniel G; Kerrin, Elliott S; Giddings, Sabrina D; Quilliam, Michael A; McCarron, Pearse

    2018-01-08

    The non-protein amino acid β-methylamino-L-alanine (BMAA) has been linked to neurodegenerative disease and reported throughout the environment. Proposed mechanisms of bioaccumulation, trophic transfer and chronic toxicity of BMAA rely on the hypothesis of protein misincorporation. Poorly selective methods for BMAA analysis have led to controversy. Here, a recently reported highly selective method for BMAA quantitation using hydrophilic interaction liquid chromatography-differential mobility spectrometry-tandem mass spectrometry (HILIC-DMS-MS/MS) is expanded to include proteinogenic amino acids from hydrolyzed biological samples. For BMAA quantitation, we present a double spiking isotope dilution approach using D 3 -BMAA and 13 C 15 N 2 -BMAA. These methods were applied to study release of BMAA during acid hydrolysis under a variety of conditions, revealing that the majority of BMAA can be extracted along with only a small proportion of protein. A time course hydrolysis of BMAA from mussel tissue was carried out to assess the recovery of BMAA during sample preparation. The majority of BMAA measured by typical methods was released before a significant proportion of protein was hydrolyzed. Little change was observed in protein hydrolysis beyond typical hydrolysis times but the concentration of BMAA increased linearly. These findings demonstrate protein misincorporation is not the predominant form of BMAA in cycad and shellfish.

  11. Preparation of large-area sources with uniform layers for the spectrometry of alpha-emitting nuclides

    International Nuclear Information System (INIS)

    Biehl, R.; Paschke, M.; Pilwat, G.

    1999-01-01

    A procedure for the preparation of large-area sources with uniform layers for α-spectrometry for the large-area grid ionization chamber has been developed. It is based on the direct evaporation of a sample solution in the counting dish in the presence of an excess of a sublimable chemical compound like ammonium nitrate. In the course of evaporation this excess compound precipitates and thus avoids the formation of clusters during the further evaporation process. After dryness, the excess compound is removed from the source by sublimation. Samarium nitrate is added as an internal standard and the alpha-activity of the isotope 147 Sm is chosen to measure the counting efficiency due to self-absorption. Examples are presented of the application of large-area sources for α-spectrometry for the large-area grid ionization chamber. (author)

  12. Development of SI-traceable C-peptide certified reference material NMIJ CRM 6901-a using isotope-dilution mass spectrometry-based amino acid analyses.

    Science.gov (United States)

    Kinumi, Tomoya; Goto, Mari; Eyama, Sakae; Kato, Megumi; Kasama, Takeshi; Takatsu, Akiko

    2012-07-01

    A certified reference material (CRM) is a higher-order calibration material used to enable a traceable analysis. This paper describes the development of a C-peptide CRM (NMIJ CRM 6901-a) by the National Metrology Institute of Japan using two independent methods for amino acid analysis based on isotope-dilution mass spectrometry. C-peptide is a 31-mer peptide that is utilized for the evaluation of β-cell function in the pancreas in clinical testing. This CRM is a lyophilized synthetic peptide having the human C-peptide sequence, and contains deamidated and pyroglutamylated forms of C-peptide. By adding water (1.00 ± 0.01) g into the vial containing the CRM, the C-peptide solution in 10 mM phosphate buffer saline (pH 6.6) is reconstituted. We assigned two certified values that represent the concentrations of total C-peptide (mixture of C-peptide, deamidated C-peptide, and pyroglutamylated C-peptide) and C-peptide. The certified concentration of total C-peptide was determined by two amino acid analyses using pre-column derivatization liquid chromatography-mass spectrometry and hydrophilic chromatography-mass spectrometry following acid hydrolysis. The certified concentration of C-peptide was determined by multiplying the concentration of total C-peptide by the ratio of the relative area of C-peptide to that of the total C-peptide measured by liquid chromatography. The certified value of C-peptide (80.7 ± 5.0) mg/L represents the concentration of the specific entity of C-peptide; on the other hand, the certified value of total C-peptide, (81.7 ± 5.1) mg/L can be used for analyses that does not differentiate deamidated and pyroglutamylated C-peptide from C-peptide itself, such as amino acid analyses and immunochemical assays.

  13. Secondary ion mass spectrometry combined with alpha track detection for isotope abundance ratio analysis of individual uranium-bearing particles.

    Science.gov (United States)

    Esaka, Fumitaka; Magara, Masaaki

    2014-03-01

    Secondary ion mass spectrometry (SIMS) was used in combination with alpha track detection for the efficient analysis of uranium-bearing particles with higher (235)U abundances in environmental samples. A polycarbonate film containing particles was prepared and placed in contact with a CR-39 plastic detector. After exposure for 28 days, the detector was etched in a NaOH solution and each uranium-bearing particle was identified through observation of the alpha tracks recorded in the detector. A portion of the film containing each uranium-bearing particle was cut out and put onto a glassy carbon planchet. The films on the planchet were decomposed through plasma ashing for subsequent uranium abundance ratio analysis with SIMS. The alpha track-SIMS analysis of 10 uranium-bearing particles in a sample taken from a nuclear facility enabled n((235)U)/n((238)U) abundance ratios in the range 0.0072-0.25 to be detected, which were significantly higher than those obtained by SIMS without alpha track detection. The duration of the whole analytical process for analysis of 10 particles was about 32 days. The detection efficiency was calculated to be 27.1±6.5%, based on the analysis of the particles in uranium reference materials. The detection limits, defined as the diameter of the particle which produces alpha tracks more than one for a 28-days exposure, were estimated to be 0.8, 0.9, 1.1, 2.1 and 3.0 μm for the particles having the same uranium abundance ratios with NBL CRM U850, U500, U350, U050 and U010 reference materials, respectively. The use of alpha track detection for subsequent SIMS analysis is an inexpensive and an efficient way to measure uranium-bearing particles with higher (235)U abundances. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. DETERMINATION OF MUSHROOM TOXIN ALPHA-AMANITIN IN SERUM BY LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY AFTER SOLID-PHASE EXTRACTION

    Directory of Open Access Journals (Sweden)

    Maja Vujović

    2015-03-01

    Full Text Available Alpha-amanitin is a cyclic peptide which belongs to a large group of mushroom toxins known as amatoxins. Being responsible for the majority of fatal mushroom poisonings, they require rapid detection and excretion from the body fluids. In accordance with these requirements, a simple and an accurate method was developed for successful identification and quantification of alpha-amanitin in serum with electrospray liquid chromatography–mass spectrometry (LC-ESI-MS after collision-induced dissociation. The method conforms to the established International Conference on Harmonization Q2A/Q2B 1996 guidelines on the validation of analytical methods. Linearity, precision, extraction recovery and stability test on blank serum spiked with alpha-amanitin and stored in different conditions met the acceptance criteria. The obtained calibration curve was linear over the concentration range 5-100 ng/mL with a lower limit of quantification (LOQ of 5 ng/mL and limit of detection (LOD of 2.5 ng/mL. The mean intra- and inter-day precision and accuracy were 6.05% and less than ±15% of nominal values, respectively. The neutral solid phase extraction with copolymer hydrophilic–lipophilic balance cartridges was found optimal for sample preparation with the mean recovery of 91.94%. The proposed method demonstrated high sensitivity and selectivity which can be useful both for clinical and forensic toxicology analysis of alpha-amanitin at low concentrations.

  15. Alternate method of source preparation for alpha spectrometry: no electrodeposition, no hydrofluoric acid

    International Nuclear Information System (INIS)

    Hiromu Kurosaki; Lambert, S.B.; Rao, G.R.; Mueller, R.J.

    2017-01-01

    An alternate method of preparing actinide alpha counting sources was developed in place of electrodeposition or lanthanide fluoride micro-precipitation. The method uses lanthanide hydroxide micro-precipitation to avoid the use of hazardous hydrofluoric acid. It provides a quicker, simpler, and safer way of preparing actinide alpha counting sources in routine, production-type laboratories that process many samples daily. (author)

  16. Alternate method of source preparation for alpha spectrometry: No electrodeposition, no hydrofluoric acid

    International Nuclear Information System (INIS)

    Kurosaki, Hiromu; Mueller, Rebecca J.; Lambert, Susan B.; Rao, Govind R.

    2016-01-01

    An alternate method of preparing actinide alpha counting sources was developed in place of electrodeposition or lanthanide fluoride micro-precipitation. The method uses lanthanide hydroxide micro-precipitation to avoid the use of hazardous hydrofluoric acid. Lastly, it provides a quicker, simpler, and safer way of preparing actinide alpha counting sources in routine, production-type laboratories that process many samples daily.

  17. Comparative determination of uranium in rock phosphates and columbite by ICP-OES, alpha and gamma spectrometry

    International Nuclear Information System (INIS)

    Singhal, R.K.; Sharma, P.K.; Bassan, M.K.T.; Basu, H.; Reddy, A.V.R.

    2011-01-01

    During this work selective separation of uranium from rock phosphate and columbite mineral was done before its quantitative estimation by using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Uranium from the rock phosphate and columbite was extracted by sodium peroxide fusion followed by leaching in 2 M HNO 3 . To avoid spectral interference in the estimation of uranium by ICP-OES, the selective separation of uranium from the leachate was carried out by using two different extractants, 30% Tributyl Phosphates (TBP) in CCl 4 and a equi-volume mixture of Di(2-ethylhexyl) phosphoric acid (D2EHPA) and TBP in petrofin. Uranium was stripped from the organic phase by using 1 M ammonium carbonate solution. Determination of uranium by ICP-OES was done after dissolving the residue left after evaporation of ammonium carbonate solution in 4% HNO 3 . The concentration of the uranium observed in the rock phosphates samples was 40-200 μg g -1 whereas in columbite samples the concentration range was 100-600 μg g -1 . Uranium concentration evaluated by ICP-OES was complimented by gamma and alpha spectrometry. Concentration of uranium evaluated by gamma spectrometry in case of rock phosphate and columbite was in close agreement with the uranium content obtained by ICP-OES. Uranium determination by alpha spectrometry showed only minor deviation (1-2%) from the results obtained by ICP-OES in case of rock phosphates whereas in case of columbites results are off by 20-30%. (author)

  18. Chemical vapor deposition (CVD) of uranium for alpha spectrometry; Deposicion quimica de vapor (CVD) de uranio para espectrometria alfa

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez V, M. L.; Rios M, C.; Ramirez O, J.; Davila R, J. I.; Mireles G, F., E-mail: luisalawliet@gmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2015-09-15

    The uranium determination through radiometric techniques as alpha spectrometry requires for its proper analysis, preparation methods of the source to analyze and procedures for the deposit of this on a surface or substrate. Given the characteristics of alpha particles (small penetration distance and great loss of energy during their journey or its interaction with the matter), is important to ensure that the prepared sources are thin, to avoid problems of self-absorption. The routine methods used for this are the cathodic electro deposition and the direct evaporation, among others. In this paper the use of technique of chemical vapor deposition (CVD) for the preparation of uranium sources is investigated; because by this, is possible to obtain thin films (much thinner than those resulting from electro deposition or evaporation) on a substrate and comprises reacting a precursor with a gas, which in turn serves as a carrier of the reaction products to achieve deposition. Preliminary results of the chemical vapor deposition of uranium are presented, synthesizing and using as precursor molecule the uranyl acetylacetonate, using oxygen as carrier gas for the deposition reaction on a glass substrate. The uranium films obtained were found suitable for alpha spectrometry. The variables taken into account were the precursor sublimation temperatures and deposition temperature, the reaction time and the type and flow of carrier gas. Of the investigated conditions, two depositions with encouraging results that can serve as reference for further work to improve the technique presented here were selected. Alpha spectra obtained for these depositions and the characterization of the representative samples by scanning electron microscopy and X-ray diffraction are also presented. (Author)

  19. Isotope dilution/mass spectrometry of serum cholesterol with [3,4-13C]cholesterol: proposed definitive method

    International Nuclear Information System (INIS)

    Pelletier, O.; Wright, L.A.; Breckenridge, W.C.

    1987-01-01

    We describe a new gas-chromatographic/mass-spectrometric (GC/MS) isotope-dilution method for determination of serum cholesterol. The method has been fully optimized and documented to provide the high accuracy and precision expected for a Definitive Method. In the presence of [3,4- 13 C]cholesterol, cholesteryl esters in serum are hydrolyzed under optimum conditions and the entire cholesterol pool is extracted and derivatized to silyl ethers. The cholesterol derivatives are resolved from other sterols by gas-liquid chromatography on a fused silica column, and selected ions characteristic of cholesterol and the [3,4- 13 C]cholesterol are monitored with a GC/MS quandrupole system. We estimated the cholesterol content of samples by bracketing each sample with standards of comparable cholesterol concentration that also contained the [3,4- 13 C]cholesterol. The procedure was highly reproducible (CV less than 0.5%), better accuracy and precision being obtained with [3,4- 13 C]cholesterol than with heptadeuterated cholesterol. Mean values per gram of dry serum for one serum pool assayed by this method and that of the National Bureau of Standards differed by 0.5%. We conclude that the method satisfies the criteria for a Definitive Method

  20. Contents of selected B vitamins in NIST SRM 3280 multivitamin/multielement tablets by liquid chromatography isotope dilution mass spectrometry.

    Science.gov (United States)

    Chen, Pei; Ozcan, Mustafa; Wolf, Wayne R

    2007-09-01

    There is increased interest in accurately assessing the total dietary intake of vitamins from all sources, including foods and dietary supplements. Consequently, a Dietary Supplement Ingredient Database (DSID), based upon analytical values, is being established by USDA with support of the Office of Dietary Supplements (ODS), NIH. The DSID necessitated the development of a new SRM, 3280--Multivitamin/Multimineral Tablets, by the National Institute of Standards and Technology (NIST), with support from the ODS. As a continuation of a long-term project to develop and validate new methods of determining water-soluble B vitamins in foods and dietary supplements, and as part of a collaborative effort with NIST to characterize SRM 3280, values for the vitamin contents of SRM 3280 have been generated by a liquid chromatographic isotope dilution mass spectrometric (LC/IDMS) method. Isotope-labeled ((13)C and/or (2)H) B vitamins (B1-thiamine, B6-pyridoxine, B3-nicotinamide, and B5-pantothenic acid) were obtained from commercial sources, with the support of the ODS/NIH. Our LC/IDMS method uses a C18 reversed phase column, an Agilent 1100 HPLC system, and a Quattro Micro triple-quad mass spectrometer (MS). B vitamin determination was achieved using a gradient LC profile combined with MS/MS detection in multiple reaction monitoring mode. Stock solutions of the isotope-labeled vitamins were calibrated against USP standard solutions. The SRM tablets, with added amounts of the four isotope-labeled B vitamins, were extracted and the vitamins simultaneously determined in a single LC run, in contrast with the single-component determinations performed via IDMS. Unknown vitamin concentrations were calculated by comparing the ratios of the integrated LC peaks at the different masses of the unlabeled and labeled vitamins.

  1. Accurate determination of selected pesticides in soya beans by liquid chromatography coupled to isotope dilution mass spectrometry.

    Science.gov (United States)

    Huertas Pérez, J F; Sejerøe-Olsen, B; Fernández Alba, A R; Schimmel, H; Dabrio, M

    2015-05-01

    A sensitive, accurate and simple liquid chromatography coupled with mass spectrometry method for the determination of 10 selected pesticides in soya beans has been developed and validated. The method is intended for use during the characterization of selected pesticides in a reference material. In this process, high accuracy and appropriate uncertainty levels associated to the analytical measurements are of utmost importance. The analytical procedure is based on sample extraction by the use of a modified QuEChERS (quick, easy, cheap, effective, rugged, safe) extraction and subsequent clean-up of the extract with C18, PSA and Florisil. Analytes were separated on a C18 column using gradient elution with water-methanol/2.5 mM ammonium acetate mobile phase, and finally identified and quantified by triple quadrupole mass spectrometry in the multiple reaction monitoring mode (MRM). Reliable and accurate quantification of the analytes was achieved by means of stable isotope-labelled analogues employed as internal standards (IS) and calibration with pure substance solutions containing both, the isotopically labelled and native compounds. Exceptions were made for thiodicarb and malaoxon where the isotopically labelled congeners were not commercially available at the time of analysis. For the quantification of those compounds methomyl-(13)C2(15)N and malathion-D10 were used respectively. The method was validated according to the general principles covered by DG SANCO guidelines. However, validation criteria were set more stringently. Mean recoveries were in the range of 86-103% with RSDs lower than 8.1%. Repeatability and intermediate precision were in the range of 3.9-7.6% and 1.9-8.7% respectively. LODs were theoretically estimated and experimentally confirmed to be in the range 0.001-0.005 mg kg(-1) in the matrix, while LOQs established as the lowest spiking mass fractionation level were in the range 0.01-0.05 mg kg(-1). The method reliably identifies and quantifies the

  2. Measurement of electro-sprayed 238 and 239+240 plutonium isotopes using 4{pi}-alpha spectrometry. Application to environmental samples; Spectrometrie alpha 4{pi} de sources d'actinides realisees par electronebulisation. Developpement et optimisation d'un protocole applique au mesurage des isotopes 238 et 239+240 du plutonium dans l'environnement

    Energy Technology Data Exchange (ETDEWEB)

    Charmoille-Roblot, M. [CEA/Fontenay-aux-Roses, Dept. de Protection de l' Environnement (DPRE), 92 (France)]|[Paris-11 Univ., 91 - Orsay (France)

    1999-07-01

    A new protocol for plutonium deposition using the electro-spray technique coupled with 4{pi}-{alpha} spectrometry is proposed to improve the detection limit, shorten the counting time. In order to increase the detection efficiency, it was proposed to measure 238 and 239+240 plutonium isotopes electro-sprayed deposit simultaneously on both sides of the source support, that must be as transparent as possible to alpha-emissions, in a two-alpha detectors chamber. A radiochemical protocol was adapted to electro-spray constraints and a very thin carbon foil was selected for 4{pi} -alpha spectrometry. The method was applied to a batch of sediment samples and gave the same results as an electrodeposited source measured using conventional alpha spectrometry with a 25 % gain on counting time and 10 % on plutonium 238 detection limit. Validation and application of the technique have been made on reference samples. (author)

  3. Phosphoinositide binding regulates alpha-actinin CH2 domain structure: analysis by hydrogen/deuterium exchange mass spectrometry.

    Science.gov (United States)

    Full, Stephen J; Deinzer, Max L; Ho, P Shing; Greenwood, Jeffrey A

    2007-12-01

    alpha-Actinin is an actin bundling protein that regulates cell adhesion by directly linking actin filaments to integrin adhesion receptors. Phosphatidylinositol (4,5)-diphosphate (PtdIns (4,5)-P(2)) and phosphatidylinositol (3,4,5)-triphosphate (PtdIns (3,4,5)-P(3)) bind to the calponin homology 2 domain of alpha-actinin, regulating its interactions with actin filaments and integrin receptors. In this study, we examine the mechanism by which phosphoinositide binding regulates alpha-actinin function using mass spectrometry to monitor hydrogen-deuterium (H/D) exchange within the calponin homology 2 domain. The overall level of H/D exchange for the entire protein showed that PtdIns (3,4,5)-P(3) binding alters the structure of the calponin homology 2 domain increasing deuterium incorporation, whereas PtdIns (4,5)-P(2) induces changes in the structure decreasing deuterium incorporation. Analysis of peptic fragments from the calponin homology 2 domain showed decreased local H/D exchange within the loop region preceding helix F with both phosphoinositides. However, the binding of PtdIns (3,4,5)-P(3) also induced increased exchange within helix E. This suggests that the phosphate groups on the fourth and fifth position of the inositol head group of the phosphoinositides constrict the calponin homology 2 domain, thereby altering the orientation of actin binding sequence 3 and decreasing the affinity of alpha-actinin for filamentous actin. In contrast, the phosphate group on the third position of the inositol head group of PtdIns (3,4,5)-P(3) perturbs the calponin homology 2 domain, altering the interaction between the N and C terminus of the full-length alpha-actinin antiparallel homodimer, thereby disrupting bundling activity and interaction with integrin receptors.

  4. Validation of an isotope dilution gas chromatography-mass spectrometry method for combined analysis of oxysterols and oxyphytosterols in serum samples.

    Science.gov (United States)

    Schött, Hans-Frieder; Lütjohann, Dieter

    2015-07-01

    We describe the validation of a method for the analysis of oxysterols, i.e. oxycholesterols and oxyphytosterols, in human serum using gas chromatography-mass spectrometry selected ion monitoring (GC-MS-SIM). Concentrations of 7α- and 7β-hydroxy-, and 7oxo-cholesterol, -campesterol, and -sitosterol as well as 4β-hydroxycholesterol and side-chain oxygenated 24S-, 25-, and 27-hydroxycholesterol were determined by isotope dilution methodology. After saponification at room temperature the oxysterols were extracted, separated from their substrates, cholesterol, campesterol, and sitosterol, by solid phase extraction, and subsequently derivatised to their corresponding trimethylsilyl-ethers prior to GC-MS-SIM. In order to prevent artificial autoxidation butylated hydroxytoluene and ethylenediaminetetraacetic acid were added. The validation of the method was performed according to the International Conference on Harmonisation guidance, including limits of detection and quantification, ranges, recovery and precision. Due to improved instrumental settings and work-up procedure, limits of detection and quantification ranged between 8.0-202.0pg/mL and 28.0-674pg/mL, respectively. Recovery data in five calibration points varied between 91.9% and 116.8% and in serum samples between 93.1% and 118.1%. The mean coefficient of variation (CV) for the recovery of all compounds was <10%. Well satisfying CVs for within-day precision (2.1-10.8%) and for between-day precision (2.3-12.1%) were obtained. More than 20 samples could be processed in a single routine day and test series of about 300 samples can be realised without impairment of the validation parameters during a sequence. Comparison of oxysterol and oxyphytosterol content in serum and plasma revealed no difference. A fully validated isotope dilution methodology for the quantification of oxycholesterols and oxyphytosterols from human serum or plasma is presented. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Exploiting dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) for sequential determination of trace elements in blood using a dilute-and-shoot procedure

    International Nuclear Information System (INIS)

    Lemos Batista, Bruno; Lisboa Rodrigues, Jairo; Andrade Nunes, Juliana; Oliveira Souza, Vanessa Cristina de; Barbosa, Fernando

    2009-01-01

    Inductively coupled plasma mass spectrometry with quadrupole (q-ICP-MS) and dynamic reaction cell (DRC-ICP-MS) were evaluated for sequential determination of As, Cd, Co, Cr, Cu, Mn, Pb, Se, Tl, V and Zn in blood. The method requires as little as 100 μL of blood. Prior to analysis, samples (100 μL) were diluted 1:50 in a solution containing 0.01% (v/v) Triton X-100 and 0.5% (v/v) nitric acid. The use of the DRC was only mandatory for Cr, Cu, V and Zn. For the other elements the equipment may be operated in a standard mode (q-ICP-MS). Ammonia was used as reaction gas. Selection of best flow rate of ammonium gas and optimization of the quadrupole dynamic band-pass tuning parameter (RPq) were carried out, using a ovine base blood for Cr and V and a synthetic matrix solution (SMS) for Zn and Cu diluted 1:50 and spiked to contain 1 μg L -1 of each element. Method detection limits (3 s) for 75 As, 114 Cd, 59 Co, 51 Cr, 63 Cu 55 Mn, 208 Pb, 82 Se, 205 Tl, 51 V, and 64 Zn were 14.0, 3.0, 11.0, 7.0, 280, 9.0, 3.0, 264, 0.7, 6.0 and 800 ng L -1 , respectively. Method validation was accomplished by the analysis of blood Reference Materials produced by the L'Institut National de Sante Publique du Quebec (Canada).

  6. Quantification of abscisic acid in grapevine leaf (Vitis vinifera) by isotope-dilution liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Vilaró, Francisca; Canela-Xandri, Anna; Canela, Ramon

    2006-09-01

    A specific, sensitive, precise, and accurate method for the determination of abscisic acid (ABA) in grapevine leaf tissues is described. The method employs high-performance liquid chromatography and electrospray ionization-mass spectrometry (LC-ESI-MS) in selected ion monitoring mode (SIM) to analyze ABA using a stable isotope-labeled ABA as an internal standard. Absolute recoveries ranged from 72% to 79% using methanol/water pH 5.5 (50:50 v/v) as an extraction solvent. The best efficiency was obtained when the chromatographic separation was carried out by using a porous graphitic carbon (PGC) column. The statistical evaluation of the method was satisfactory in the work range. A relative standard deviation (RDS) of < 5.5% and < 6.0% was obtained for intra-batch and inter-batch comparisons, respectively. As for accuracy, the relative error (%Er) was between -2.7 and 4.3%, and the relative recovery ranged from 95% to 107%.

  7. Liquid chromatography with isotope-dilution mass spectrometry for determination of water-soluble vitamins in foods.

    Science.gov (United States)

    Phillips, Melissa M

    2015-04-01

    Vitamins are essential for improving and maintaining human health, and the main source of vitamins is the diet. Measurement of the quantities of water-soluble vitamins in common food materials is important to understand the impact of vitamin intake on human health, and also to provide necessary information for regulators to determine adequate intakes. Liquid chromatography (LC) and mass spectrometry (MS) based methods for water-soluble vitamin analysis are abundant in the literature, but most focus on only fortified foods or dietary supplements or allow determination of only a single vitamin. In this work, a method based on LC/MS and LC/MS/MS has been developed to allow simultaneous quantitation of eight water-soluble vitamins, including multiple forms of vitamins B3 and B6, in a variety of fortified and unfortified food-matrix Standard Reference Materials (SRMs). Optimization of extraction of unbound vitamin forms and confirmation using data from external laboratories ensured accuracy in the assigned values, and addition of stable isotope labeled internal standards for each of the vitamins allowed for increased precision.

  8. The measurement of the isotope ratios and concentrations of zinc by thermal ionization mass spectrometry using double isotope dilution

    International Nuclear Information System (INIS)

    Deng Zhongguo

    1994-01-01

    The isotope ratios and concentrations of zinc are measured by silicagel-thermal ionization mass spectrometry using the double isotope spikers. The double isotope spikers ( 70 Zn and 67 Zn-enriched isotopes) are used to correct the isotope mass fractionation for the zinc isotope ratios, and to certify the zinc concentrations in the unknown samples. The zinc concentrations of these double isotope spikers are surveyed by a spiker made of pure (99.99%) natural zinc metal powder. The correcting factors (f a , f t and f n ) of the zinc isotope ratios in the spiked mixture, spike and unspiked samples for the isotope mass fractionation, and the spike-to-unspiked ratios (X r ) of the zinc isotope r in the spiked mixture samples can be obtained to solve the matrix equations by numerical approximation. The natural zinc isotope ratios are: 64 Zn/ 67 Zn = 11.8498, 66 Zn/ 67 Zn = 6.7977, 68 Zn/ 67 Zn = 4.5730 and 70 Zn/ 67 Zn = 0.1520. The uncertainties determined of the isotope ratios and concentrations of zinc are +- 0.16% and +-0.31%, respectively

  9. Nuclear Track Detector Characterization via Alpha-Spectrometry for Radioprotection Use

    Energy Technology Data Exchange (ETDEWEB)

    Morelli, D.; Imme, G.; Catalano, R. [Dipartimento di Fisica e Astronomia, Universita degli Studi di Catania, via S. Sofia, 64- 95123 Catania (Italy); Istituto Nazionale di Fisica Nucleare - Sezione di Catania, via S. Sofia, 64- 95123 Catania (Italy); Aranzulla, M. [Istituto Nazionale Geofisica e Vulcanologia - Sezione di Catania, piazza Roma, 2- 95127 Catania (Italy); Tazzer, A. L. Rosselli; Mangano, G. [Dipartimento di Fisica e Astronomia, Universita degli Studi di Catania, via S. Sofia, 64- 95123 Catania (Italy)

    2011-12-13

    Solid Nuclear Track Detectors (SNTDs), CR-39 type, are usually adopted to monitor radon gas concentrations. In order to characterize the detectors according to track geometrical parameters, detectors were irradiated inside a vacuum chamber by alpha particles at twelve energy values, obtained by different Mylar foils in front of a {sup 241}Am source. The alpha energy values were verified using a Si detector. After the exposure to the alpha particles, the detectors were chemically etched to enlarge the tracks, which were then analyzed by means of a semiautomatic system composed of an optical microscope equipped with a CCD camera connected to a personal computer to store images. A suitable routine analyzed the track parameters: major and minor axis length and mean grey level, allowing us to differentiate tracks according to the incident alpha energy and then to individuate the discrimination factors for radon alpha tracks. The combined use of geometrical and optical parameters allows one to overcome the ambiguity in the alpha energy determination due to the non-monotonicity of each parameter versus energy. After track parameter determination, a calibration procedure was performed by means of a radon chamber. The calibration was verified through an inter-comparing survey.

  10. Simultaneous analysis of polychlorinated biphenyls and polychlorinated naphthalenes by isotope dilution comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry.

    Science.gov (United States)

    Xia, Dan; Gao, Lirong; Zheng, Minghui; Wang, Shasha; Liu, Guorui

    2016-09-21

    Polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) are listed as persistent organic pollutants (POPs) under the Stockholm Convention. Because they have similar physical and chemical properties, they are coeluted and are usually analyzed separately by different gas chromatography high-resolution mass spectrometry (GC-HRMS) methods. In this study, a novel method was developed for simultaneous analysis of six indicator PCBs, 12 dioxin-like PCBs, and 16 PCNs using isotope dilution comprehensive two-dimensional gas chromatography with high-resolution time-of-flight mass spectrometry (GC × GC-HRTOF-MS). The method parameters, including the type of GC column, oven temperature program, and modulation period, were systematically optimized. Complete separation of all target analytes and the matrix was achieved with a DB-XLB column in the first dimension and a BPX-70 column in the second dimension. The isotope dilution method was used for quantification of the PCBs and PCNs by GC × GC-HRTOF-MS. The method showed good linearity from 5 to 500 pg μL(-1) for all the target compounds. The instrumental limit of detection ranged from 0.03 to 0.3 pg μL(-1) for the 18 PCB congeners and from 0.09 to 0.6 pg μL(-1) for the 16 PCN congeners. Repeatability for triplicate injections was always lower than 20%. The method was successfully applied to the determination of 18 PCBs present at 0.9-2054 pg g(-1) and 16 PCNs present at 0.2-15.7 pg g(-1) in three species of fish. The GC × GC-HRTOF-MS results agreed with those obtained by GC-HRMS. The GC × GC-HRTOF-MS method proved to be a sensitive and accurate technique for simultaneous analysis of the selected PCBs and PCNs. With the excellent chromatographic separation offered by GC × GC and accurate mass measurements offered by HRTOF-MS, this method allowed identification of non-target contaminants in the fish samples, including organochlorine pesticides and polycyclic aromatic hydrocarbons

  11. Quantitative Isotope-Dilution High-Resolution-Mass-Spectrometry Analysis of Multiple Intracellular Metabolites in Clostridium autoethanogenum with Uniformly 13C-Labeled Standards Derived from Spirulina.

    Science.gov (United States)

    Schatschneider, Sarah; Abdelrazig, Salah; Safo, Laudina; Henstra, Anne M; Millat, Thomas; Kim, Dong-Hyun; Winzer, Klaus; Minton, Nigel P; Barrett, David A

    2018-04-03

    We have investigated the applicability of commercially available lyophilized spirulina ( Arthrospira platensis), a microorganism uniformly labeled with 13 C, as a readily accessible source of multiple 13 C-labeled metabolites suitable as internal standards for the quantitative determination of intracellular bacterial metabolites. Metabolites of interest were analyzed by hydrophilic-interaction liquid chromatography coupled with high-resolution mass spectrometry. Multiple internal standards obtained from uniformly (U)- 13 C-labeled extracts from spirulina were used to enable isotope-dilution mass spectrometry (IDMS) in the identification and quantification of intracellular metabolites. Extraction of the intracellular metabolites of Clostridium autoethanogenum using 2:1:1 chloroform/methanol/water was found to be the optimal method in comparison with freeze-thaw, homogenization, and sonication methods. The limits of quantification were ≤1 μM with excellent linearity for all of the calibration curves ( R 2 ≥ 0.99) for 74 metabolites. The precision and accuracy were found to be within relative standard deviations (RSDs) of 15% for 49 of the metabolites and within RSDs of 20% for all of the metabolites. The method was applied to study the effects of feeding different levels of carbon monoxide (as a carbon source) on the central metabolism and Wood-Ljungdahl pathway of C. autoethanogenum grown in continuous culture over 35 days. Using LC-IDMS with U- 13 C spirulina allowed the successful quantification of 52 metabolites in the samples, including amino acids, carboxylic acids, sugar phosphates, purines, and pyrimidines. The method provided absolute quantitative data on intracellular metabolites that was suitable for computational modeling to understand and optimize the C. autoethanogenum metabolic pathways active in gas fermentation.

  12. Analysis of zearalenone and alpha-zearalenol in urine of ruminants using gas chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Plasencia, J; Mirocha, C J; Pawlosky, R J; Smith, J F

    1990-01-01

    The present paper describes a sensitive procedure for quantitative analysis of the Fusarium mycotoxins zearalenone and alpha-zearalenol in urine of ruminants. Extraction is done with an octadecyl (C18) column and cleanup with a silica column providing a preparation that is analyzed by gas chromatography-tandem mass spectrometry (GC-MS/MS). The trimethylsilyl ether derivatives of zearalenone and alpha-zearalenol yield molecular ions with m/z 462 and 536, respectively. These ions are selected in the first mass analyzer and then fragmented in a collision cell to give characteristic daughter ions (m/z 151, 333, 318, and 446). The method is known as multiple reaction monitoring (MRM). Elimination of chemical background noise by selecting proper fragment ions produces chromatograms in which identification and quantitation in a biological matrix is possible. The method was tested with sheep urine from an experimental feeding trial and was used to confirm natural mycotoxicosis of cows affected with zearalenone. Zearalenone (1 ppb) and alpha-zearalenol (14 ppb) were found in 2 different cow urine samples. The detection limit for both zearalenone and zearalenol is 1 ppb (1 ng/mL) in urine and is linear between 1 and 20 ppb for the former and 1 and 10 ppb for the latter.

  13. Functional unfolding of alpha1-antitrypsin probed by hydrogen-deuterium exchange coupled with mass spectrometry.

    Science.gov (United States)

    Baek, Je-Hyun; Yang, Won Suk; Lee, Cheolju; Yu, Myeong-Hee

    2009-05-01

    The native state of alpha(1)-antitrypsin (alpha(1)AT), a member of the serine protease inhibitor (serpin) family, is considered a kinetically trapped folding intermediate that converts to a more stable form upon complex formation with a target protease. Although previous structural and mutational studies of alpha(1)AT revealed the structural basis of the native strain and the kinetic trap, the mechanism of how the native molecule overcomes the kinetic barrier to reach the final stable conformation during complex formation remains unknown. We hypothesized that during complex formation, a substantial portion of the molecule undergoes unfolding, which we dubbed functional unfolding. Hydrogen-deuterium exchange coupled with ESI-MS was used to analyze this serpin in three forms: native, complexing, and complexed with bovine beta-trypsin. Comparing the deuterium content at the corresponding regions of these three samples, we probed the unfolding of alpha(1)AT during complex formation. A substantial portion of the alpha(1)AT molecule unfolded transiently during complex formation, including not only the regions expected from previous structural studies, such as the reactive site loop, helix F, and the following loop, but also regions not predicted previously, such as helix A, strand 6 of beta-sheet B, and the N terminus. Such unfolding of the native interactions may elevate the free energy level of the kinetically trapped native serpin sufficiently to cross the transition state during complex formation. In the current study, we provide evidence that protein unfolding has to accompany functional execution of the protein molecule.

  14. Identification of a Rare Hemoglobin Variant HbJ-Rajappen [alpha90 (FG2) Lys → Thr] Using Mass Spectrometry.

    Science.gov (United States)

    Bhat, Vijay S; Mandal, Amit Kumar; Mathew, Bobby

    2012-10-01

    Hemoglobin J-Rajappen (alpha)90 Lys → Thr is an alpha chain variant found in heterozygous state and presents normal hematological blood picture. Due to the ambiguity in results obtained while analyzing by HPLC and alkaline gel electrophoresis, we report this rare case of HbJ-Rajappen using non denaturing gel electrophoresis and matrix assisted laser desorption ionization mass spectrometry. Though HbJ-Rajappen has earlier been reported using different techniques, this is the first report being validated using mass spectrometry technique.

  15. Detection of triclocarban and two co-contaminating chlorocarbanilides in US aquatic environments using isotope dilution liquid chromatography tandem mass spectrometry

    International Nuclear Information System (INIS)

    Sapkota, Amir; Heidler, Jochen; Halden, Rolf U.

    2007-01-01

    The antimicrobial compound triclocarban (TCC; 3,4,4'-trichlorocarbanilide; CAS-bar 101-20-2) is a high-production-volume chemical, recently suggested to cause widespread contamination of US water resources. To test this hypothesis, we developed an isotope dilution liquid chromatography electrospray ionization tandem mass spectrometry method for ultratrace analysis of TCC (0.9ng/L detection limit) and analyzed low-volume water samples (200mL) along with primary sludge samples from across the United States. All river water samples (100%) collected downstream of wastewater treatment plants had detectable levels of TCC, as compared to 56% of those taken upstream. Concentrations of TCC (mean+/-standard deviation) downstream of sewage treatment plants (84+/-110ng/L) were significantly higher (P w/w each) in technical grade TCC (99%). Application of the new method for chlorocarbanilide analysis yielded TCC occurrence data for 13 US states, confirmed the role of sewage treatment plants as environmental inputs of TCC, and identified DCC and TetraCC as previously unrecognized pollutants released into the environment alongside TCC

  16. Regional water-quality analysis of 2,4-D and dicamba in river water using gas chromatography-isotope dilution mass spectrometry

    Science.gov (United States)

    Thurman, E.M.; Zimmerman, L.R.; Aga, D.S.; Gilliom, R.J.

    2001-01-01

    Gas chromatography with isotope dilution mass spectrometry (GC-MS) and enzyme-linked immunosorbent assay (ELISA) were used in regional National Water Quality Assessment studies of the herbicides, 2,4-D and dicamba, in river water across the United States. The GC-MS method involved solid-phase extraction, derivatized with deutemted 2,4-D, and analysis by selected ion monitoring. The ELISA method was applied after preconcentration with solid-phase extraction. The ELISA method was unreliable because of interference from humic substances that were also isolated by solid-phase extraction. Therefore, GC-MS was used to analyzed 80 samples from river water from 14 basins. The frequency of detection of dicamba (28%) was higher than that for 2,4-D (16%). Concentrations were higher for dicamba than for 2,4-D, ranging from less than the detection limit (of 5 times more annual use of 2,4-D as compared to dicamba. These results suggest that 2,4-D degrades more rapidly in the environment than dicamba.

  17. Simultaneous determination of Δ9-tetrahydrocannabinol and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol in oral fluid using isotope dilution liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Lee, Pin Duo; Chang, Yuan-Jhe; Lin, Keh-Liang; Chang, Yan-Zin

    2012-01-01

    The detection and confirmation of cannabinoids in oral fluid are important in forensic toxicology. Currently, the presence of Δ(9)-tetrahydrocannabinol (THC) is used for the detection of cannabis in oral fluid. A low concentration of 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol (THC-COOH) is found in oral fluid, which suggested a convenient and low-sensitivity confirmation assay can be used in a routine forensic laboratory. In this study, a highly sensitive isotope dilution liquid chromatography-tandem mass spectrometry method following dansylation was successfully developed for simultaneous determination of THC and THC-COOH in oral fluid. The dansylated derivatives dramatically demonstrated and enhanced the sensitivity of THC and THC-COOH. To avoid signal influenced by the matrix, a 5-min liquid chromatography gradient program was evaluated and optimized, which reduced the sample diffusion and caused sharp peaks (less than 12 s) and thus helped to achieve detection at a low level. The sensitivity, accuracy, and precision were also evaluated, and high quantitative accuracy and precision were obtained. The limit of quantitation of this approach was 25 pg/mL for THC and 10 pg/mL for THC-COOH in oral fluid. Finally, the method was successfully applied to eight suspected cannabis users. Among them, in six oral fluid samples THC-COOH was determined at a concentration from 13.1 to 47.2 pg/mL.

  18. Effects of Conventional Heating on the Stability of Major Olive Oil Phenolic Compounds by Tandem Mass Spectrometry and Isotope Dilution Assay

    Directory of Open Access Journals (Sweden)

    Giovanni Sindona

    2010-12-01

    Full Text Available The quality of olive oils is sensorially tested by accurate and well established methods. It enables the classification of the pressed oils into the classes of extra virgin oil, virgin oil and lampant oil. Nonetheless, it would be convenient to have analytical methods for screening oils or supporting sensorial analysis using a reliable independent approach based on exploitation of mass spectrometric methodologies. A number of methods have been proposed to evaluate deficiencies of extra virgin olive oils resulting from inappropriate technological treatments, such as high or low temperature deodoration, and home cooking processes. The quality and nutraceutical value of extra virgin olive oil (EVOO can be related to the antioxidant property of its phenolic compounds. Olive oil is a source of at least 30 phenolic compounds, such as oleuropein, oleocanthal, hydroxytyrosol, and tyrosol, all acting as strong antioxidants, radical scavengers and NSAI-like drugs. We now report the efficacy of MRM tandem mass spectrometry, assisted by the isotope dilution assay, in the evaluation of the thermal stability of selected active principles of extra virgin olive oil.

  19. Simplified Method for Quantifying Sulfur Mustard Adducts to Blood Proteins by Ultrahigh Pressure Liquid Chromatography−Isotope Dilution Tandem Mass Spectrometry.

    Science.gov (United States)

    Pantazides, Brooke G; Crow, Brian S; Garton, Joshua W; Quiñones-González, Jennifer A; Blake, Thomas A; Thomas, Jerry D; Johnson, Rudolph C

    2015-02-16

    Sulfur mustard binds to reactive cysteine residues, forming a stable sulfur-hydroxyethylthioethyl [SHETE]adduct that can be used as a long-term biomarker of sulfur mustard exposure in humans. The digestion of sulfur mustard-exposed blood samples with proteinase K following total protein precipitation with acetone produces the tripeptide biomarker [S-HETE]-Cys-Pro-Phe. The adducted tripeptide is purified by solid phase extraction, separated by ultra high pressure liquid chromatography, and detected by isotope dilution tandem mass spectrometry. This approach was thoroughly validated and characterized in our laboratory. The average interday relative standard deviation was ≤ 9.49%, and the range of accuracy was between 96.1 and 109% over a concentration range of 3.00 to 250. ng/mL with a calculated limit of detection of1.74 ng/mL. A full 96-well plate can be processed and analyzed in 8 h, which is 5 times faster than our previous 96-well plate method and only requires 50 μL of serum, plasma, or whole blood. Extensive ruggedness and stability studies and matrix comparisons were conducted to create a robust, easily transferrable method. As a result, a simple and high-throughput method has been developed and validated for the quantitation of sulfur mustard blood protein adducts in low volume blood specimens which should be readily adaptable for quantifying human exposures to other alkylating agents.

  20. A Simplified Method for Quantifying Sulfur Mustard Adducts to Blood Proteins by Ultra-High Pressure Liquid Chromatography-Isotope Dilution Tandem Mass Spectrometry

    Science.gov (United States)

    Pantazides, Brooke G.; Crow, Brian S.; Garton, Joshua W.; Quiñones-González, Jennifer A.; Blake, Thomas A.; Thomas, Jerry D.; Johnson, Rudolph C.

    2016-01-01

    Sulfur mustard binds to reactive cysteine residues, forming a stable sulfur-hydroxyethylthioethyl [S-HETE] adduct that can be used as a long-term biomarker of sulfur mustard exposure in humans. The digestion of sulfur mustard-exposed blood samples with proteinase K following total protein precipitation with acetone produces the tripeptide biomarker [S-HETE]-Cys-Pro-Phe. The adducted tripeptide is purified by solid phase extraction, separated by ultra-high pressure liquid chromatography, and detected by isotope dilution tandem mass spectrometry. This approach was thoroughly validated and characterized in our laboratory. The average interday relative standard deviation was ≤ 9.49%, and the range of accuracy was between 96.1-109% over a concentration range of 3.00 to 250. ng/mL with a calculated limit of detection of 1.74 ng/mL. A full 96-well plate can be processed and analyzed in 8 h which is five times faster than our previous 96-well plate method and only requires 50 µL of serum, plasma, or whole blood. Extensive ruggedness and stability studies and matrix comparisons were conducted to create a robust, easily transferrable method. As a result, a simple and high-throughput method has been developed and validated for the quantitation of sulfur mustard blood protein adducts in low volume blood specimens which should be readily adaptable for quantifying human exposures to other alkylating agents. PMID:25622494

  1. Investigation of mercury-containing proteins by enriched stable isotopic tracer and size-exclusion chromatography hyphenated to inductively coupled plasma-isotope dilution mass spectrometry

    International Nuclear Information System (INIS)

    Shi Junwen; Feng Weiyue; Wang Meng; Zhang Fang; Li Bai; Wang Bing; Zhu Motao; Chai Zhifang

    2007-01-01

    In order to investigate trace mercury-containing proteins in maternal rat and their offspring, a method of enriched stable isotopic tracer ( 196 Hg and 198 Hg) combined with size-exclusion chromatography (SEC) coupled to inductively coupled plasma-isotope dilution mass spectrometry (ICP-IDMS) was developed. Prior to the analysis, 196 Hg- and 198 Hg-enriched methylmercury was administrated to the pregnant rats. Then the mercury-containing proteins in serum and brain cytosol of the dam and pup rats were separated by size-exclusion columns and the mercury was detected by ICP-MS. The ICP-MS spectrogram of the tracing samples showed significantly elevated 196 Hg and 198 Hg isotopic signals compared with the natural ones, indicating that the detection sensitivity could be increased by the tracer method. The contents of mercury in chromatographic fractions of the dam and pup rat brain cytosol were quantitatively estimated by post-column reverse ID-ICP-MS. The quantitative speciation differences of mercury in brain cytosol between the dam and pup rats were observed, indicating that such studies could be useful for toxicological estimation. Additionally, the isotopic ratio measurement of 198 Hg/ 202 Hg in the tracing samples could be used to identify the artifact mercury species caused in the analytical procedure. The study demonstrates that the tracer method combined with high-performance liquid chromatography (HPLC)-ICP-IDMS could provide reliably qualitative and quantitative information on mercury-containing proteins in organisms

  2. Rapid and precise measurement of serum branched-chain and aromatic amino acids by isotope dilution liquid chromatography tandem mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Ruiyue Yang

    Full Text Available BACKGROUND: Serum branched-chain and aromatic amino acids (BCAAs and AAAs have emerged as predictors for the future development of diabetes and may aid in diabetes risk assessment. However, the current methods for the analysis of such amino acids in biological samples are time consuming. METHODS: An isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS method for serum BCAAs and AAAs was developed. The serum was mixed with isotope-labeled BCAA and AAA internal standards and the amino acids were extracted with acetonitrile, followed by analysis using LC/MS/MS. The LC separation was performed on a reversed-phase C18 column, and the MS/MS detection was performed via the positive electronic spray ionization in multiple reaction monitoring mode. RESULTS: Specific analysis of the amino acids was achieved within 2 min. Intra-run and total CVs for the amino acids were less than 2% and 4%, respectively, and the analytical recoveries ranged from 99.6 to 103.6%. CONCLUSION: A rapid and precise method for the measurement of serum BCAAs and AAAs was developed and may serve as a quick tool for screening serum BCAAs and AAAs in studies assessing diabetes risk.

  3. An isotope dilution ultra high performance liquid chromatography-tandem mass spectrometry method for the simultaneous determination of sugars and humectants in tobacco products.

    Science.gov (United States)

    Wang, Liqun; Cardenas, Roberto Bravo; Watson, Clifford

    2017-09-08

    CDC's Division of Laboratory Sciences developed and validated a new method for the simultaneous detection and measurement of 11 sugars, alditols and humectants in tobacco products. The method uses isotope dilution ultra high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) and has demonstrated high sensitivity, selectivity, throughput and accuracy, with recoveries ranging from 90% to 113%, limits of detection ranging from 0.0002 to 0.0045μg/mL and coefficients of variation (CV%) ranging from 1.4 to 14%. Calibration curves for all analytes were linear with linearity R 2 values greater than 0.995. Quantification of tobacco components is necessary to characterize tobacco product components and their potential effects on consumer appeal, smoke chemistry and toxicology, and to potentially help distinguish tobacco product categories. The researchers analyzed a variety of tobacco products (e.g., cigarettes, little cigars, cigarillos) using the new method and documented differences in the abundance of selected analytes among product categories. Specifically, differences were detected in levels of selected sugars found in little cigars and cigarettes, which could help address appeal potential and have utility when product category is unknown, unclear, or miscategorized. Copyright © 2017. Published by Elsevier B.V.

  4. Fast analysis of quaternary ammonium pesticides in food and beverages using cation-exchange chromatography coupled with isotope-dilution high-resolution mass spectrometry.

    Science.gov (United States)

    Nardin, Tiziana; Barnaba, Chiara; Abballe, Franco; Trenti, Gianmaria; Malacarne, Mario; Larcher, Roberto

    2017-10-01

    A fast separation based on cation-exchange liquid chromatography coupled with high-resolution mass spectrometry is proposed for simultaneous determination of chlormequat, difenzoquat, diquat, mepiquat and paraquat in several food and beverage commodities. Solid samples were extracted using a mixture of water/methanol/formic acid (69.6:30:0.4, v/v/v), while liquid samples were ten times diluted with the same solution. Separation was carried out on an experimental length-modified IonPac CS17 column (2 × 15 mm 2 ) that allowed the use of formic acid and acetonitrile as mobile phase. Detection limits for food and beverage matrices were established at 1.5 μg/L for chlormequat, difenzoquat and mepiquat, and 3 μg/L for diquat and paraquat, while for drinking water a pre-analytical sample concentration allowed detection limits of 9 and 20 ng/L, respectively. Precision, as repeatability (RSD%), ranged from 0.2 to 24%, with a median value of 6%, and trueness, as recovery, ranged from 64 to 118%, with a median value of 96%. The method developed was successfully applied to investigate the presence of herbicide residues in commercial commodities (mineral water, orange juice, beer, tea, green coffee bean, toasted coffee powder, cocoa bean, white corn flour, rice and sugar samples). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Effects of conventional heating on the stability of major olive oil phenolic compounds by tandem mass spectrometry and isotope dilution assay.

    Science.gov (United States)

    Attya, Mohamed; Benabdelkamel, Hicham; Perri, Enzo; Russo, Anna; Sindona, Giovanni

    2010-12-01

    The quality of olive oils is sensorially tested by accurate and well established methods. It enables the classification of the pressed oils into the classes of extra virgin oil, virgin oil and lampant oil. Nonetheless, it would be convenient to have analytical methods for screening oils or supporting sensorial analysis using a reliable independent approach based on exploitation of mass spectrometric methodologies. A number of methods have been proposed to evaluate deficiencies of extra virgin olive oils resulting from inappropriate technological treatments, such as high or low temperature deodoration, and home cooking processes. The quality and nutraceutical value of extra virgin olive oil (EVOO) can be related to the antioxidant property of its phenolic compounds. Olive oil is a source of at least 30 phenolic compounds, such as oleuropein, oleocanthal, hydroxytyrosol, and tyrosol, all acting as strong antioxidants, radical scavengers and NSAI-like drugs. We now report the efficacy of MRM tandem mass spectrometry, assisted by the isotope dilution assay, in the evaluation of the thermal stability of selected active principles of extra virgin olive oil.

  6. Determination of nerve agent metabolites in human urine by isotope-dilution gas chromatography-tandem mass spectrometry after solid phase supported derivatization.

    Science.gov (United States)

    Lin, Ying; Chen, Jia; Yan, Long; Guo, Lei; Wu, Bidong; Li, Chunzheng; Feng, Jianlin; Liu, Qin; Xie, Jianwei

    2014-08-01

    A simple and sensitive method has been developed and validated for determining ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA), isobutyl methylphosphonic acid (iBuMPA), and pinacolyl methylphosphonic acid (PMPA) in human urine using gas chromatography-tandem mass spectrometry (GC-MS/MS) coupled with solid phase derivatization (SPD). These four alkyl methylphosphonic acids (AMPAs) are specific hydrolysis products and biomarkers of exposure to classic organophosphorus (OP) nerve agents VX, sarin, RVX, and soman. The AMPAs in urine samples were directly derivatized with pentafluorobenzyl bromide on a solid support and then extracted by liquid-liquid extraction. The analytes were quantified with isotope-dilution by negative chemical ionization (NCI) GC-MS/MS in a selected reaction monitoring (SRM) mode. This method is highly sensitive, with the limits of detection of 0.02 ng/mL for each compound in a 0.2 mL sample of human urine, and an excellent linearity from 0.1 to 50 ng/mL. It is proven to be very suitable for the qualitative and quantitative analyses of degradation markers of OP nerve agents in biomedical samples.

  7. Simultaneous analysis of polychlorinated biphenyls and polychlorinated naphthalenes by isotope dilution comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Dan [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); University of Chinese Academy of Sciences, Beijing 100085 (China); Gao, Lirong, E-mail: gaolr@rcees.ac.cn [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Zheng, Minghui; Wang, Shasha; Liu, Guorui [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

    2016-09-21

    Polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) are listed as persistent organic pollutants (POPs) under the Stockholm Convention. Because they have similar physical and chemical properties, they are coeluted and are usually analyzed separately by different gas chromatography high-resolution mass spectrometry (GC-HRMS) methods. In this study, a novel method was developed for simultaneous analysis of six indicator PCBs, 12 dioxin-like PCBs, and 16 PCNs using isotope dilution comprehensive two-dimensional gas chromatography with high-resolution time-of-flight mass spectrometry (GC × GC-HRTOF-MS). The method parameters, including the type of GC column, oven temperature program, and modulation period, were systematically optimized. Complete separation of all target analytes and the matrix was achieved with a DB-XLB column in the first dimension and a BPX-70 column in the second dimension. The isotope dilution method was used for quantification of the PCBs and PCNs by GC × GC-HRTOF-MS. The method showed good linearity from 5 to 500 pg μL{sup −1} for all the target compounds. The instrumental limit of detection ranged from 0.03 to 0.3 pg μL{sup −1} for the 18 PCB congeners and from 0.09 to 0.6 pg μL{sup −1} for the 16 PCN congeners. Repeatability for triplicate injections was always lower than 20%. The method was successfully applied to the determination of 18 PCBs present at 0.9–2054 pg g{sup −1} and 16 PCNs present at 0.2–15.7 pg g{sup −1} in three species of fish. The GC × GC-HRTOF-MS results agreed with those obtained by GC-HRMS. The GC × GC-HRTOF-MS method proved to be a sensitive and accurate technique for simultaneous analysis of the selected PCBs and PCNs. With the excellent chromatographic separation offered by GC × GC and accurate mass measurements offered by HRTOF-MS, this method allowed identification of non-target contaminants in the fish samples, including organochlorine pesticides and

  8. Differentiation of Boc-protected alpha,delta-/delta,alpha- and beta,delta-/delta,beta-hybrid peptide positional isomers by electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Raju, G; Ramesh, V; Srinivas, R; Sharma, G V M; Shoban Babu, B

    2010-06-01

    Two new series of Boc-N-alpha,delta-/delta,alpha- and beta,delta-/delta,beta-hybrid peptides containing repeats of L-Ala-delta(5)-Caa/delta(5)-Caa-L-Ala and beta(3)-Caa-delta(5)-Caa/delta(5)-Caa-beta(3)-Caa (L-Ala = L-alanine, Caa = C-linked carbo amino acid derived from D-xylose) have been differentiated by both positive and negative ion electrospray ionization (ESI) ion trap tandem mass spectrometry (MS/MS). MS(n) spectra of protonated isomeric peptides produce characteristic fragmentation involving the peptide backbone, the Boc-group, and the side chain. The dipeptide positional isomers are differentiated by the collision-induced dissociation (CID) of the protonated peptides. The loss of 2-methylprop-1-ene is more pronounced for Boc-NH-L-Ala-delta-Caa-OCH(3) (1), whereas it is totally absent for its positional isomer Boc-NH-delta-Caa-L-Ala-OCH(3) (7), instead it shows significant loss of t-butanol. On the other hand, second isomeric pair shows significant loss of t-butanol and loss of acetone for Boc-NH-delta-Caa-beta-Caa-OCH(3) (18), whereas these are insignificant for its positional isomer Boc-NH-beta-Caa-delta-Caa-OCH(3) (13). The tetra- and hexapeptide positional isomers also show significant differences in MS(2) and MS(3) CID spectra. It is observed that 'b' ions are abundant when oxazolone structures are formed through five-membered cyclic transition state and cyclization process for larger 'b' ions led to its insignificant abundance. However, b(1)(+) ion is formed in case of delta,alpha-dipeptide that may have a six-membered substituted piperidone ion structure. Furthermore, ESI negative ion MS/MS has also been found to be useful for differentiating these isomeric peptide acids. Thus, the results of MS/MS of pairs of di-, tetra-, and hexapeptide positional isomers provide peptide sequencing information and distinguish the positional isomers. Copyright 2010 John Wiley & Sons, Ltd.

  9. Chemical analysis of radioactive mixed liquid wastes by Alpha/Gamma Spectrometry, ICP-OES and Arsenazo III

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Eduardo G.A.; Ferreira, Rafael V.P.; Araujo, Leandro G.; Dellamano, Jose Claudio; Marumo, Julio T., E-mail: jtmarumo@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Taddei, Maria Helena Tirollo, E-mail: mhtaddei@cnen.gov.br [Comissao Nacional de Energia Nuclear (LAPOC/CNEN), Pocos de Caldas, MG (Brazil). Laboratorio de Pocos de Caldas

    2013-07-01

    Radioactive waste characterization is a very important step in radioactive waste management because it can influence subsequent stages, as waste conditioning, storage and disposal. This characterization must provide reliable information in order to satisfy some quality requirements based on chemical analysis of representative waste samples. This paper presents procedures adopted for characterization of thirteen different mixed liquid wastes stored at Waste Management Laboratory of Nuclear and Energy Research Institute, IPEN-CNEN/SP. The first action was the sampling of representative samples of each liquid storage package, followed by the alpha and gamma spectrometry, Arsenazo III and ICP-OES analysis. It was identified the radionuclides U, Pu, Cs and Am and others seven chemical elements. The results obtained will be used to perform the treatment of these wastes. (author)

  10. Determination of C and O and other elements by alpha-induced X-ray energy spectrometry

    International Nuclear Information System (INIS)

    Henningsen, W.P.; Schaetzler, H.P.; Kuehn, W.

    1978-01-01

    X-ray energy spectrometry combined with alpha-excitation by means of radionuclides, especially Po-210, has been found as a versatile tool for multielement analysis. Down to Z = 6 (carbon) qualitative and quantitative measurements have been carried out with energy resolution good enough to separate adjacent elements. Thereby errors and lowest detectable concentrations were in the region of one percent. By utilizing M- and L-X-radiation the set of detectable elements can be opened to high atomic numbers. As an example with special regard to environmental research cadmium in organic matrix was measured down to 100 ppm without any preconcentration. Much lower detection limits might be reached by appropriate measures. (orig.) [de

  11. Determination of As and Se in crude oil diluted in xylene by inductively coupled plasma mass spectrometry using a dynamic reaction cell for interference correction on 80Se

    International Nuclear Information System (INIS)

    Albuquerque, Fernanda Inda de; Duyck, Christiane B.; Fonseca, Teresa Cristina O.; Saint'Pierre, Tatiana D.

    2012-01-01

    Arsenic and selenium can be found in crude oils and represent an important source of pollution when released to the environment during any stage of extraction or refinery. These elements present low sensitivity in the direct determination by inductively coupled plasma mass spectrometry (ICP-MS), due to their high ionization potential, and are also prone to spectral interferences. Hydride generation (HG) can be alternatively employed for the separation of these analytes from the sample matrix and introduction into the instrument. However, the required sample preparation usually increases the analysis time. In this work, a method was developed for the determination of As and Se in crude oil by ICP-MS, after sample dilution in xylene. The use of a dynamic reaction cell (DRC) allowed for the overcoming of Ar 2 + interference on 80 Se, but was not necessary for As, since interference on m/z 75 was not observed. The optimized operational conditions for 75 As and 80 Se were: 1350 W of RF power, 0.4 L min −1 of Ar nebulizer and 0.7 L min −1 of Ar auxiliary flow rates. The DRC conditions for 80 Se were 0.5 L min −1 of methane and rejection parameter q (Rpq) of 0.2. The analyses were carried out by analyte addition and the limits of detection (LOD) were 0.04 μg kg −1 for As and 0.1 μg kg −1 for Se. The accuracy was verified by the analysis of residual fuel oil certified material, with agreement at a 95% confidence level. Nine Brazilian crude oil samples were analyzed and the results compared to those obtained by hydride generation ICP-MS. In this case, samples were decomposed with nitric acid in a digester block, the analytes pre-reduced with HCl 6 mol L −1 and the determination carried out by external calibration. Although better instrumental LODs were obtained by HG (0.002 μg kg −1 of As and 0.04 μg kg −1 of Se), the direct determination of As and Se in crude oil diluted in xylene by DRC-ICP-MS showed to be an adequate and a faster method. - Highlights

  12. Determination of mycotoxins in milk-based products and infant formula using stable isotope dilution assay and liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Zhang, Kai; Wong, Jon W; Hayward, Douglas G; Vaclavikova, Marta; Liao, Chia-Ding; Trucksess, Mary W

    2013-07-03

    A stable isotope dilution assay and liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of 12 mycotoxins, aflatoxins B₁, B₂, G₁, G₂, and M₁, deoxynivalenol, fumonisins B₁, B₂, and B₃, ochratoxin A, T-2 toxin, and zearalenone, in milk-based infant formula and foods. Samples were fortified with 12 ¹³C uniformly labeled mycotoxins ([¹³C]-mycotoxins) that correspond to the 12 target mycotoxins and prepared by dilution and filtration, followed by LC-MS/MS analysis. Quantitation was achieved using the relative response factors of [¹³C]-mycotoxins and target mycotoxins. The average recoveries in fortified milk, milk-based infant formula, milk powder, and baby yogurt of aflatoxins B₁, B₂, G₁, and G₂ (2, 10, and 50 μg/kg), aflatoxin M₁ (0.5, 2.5, and 12.5 μg/kg), deoxynivalenol, fumonisins B₁, B₂, and B₃ (40, 200, and 1000 μg/kg), ochratoxin A, T-2 toxin, and zearalenone (20, 100, and 500 μg/kg), range from 89 to 126% with RSDs of milk-based infant formula) to 136% (T-2 toxin, 20 μg/kg, milk powder), with RSDs ranging from 2 to 25%. The limits of quantitation (LOQs) were from 0.01 μg/kg (aflatoxin M₁) to 2 (fumonisin B₁) μg/kg. Aflatoxin M₁ was detected in two European Reference materials at 0.127 ± 0.013 μg/kg (certified value = 0.111 ± 0.018 μg/kg) and 0.46 ± 0.04 μg/kg (certified value = 0.44 ± 0.06 μg/kg), respectively. In 60 local market samples, aflatoxins B₁ (1.14 ± 0.10 μg/kg) and B₂ (0.20 ± 0.03 μg/kg) were detected in one milk powder sample. Aflatoxin M₁ was detected in three imported samples (condensed milk, milk-based infant formula, and table cream), ranging from 0.10 to 0.40 μg/kg. The validated method provides sufficient selectivity, sensitivity, accuracy, and reproducibility to screen for aflatoxin M₁ at nanograms per kilogram concentrations and other mycotoxins, without using standard addition or matrix-matched calibration

  13. Reduction of measurement uncertainty by experimental design in high-order (double, triple, and quadruple) isotope dilution mass spectrometry: application to GC-MS measurement of bromide.

    Science.gov (United States)

    Pagliano, Enea; Mester, Zoltán; Meija, Juris

    2013-03-01

    Since its introduction a century ago, isotope dilution analysis has played a central role in developments of analytical chemistry. This method has witnessed many elaborations and developments over the years. To date, we have single, double, and even triple isotope dilution methods. In this manuscript, we summarize the conceptual aspects of isotope dilution methods and introduce the quadruple dilution and the concept of exact matching triple and quadruple dilutions. The comparison of isotope dilution methods is performed by determination of bromide ions in groundwater using novel ethyl-derivatization chemistry in conjunction with GC/MS. We show that the benefits of higher-order isotope dilution methods are countered with a greater need for careful experimental design of the isotopic blends. Just as for ID(2)MS, ID(3)MS and ID(4)MS perform best when the isotope ratio of one sample/spike blend is matched with that of a standard/spike blend (exact matching).

  14. Measurement of airborne concentrations of radon-220 daughter products by alpha-particle spectrometry

    International Nuclear Information System (INIS)

    Kerr, G.D.; Ryan, M.T.; Perdue, P.T.

    1978-01-01

    The decay of naturally occurring uranium-238 and thorium-232 produces radon-222 and radon-220 isotopes which can escape into the atmosphere. If these radon gases become concentrated in air, their daughter products may present an inhalation hazard to man. The airborne concentrations of radon-222 can usually be measured very accurately in the presence of normal airborne concentrations of radon-220 and its daughters. In contrast, the measurements of the airborne concentrations of radon-220 daughters are usually complicated by the presence of radon-222 and its daughters even at normally occurring airborne concentrations. The complications involved in these measurements can be overcome in most situations by using an alpha particle spectrometer to distinguish the activity of radon-222 daughters from that due to radon-220 daughters collected on a filter. A practical spectrometer for field measurements of alpha particle activity on a filter is discussed

  15. Alpha-ray spectrometry at high temperature by using a compound semiconductor detector.

    Science.gov (United States)

    Ha, Jang Ho; Kim, Han Soo

    2013-11-01

    The use of conventional radiation detectors in harsh environments is limited by radiation damage to detector materials and by temperature constraints. We fabricated a wide-band gap semiconductor radiation detector based on silicon carbide. All the detector components were considered for an application in a high temperature environment like a nuclear reactor core. The radiation response, especially to alpha particles, was measured using an (241)Am source at variable operating voltages at room temperature in the air. The temperature on detector was controlled from 30°C to 250°C. The alpha-particle spectra were measured at zero bias operation. Even though the detector is operated at high temperature, the energy resolution as a function of temperature is almost constant within 3.5% deviation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. An experimental study of symmetric and asymmetric peak-fitting parameters for alpha-particle spectrometry

    International Nuclear Information System (INIS)

    Martin Sanchez, A.; Vera Tome, F.; Caceres Marzal, D.; Bland, C.J.

    1994-01-01

    A pulse-height spectrum of alpha-particle emissions at discrete energies can be fitted by the peak-shape functions generated by combining asymmetric truncated exponential functions with a symmetric Gaussian distribution. These functions have been applied successfully by several workers. A correlation was previously found between the variance of the symmetric Gaussian portion of the fitting function, and the parameter characterising the principal exponential tailing function. The results of a more detailed experimental study are reported, which involve varying the angle and the distance between the source and the detector. This analysis shows that the parameters of the symmetric and asymmetric parts of the fitted functions seem to depend on either the detector or the source. These parameters are influenced by the energy loss suffered by the alpha-particles as well as by the efficiency of charge collection in the solid-state detector. (orig.)

  17. Application of alpha spectrometry to the discovery of new elements by heavy-ion-beam bombardment

    International Nuclear Information System (INIS)

    Nitschke, J.M.

    1983-05-01

    Starting with polonium in 1898, α-spectrometry has played a decisive role in the discovery of new, heavy elements. For even-even nuclei, α-spectra have proved simple to interpret and exhibit systematic trends that allow extrapolation to unknown isotopes. The early discovery of the natural α-decay series led to the very powerful method of genetically linking the decay of new elements to the well-established α-emission of daughter and granddaughter nuclei. This technique has been used for all recent discoveries of new elements including Z = 109. Up to mendelevium (Z = 101), thin samples suitable for α-spectrometry were prepared by chemical methods. With the advent of heavy-ion accelerators new sample preparation methods emerged. These were based on the large momentum transfer associated with heavy-ion reactions, which produced energetic target recoils that, when ejected from the target, could be thermalized in He gas. Subsequent electrical deposition or a He-jet technique yielded samples that were not only thin enough for α-spectroscopy, but also for α- and #betta#-recoil experiments. Many variations of these methods have been developed and are discussed. For the synthesis of element 106 an aerosol-based recoil transport technique was devised. In the most recent experiments, α-spectrometry has been coupled with the magnetic analysis of the recoils. The time from production to analysis of an isotope has thereby been reduced to 10 - 6 s; while it was 10 - 1 to 10 0 s for He-jets and 10 1 to 10 3 s for rapid chemical separations. Experiments are now in progress to synthesize super heavy elements (SHE) and to analyze them with these latest techniques. Again, α-spectrometry will play a major role since the expected signature for the decay of a SHE is a sequence of α-decays followed by spontaneous fission

  18. Thorium: one of the analytical techniques in neutronic activation and alpha spectrometry of the CDTN (Brazilian Nuclear Technology Development Center) in the last three decades

    International Nuclear Information System (INIS)

    Menezes, M.A.B.C.; Sabino, C.V.S.

    1994-01-01

    For long years, the CDTN (Brazilian Nuclear Technology Development Center ) has applied several analytical techniques in the thorium determination. This work is about the evolution of the neutronic activation in the thorium 232 analysis from the 1960's to now. The importance of the analysis request and alpha spectrometry for the thorium 228 and thorium 232 determination is emphasized. (J.A.M.M.)

  19. Application of the reference method isotope dilution gas chromatography mass spectrometry (ID/GC/MS) to establish metrological traceability for calibration and control of blood glucose test systems.

    Science.gov (United States)

    Andreis, Elisabeth; Küllmer, Kai; Appel, Matthias

    2014-05-01

    Self-monitoring of blood glucose (BG) by means of handheld BG systems is a cornerstone in diabetes therapy. The aim of this article is to describe a procedure with proven traceability for calibration and evaluation of BG systems to guarantee reliable BG measurements. Isotope dilution gas chromatography mass spectrometry (ID/GC/MS) is a method that fulfills all requirements to be used in a higher-order reference measurement procedure. However, this method is not applicable for routine measurements because of the time-consuming sample preparation. A hexokinase method with perchloric acid (PCA) sample pretreatment is used in a measurement procedure for such purposes. This method is directly linked to the ID/GC/MS method by calibration with a glucose solution that has an ID/GC/MS-determined target value. BG systems are calibrated with whole blood samples. The glucose levels in such samples are analyzed by this ID/GC/MS-linked hexokinase method to establish traceability to higher-order reference material. For method comparison, the glucose concentrations in 577 whole blood samples were measured using the PCA-hexokinase method and the ID/GC/MS method; this resulted in a mean deviation of 0.1%. The mean deviation between BG levels measured in >500 valid whole blood samples with BG systems and the ID/GC/MS was 1.1%. BG systems allow a reliable glucose measurement if a true reference measurement procedure, with a noninterrupted traceability chain using ID/GC/MS linked hexokinase method for calibration of BG systems, is implemented. Systems should be calibrated by means of a traceable and defined measurement procedure to avoid bias. © 2014 Diabetes Technology Society.

  20. Determination of the maleic acid in rat urine and serum samples by isotope dilution-liquid chromatography-tandem mass spectrometry with on-line solid phase extraction.

    Science.gov (United States)

    Chen, Hsin-Chang; Wu, Charlene; Wu, Kuen-Yuh

    2015-05-01

    A rapid and simple on-line solid-phase extraction coupled with isotope dilution-liquid chromatography-tandem mass spectrometry (SPE-ID-LC-MS/MS) method was developed to quantitate maleic acid in serum and urine of SpragueDawley (SD) rats. The aforementioned biological samples were spiked with (13)C2-maleic acid, vigorously vortexed, added with acetonitrile to precipitate proteins, and then injected into the on-line SPE-LC-MS/MS system for quantification. Upon validation, this method demonstrated excellent feasibility and sensitivity: calibration curves for maleic acid in serum and urine display excellent linearity with the coefficient of determination (R(2)) greater than 0.999; the limits of detection and quantitation (LOD and LOQ) for maleic acid were determined at 0.2 and 0.5μg L(-1), respectively. Additionally, intra-day accuracy for maleic acid in serum and urine samples ranged from 94.0% to 100.2% and 101.3% to 104.4%, respectively. Furthermore, inter-day accuracy ranged from 93.6% to 101.0% and from 102.3% to 111.4% in serum and urine samples, respectively. Intra-day precision %RSD of maleic acid in serum and urine samples was 13.8% or less, whereas the inter-day precision was 6.1% or less. The matrix effects were not found to be statistically significant (p=0.9145 and p=0.5378, correspondingly) based on the calculations of recovery functions. The collected serum and urine samples were analyzed using SPE-ID-LC-MS/MS. Our results reveal trace levels of maleic acid in the control rats, demonstrating that this method is capable of analyzing background levels of contaminants in biofluids with excellent sensitivity and specificity at part-per-billion levels concentrations in complex matrices. Copyright © 2015. Published by Elsevier B.V.

  1. Lewisite Metabolites in Urine by Solid Phase Extraction-Dual Column Reversed-Phase Liquid Chromatography-Isotope Dilution Tandem Mass Spectrometry.

    Science.gov (United States)

    Palcic, Jason D; Donovan, Stephen F; Jones, Janet S; Flagg, E Lindsay; Salonga, Redentor A; Mock, Walter E; Asirvatham, Victor S

    2016-07-01

    Lewisite (2-chlorovinyldichloroarsine) is a chemical warfare agent developed during World War I. A quantitative method using solid phase extraction (SPE) followed by dual column liquid chromatography (LC)-isotope dilution tandem mass spectrometry (MS-MS) was developed for the determination of (2-chlorovinyl)arsonic acid (CVAOA), a metabolite of Lewisite, in human urine. The sample was treated with hydrogen peroxide to oxidize any (2-chlorovinyl)arsonous acid (CVAA) that remained in the trivalent arsenic oxidation state. There was 1.19% (arsenic purity) of bis-(2-chlorovinyl)arsinic acid (BCVAOA), a minor Lewisite metabolite, in the stock CVAA material. The high-throughput method qualitatively assessed BCVAOA simultaneously utilizing normal-phase silica SPE followed by reversed-phase C18 LC for an orthogonal separation. The chromatographic method results in a 5.8-min cycle time with adequate retention (k' = 2.4) of CVAOA. The mass spectrometer was operated in positive electrospray ionization mode with quantitative m/z 186.9→61.0 and confirmation 186.9→91.0 mass transitions. This selective method demonstrated linearity, accuracy and reproducibility for the clinically relevant calibration range (25-3,200 µg/L as CVAA). The method detection limit was 3.3 µg/L as CVAA from a 10 µL injection. This LC-MS-MS emergency response method has a throughput of >240 samples (2.5 extracted 96-well plates) per day. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Studies on the analysis of 25-hydroxyvitamin D3 by isotope-dilution liquid chromatography–tandem mass spectrometry using enzyme-assisted derivatisation

    International Nuclear Information System (INIS)

    Abdel-Khalik, Jonas; Crick, Peter J.; Carter, Graham D.; Makin, Hugh L.; Wang, Yuqin; Griffiths, William J.

    2014-01-01

    Highlights: • New method for the analysis of 25-hydroxyvitamin D 3 exploiting Girard P derivatisation. • Method also applicable to vitamin D 3 , 1α,25- and 24,25-dihydroxyvitamin D 3 . • By modification of the method 3-epi-25-hydroxyvitamin D 3 can also be analysed. - Abstract: The total serum concentration of 25-hydroxyvitamins D (25-hydroxyvitamin D 3 and 25-hydroxyvitamin D 2 ) is currently used as an indicator of vitamins D status. Vitamins D insufficiency is claimed to be associated with multiple diseases, thus accurate and precise reference methods for the quantification of 25-hydroxyvitamins D are needed. Here we present a novel enzyme-assisted derivatisation method for the analysis of vitamins D metabolites in adult serum utilising 25-[26,26,26,27,27,27- 2 H 6 ]hydroxyvitamin D 3 as the internal standard. Extraction of 25-hydroxyvitamins D from serum is performed with acetonitrile, which is shown to be more efficient than ethanol. Cholesterol oxidase is used to oxidize the 3β-hydroxy group in the vitamins D metabolites followed by derivatisation of the newly formed 3-oxo group with Girard P reagent. 17β-Hydroxysteroid dehydrogenase type 10 is shown to oxidize selectively the 3α-hydroxy group in the 3α-hydroxy epimer of 25-hydroxyvitamin D 3 . Quantification is achieved by isotope-dilution liquid chromatography–tandem mass spectrometry. Recovery experiments for 25-hydroxyvitamin D 3 performed on adult human serum give recovery of 102–106%. Furthermore in addition to 25-hydroxyvitamin D 3 , 24,25-dihydroxyvitamin D 3 and other uncharacterised dihydroxy metabolites, were detected in adult human serum

  3. Studies on the analysis of 25-hydroxyvitamin D{sub 3} by isotope-dilution liquid chromatography–tandem mass spectrometry using enzyme-assisted derivatisation

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Khalik, Jonas, E-mail: J.A.F.A.ABDEL-KHALIK.744116@swansea.ac.uk [Institute of Mass Spectrometry, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Crick, Peter J. [Institute of Mass Spectrometry, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Carter, Graham D. [DEQAS, Imperial College Healthcare NHS Trust, Clinical Biochemistry Department, Charing Cross Hospital, Fulham Palace Rd, London W6 8RF (United Kingdom); Makin, Hugh L. [Barts and the Royal London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AD (United Kingdom); Wang, Yuqin [Institute of Mass Spectrometry, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Griffiths, William J., E-mail: w.j.griffiths@swansea.ac.uk [Institute of Mass Spectrometry, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom)

    2014-04-11

    Highlights: • New method for the analysis of 25-hydroxyvitamin D{sub 3} exploiting Girard P derivatisation. • Method also applicable to vitamin D{sub 3}, 1α,25- and 24,25-dihydroxyvitamin D{sub 3}. • By modification of the method 3-epi-25-hydroxyvitamin D{sub 3} can also be analysed. - Abstract: The total serum concentration of 25-hydroxyvitamins D (25-hydroxyvitamin D{sub 3} and 25-hydroxyvitamin D{sub 2}) is currently used as an indicator of vitamins D status. Vitamins D insufficiency is claimed to be associated with multiple diseases, thus accurate and precise reference methods for the quantification of 25-hydroxyvitamins D are needed. Here we present a novel enzyme-assisted derivatisation method for the analysis of vitamins D metabolites in adult serum utilising 25-[26,26,26,27,27,27-{sup 2}H{sub 6}]hydroxyvitamin D{sub 3} as the internal standard. Extraction of 25-hydroxyvitamins D from serum is performed with acetonitrile, which is shown to be more efficient than ethanol. Cholesterol oxidase is used to oxidize the 3β-hydroxy group in the vitamins D metabolites followed by derivatisation of the newly formed 3-oxo group with Girard P reagent. 17β-Hydroxysteroid dehydrogenase type 10 is shown to oxidize selectively the 3α-hydroxy group in the 3α-hydroxy epimer of 25-hydroxyvitamin D{sub 3}. Quantification is achieved by isotope-dilution liquid chromatography–tandem mass spectrometry. Recovery experiments for 25-hydroxyvitamin D{sub 3} performed on adult human serum give recovery of 102–106%. Furthermore in addition to 25-hydroxyvitamin D{sub 3}, 24,25-dihydroxyvitamin D{sub 3} and other uncharacterised dihydroxy metabolites, were detected in adult human serum.

  4. Investigation of mercury-containing proteins by enriched stable isotopic tracer and size-exclusion chromatography hyphenated to inductively coupled plasma-isotope dilution mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Shi Junwen [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)]|[Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Feng Weiyue [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)]. E-mail: fengwy@mail.ihep.ac.cn; Wang Meng [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)]|[Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Zhang Fang [Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Li Bai [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Wang Bing; Zhu Motao [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)]|[Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Chai Zhifang [Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)]|[Institute of Nuclear Technology, Shenzhen University, Shenzhen 518060 (China)]|[Institute of Nanochemistry and Nanosafety, Shanghai University, Shanghai (China)

    2007-01-30

    In order to investigate trace mercury-containing proteins in maternal rat and their offspring, a method of enriched stable isotopic tracer ({sup 196}Hg and {sup 198}Hg) combined with size-exclusion chromatography (SEC) coupled to inductively coupled plasma-isotope dilution mass spectrometry (ICP-IDMS) was developed. Prior to the analysis, {sup 196}Hg- and {sup 198}Hg-enriched methylmercury was administrated to the pregnant rats. Then the mercury-containing proteins in serum and brain cytosol of the dam and pup rats were separated by size-exclusion columns and the mercury was detected by ICP-MS. The ICP-MS spectrogram of the tracing samples showed significantly elevated {sup 196}Hg and {sup 198}Hg isotopic signals compared with the natural ones, indicating that the detection sensitivity could be increased by the tracer method. The contents of mercury in chromatographic fractions of the dam and pup rat brain cytosol were quantitatively estimated by post-column reverse ID-ICP-MS. The quantitative speciation differences of mercury in brain cytosol between the dam and pup rats were observed, indicating that such studies could be useful for toxicological estimation. Additionally, the isotopic ratio measurement of {sup 198}Hg/{sup 202}Hg in the tracing samples could be used to identify the artifact mercury species caused in the analytical procedure. The study demonstrates that the tracer method combined with high-performance liquid chromatography (HPLC)-ICP-IDMS could provide reliably qualitative and quantitative information on mercury-containing proteins in organisms.

  5. Substoichiometric isotope dilution mass spectrometry of boron by the ion-pair extraction with halogenated salicyl alcohol derivatives and a quaternary ammonium salt.

    Science.gov (United States)

    Morita, Keisuke; Imura, Hisanori

    2012-01-01

    Novel salicyl alcohol derivatives (H(2)X(n)sal), 5-bromo-, 3,5-dibromo-, and 3,5-diiodosalicyl alcohol which were abbreviated to H(2)Brsal, H(2)Br(2)sal, and H(2)I(2)sal, respectively, were synthesized and used for the selective extraction of boric acid. Boric acid was extracted with each H(2)X(n)sal into chlorobenzene containing trioctylmethylammonium chloride (TOMACl) as an ion-pair complex, TOMA·B(X(n)sal)(2), at a different pH range. The extraction constant (K(ex)) of boric acid was determined by the equilibrium analyses including the formation of hydrogen-bonded complex of each H(2)X(n)sal with TOMACl in the organic phase. The K(ex) values obtained by salicyl alcohol (H(2)sal) and its derivatives were decreased in the order of H(2)I(2)sal ≥ H(2)Br(2)sal > H(2)Brsal > H(2)sal. The most powerful extractant, H(2)I(2)sal, was employed for the substoichiometric extraction of boric acid, which was extracted at pH 5 - 9 with a substoichiometric amount of TOMACl in the presence of an excess of H(2)I(2)sal. The present substoichiometric separation method combined with the stable isotope dilution analysis using inductively coupled plasma mass spectrometry (ICP-MS) could be successfully applied to the determination of boron in a reference material of high-analysis compound fertilizer (FAMIC-A-08) without any correction as to the isotopic abundance.

  6. Quantitative analysis of penicillins in porcine tissues, milk and animal feed using derivatisation with piperidine and stable isotope dilution liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    van Holthoon, Frédérique; Mulder, Patrick P J; van Bennekom, Eric O; Heskamp, Henri; Zuidema, Tina; van Rhijn, Hans J A

    2010-04-01

    Penicillins are used universally in both human and veterinary medicine. The European Union (EU) has established maximum residue levels (MRLs) for most ss-lactam antibiotics in milk and animal tissues and included them in the National Residue Monitoring Programs. In this study, a novel method is described for the determination and confirmation of eight penicillins in porcine tissues, milk and animal feed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). To prevent degradation of penicillin residues during workup, a derivatisation procedure was developed, by which penicillins were converted to stable piperidine derivatives. Deuterated piperidine derivatives were synthesised for all relevant penicillins, enabling the use of isotope dilution for accurate quantification. Penicillin residues were derivatised in the crude extract with piperidine and isolated using solid-phase extraction. The penicillin piperidine derivatives were determined by LC-MS/MS. The method was validated at the current MRLs, which range from 25-300 microg kg(-1) in muscle and kidney to 4-30 microg kg(-1) in milk as well as at the target value of 100 microg kg(-1) chosen for animal feed, according to the EU requirements for a quantitative confirmatory method. Accuracy ranged from 94-113% (muscle), 83-111% (kidney) and 87-103% (milk) to 88-116% (animal feed). Intra-day precision (relative standard deviation (RSD)(r)) ranged from 5-13% (muscle, n = 18), 4-17% (kidney, n = 7) and 5-18% (milk, n = 7) to 11-32% (animal feed, n = 18). Inter-day precision (RSD(RL), n = 18) ranged from 6-23% (muscle) to 11-36% (animal feed). From the results, it was concluded that the method was fit for purpose at the target MRLs in animal tissue and target levels for animal feed.

  7. Determination of urinary cortisol, cortisone and 6-sulfatoxymelatonin using dilute and shoot ultra-high pressure liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Sniecinska-Cooper, Anna Maria; Shah, Ajit Jesang; Dimitriou, Dagmara; Iles, Ray Kruse; Butler, Stephen Andrew; Bayford, Richard

    2015-01-26

    Human sleep is a natural part of every individual's life. Clear relationship between sleep and endocrine system has been already established. In particular, melatonin and cortisol are known to affect and regulate sleep/wake patterns. Here we report the development of an ultra-high pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous measurement of 6-sulfatoxymelatonin (MT6s), cortisol and cortisone in urine. A separate method was developed for measurement of creatinine in urine. These levels were used to normalise the levels of analytes. First void morning urine samples were collected from 24 healthy volunteers. Samples were diluted 1:1 in water prior to injection onto reversed-phase C18 column and analysed using UHPLC-MS/MS method. Linear calibrations were obtained for all analytes with correlation coefficient in the range 0.998-0.999. The observed concentration was found to be in the range 92-105% for cortisol, 92-107% for cortisone and between 93 and 120% for MT6s of the reference levels. The total run time of 6 min with all peaks of interest eluting within 3 min was obtained. This demonstrates the feasibility of utilising the method for large multi-scale studies, where high throughput is required for studying the circadian rhythm of melatonin and cortisol secretion. These hormones play significant role in circadian rhythm and sleep/wake cycle; therefore it is important to monitor the levels of these endocrine markers in individuals suffering from sleep disorders. It is also beneficial with clinical applications to analyse melatonin and cortisol simultaneously in order to assess their interrelationships of these substances, such as their effect on diurnal rhythm and sleep. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Separation of Ra and Th from rock matrices for alpha-spectrometry

    International Nuclear Information System (INIS)

    Ditchburn, R.G.; Whitehead, N.E.

    1995-01-01

    Dating rocks using 226 Ra/ 230 Th isochrons demands radiochemical purification of radium and thorium. This paper presents an improved method. Rocks are solubilised by nitric/hydrofluoric digestion followed by dissolution of insoluble fluorides by boric/nitric acids, and Th is extracted by passing the 8M nitric solution through an anion column in nitrate form. The eluant contains Ra and Ba which are precipitated as sulphate and redissolved in alkaline EDTA. Complete separation of Ba and Ra from sulphate is on an AG 1 x 8 anion column in EDTA form, which was found better than the chloride form. The Ba+Ra is separated on an AG 50W x 8 cation column, and uses CDTA as an eluant for Ba. Careful pH control is essential. Ra elutes later with EDTA or 4M HCl and is precipitated with 125μg barium as sulphate to yield a source suitable for α-spectrometry, or further treated to electroplate the Ra. The yield tracers used are 228 Th and 224 Ra. Because the sample contains natural 224 Ra a correction must be applied, calculated from the amount of natural 232 Th in the Th spectrum. Th may be precipitated with 100 μg of ferric iron and gives a spectrometry-quality source, but further purification and electrodeposition was found to be preferable. Variations on the method for the case of analysis of calcium-rich fish otoliths are described. (author) 37 refs.; 3 figs

  9. A rapid method of extraction of uranium and thorium from granite for alpha spectrometry

    International Nuclear Information System (INIS)

    Gascoyne, M.; Larocque, J.P.A.

    1984-01-01

    The lithium metaborate fusion technique for analysis of rock samples has been adapted for the alpha spectrometric determination of uranium and thorium isotope abundances in granite. Powdered granite is spiked with a solution of a uranium-thorium isotope tracer, mixed with LiBO 2 in a 1: 3 ratio and fused at 950 o C in a graphite crucible. The mixture is poured into 1 M HNO 3 and stirred until dissolved. Uranium and thorium are simultaneously extracted with 10% tributylphosphate(TBP) in amyl acetate using AI(NO 3 ) 3 as the salting agent, and then back-extracted into 1 M H 2 SO 4 . Uranium is separated from thorium using anion exchange resin and, after further purification, each is plated onto steel discs for alpha counting. Overall chemical yields are adequate at present (generally 20 to 60%). Preliminary tests show the TBP extraction step to be almost quantitative for both elements, in spite of the presence of silicon and high concentrations of aluminium. This procedure is much faster than the usual acid digestion technique, and uranium and thorium discs for counting can be prepared in approximately eight hours, starting from rock powder. (author)

  10. A rapid method of extraction of uranium and thorium from granite for alpha spectrometry

    International Nuclear Information System (INIS)

    Gascoyne, M.; Larocque, J.P.A.

    1984-01-01

    The lithium metaborate fusion technique for analysis of rock samples has been adapted for the alpha spectrometric determination of uranium and thorium isotope abundances in granite. Powdered granite is spiked with a solution of a uranium-thorium isotope tracer, mixed with LiBO 2 in a 1:3 ratio and fused at 950 0 C in a graphite crucible. The mixture is poured into 1 M HNO 3 and stirred until dissolved. Uranium and thorium are simultaneously extracted with 10% tributylphosphate (TBP) in amyl acetate using Al(NO 3 ) 3 as the salting agent, and then back-extracted into 1 M H 2 SO 4 . Uranium is separated from thorium using anion exchange resin and, after further purification, each is plated onto steel discs for alpha counting. Overall chemical yields are adequate at present (generally 20 to 60%). Preliminary tests show the TBP extraction step to be almost quantitative for both elements, in spite of the presence of silicon and high concentrations of aluminium. This procedure is much faster than the usual digestion technique, and uranium and thorium discs for counting can be prepared in approximately eight hours, starting from rock powder. (orig.)

  11. A rapid method of extraction of uranium and thorium from granite for alpha spectrometry

    Science.gov (United States)

    Gascoyne, M.; Larocque, J. P. A.

    1984-06-01

    The lithium metaborate fusion technique for analysis of rock samples has been adapted for the alpha spectrometric determination of uranium and thorium isotope abundances in granite. Powdered granite is spiked with a solution of a uranium-thorium isotope tracer, mixed with LiBO 2 in a 1:3 ratio and fused at 950°C in a graphite crucible. The mixture is poured into 1 M HNO 3 and stirred until dissolved. Uranium and thorium are simultaneously extracted with 10% tributylphosphate (TBP) in amyl acetate using Al(NO 3) 3 as the salting agent, and then back-extracted into 1 M H 2SO 4. Uranium is separated from thorium using anion exchange resin and, after further purification, each is plated onto steel discs for alpha counting. Overall chemical yields are adequate at present (generally 20 to 60%). Preliminary tests show the TBP extraction step to be almost quantitative for both elements, in spite of the presence of silicon and high concentrations of aluminium. This procedure is much faster than the usual acid digestion technique, and uranium and thorium discs for counting can be prepared in approximately eight hours, starting from rock powder.

  12. Contribution to the study of the geophysical behaviour of lead-210 by application of alpha spectrometry; Contribution a l'etude du comportement geophysique du plomb 210 par application de la spectrometrie alpha

    Energy Technology Data Exchange (ETDEWEB)

    Nezami, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-06-01

    A study of the changes in the lead-210 contents of rain-water and of water produced by melting polar ice has required the development of a method for dosing lead-210, an {alpha} emitter. This method is 40 times more sensitive than that which measures the lead-210 by bismuth-210, a ({beta} emitter. The first part of the report presents the study of a spectrometry using semiconductor detectors; a catalogue of a spectra shows the advantages of this method. In the second part will be found at first a new chemical separation method for polonium-210 and the results obtained with this method. The main results obtained on the geophysical behaviour of lead-210 are the following: - the monthly lead-210 and polonium-210 contents in rain water are approximately constant with time. - in the Gif-sur-Yvette region, the clean-up by 'dry fall-out' can attain 40 to 50 per cent of the total fall-out. - a study of Antarctic ice samples makes it possible to determine an annual accumulation rate equivalent to 13.8 cm of water and to show discrepancies in the periodic concentrations which correspond to the latest maxima of solar activity. - a balance is drawn up between the radon produced by the continents and the lead-210 fall-out. (author) [French] Une etude sur les variations de la teneur en plomb 210 des eaux de pluie et des eaux de fusion des glaces polaires a necessite la mise au point d'une methode de dosage du plomb 210 emetteur {alpha}. Cette methode permet d'obtenir une sensibilite quarante fois superieure a celle dosant le plomb 210 par le bismuth 210 emetteur {beta}. La premiere partie du travail presente l'etude de la spectrometrie {alpha} par detecteur a semiconducteurs, un catalogue de spectres {alpha} met en evidence les avantages de cette methode. Dans la deuxieme partie on trouvera en premier lieu une nouvelle methode chimique de separation du polonium 210 ainsi que les resultats obtenus grace a cette methode. Les principaux resultats sur le

  13. A rapid method for determination of the isotopic composition of uranium samples by alpha spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Martin Sanchez, A.; Tome, F.V.; Diaz Bejarano, J.; Jurado Vargas, M. (Dept. de Fisica, Univ. Extremadura, Badajoz (Spain))

    1992-03-01

    A simple method of analyzing alpha spectra from natural and enriched or depleted uranium samples is developed. The procedure is non-iterative, and takes into consideration low-energy tail and branching-ratio corrections to accurately calculate the area corresponding to each uranium isotope ({sup 234}U, {sup 235}U, {sup 236}U, {sup 238}U) in the spectrum, and then the isotopic composition of the sample. A BASIC computer program, called ENURA, has been developed to perform all the necessary calculations to give the results together with their uncertainties. Several samples were prepared with different uranium concentrations made from standard solutions with known compositions, and the method was checked against the experimental measurements from these samples. Other series of uranium spectra were theoretically constructed using a given line shape in order to cover the required range of enriched or depleted uranium. (orig.).

  14. A rapid method for determination of the isotopic composition of uranium samples by alpha spectrometry

    Science.gov (United States)

    Sánchez, A. Martín; Tomé, F. Vera; Bejarano, J. Díaz; Vargas, M. Jurado

    1992-03-01

    A simple method of analyzing alpha spectra from natural and enriched or depleted uranium samples is developed. The procedure is non-iterative, and takes into consideration low-energy tail and branching-ratio corrections to accurately calculate the area corresponding to each uranium isotope (234U, 235U, 236U, 238U) in the spectrum, and then the isotopic composition of the sample. A BASIC computer program, called ENURA, has been developed to perform all the necessary calculations to give the results together with their uncertainties. Several samples were prepared with different uranium concentrations made from standard solutions with known compositions, and the method was checked against the experimental measurements from these samples. Other series of uranium spectra were theoretically constructed using a given line shape in order to cover the required range of enriched or depleted uranium.

  15. Derivatives of 16alpha-hydroxy-dehydroepiandrosterone with an additional 7-oxo or 7-hydroxy substituent: synthesis and gas chromatography/mass spectrometry analysis.

    Science.gov (United States)

    Pouzar, Vladimír; Cerný, Ivan; Hill, Martin; Bicíková, Marie; Hampl, Richard

    2005-10-01

    Derivatives of 16alpha-hydroxy-dehydroepiandrosterone, which have an additional oxygen substituent at position 7 (oxo or hydroxy group), were synthesized. Firstly, 17,17-dimethoxyandrost-5-ene-3beta,16alpha-diyl diacetate was prepared and then oxidized with a complex of chromium(VI) oxide and 2,5-dimethylpyrazole to the respective 7-oxo derivative. This key intermediate was both deprotected or reduced by l-Selectride or sodium borohydride in the presence of cerium(III) chloride and then deprotected to give 7-oxo, 7alpha-hydroxy and 7beta-hydroxy derivatives of 16alpha-hydroxy-dehydroepiandrosterone. The target compounds were characterized by (1)H and (13)C NMR spectra and in the form of O-methyloxime-trimethylsilyl derivatives, by gas chromatography/mass spectrometry methods.

  16. Monitoring urinary metabolites resulting from sulfur mustard exposure in rabbits, using highly sensitive isotope-dilution gas chromatography-mass spectrometry.

    Science.gov (United States)

    Nie, Zhiyong; Zhang, Yajiao; Chen, Jia; Lin, Ying; Wu, Bidong; Dong, Yuan; Feng, Jianlin; Liu, Qin; Xie, Jianwei

    2014-08-01

    A highly sensitive method for the determination of sulfur mustard (SM) metabolites thiodiglycol (TDG) and thiodiglycol sulfoxide (TDGO) in urine was established and validated using isotope-dilution negative-ion chemical ionization (NICI) gas chromatography-mass spectrometry (GC-MS). TDGO in the samples was reduced with TiCl3, and then determined together with TDG as a single analyte. The sample preparation procedures, including two solid-phase-extraction (SPE) clean-up steps, were optimized to improve the sensitivity of the method. The limits of detection (LOD) for both TDG and TDG plus TDGO (TDG + TDGO) were 0.1 ng mL(-1), and the limits of quantitation (LOQ) for both were 0.3 ng mL(-1). The method was used in a rabbit cutaneous SM exposure model. Domestic rabbits were exposed to neat liquid SM at three dosage levels (0.02, 0.05, and 0.15 LD50), and the urinary excretion of four species of hydrolysis metabolites, namely free TDG, free plus conjugated TDG (total TDG), free TDG + TDGO, and free plus conjugated TDG + TDGO (total TDG + TDGO), was evaluated to investigate the metabolic processes. The total urinary excretion profiles of the metabolites, including the peak time, time window, and dose-response and time-response relationships, were clarified. The results revealed that the concentrations of TDG and TDG + TDGO in the urine increased quickly and then decreased rapidly in the first two days after SM exposure. The cumulative amount of total TDG + TDGO excreted in urine during the first five days accounted for 0.5-1% of the applied dose of SM. It is also concluded that TDG and TDGO in urine existed mainly in free form, the levels of glucuronide and of sulfate conjugates of TDG or TDGO were very low, and most hydrolysis metabolites were present in the oxidized form (TDGO). The study indicates that the abnormal increase of TDG and TDGO excretion levels can be used as a diagnostic indicator and establishes a reference time-window for retrospective analysis and

  17. External validation of aminoglycoside models used in web calculators and clinical decision support systems after laboratory conversion to serum creatinine isotope dilution mass spectrometry assay.

    Science.gov (United States)

    Wolowich, William R; Steinberg, Jennifer G

    2012-04-01

    Models to predict gentamicin t(½) from serum creatinine (SCr) estimated creatinine clearance (CrCl) are currently being incorporated into smart-device applications and clinical decision support modules without external validation. The aim of this study was to determine whether such models remain viable after conversion to isotope dilution mass spectrometry (IDMS) SCr assay. This study analyzed data from retrospective reviews of the medical records of nonobese adults receiving the aminoglycoside gentamicin and having ≥2 evaluable serum gentamicin concentrations after laboratory IDMS SCr conversion, from January 2008 to August 2009, at a tertiary care hospital in Florida. A literature search found a number of cited aminoglycoside models. This group of models was classified as group 1. The World Wide Web was also searched for the term aminoglycoside dosing calculators, with 6 models found and referred to as group 2. Predictive performance measures were used to compare the model results with the t(½) calculated from gentamicin concentrations using the Nelder-Mead algorithm. The records of 39 patients met the inclusion criteria (23 men, 16 women; age range, 18-86 years; range of estimated CrCl, 55-115 mL/min) and provided the "gold standard" aminoglycoside t(½). A gentamicin t(½) was predicted from several published models (group 1) and from other models used in online smart-device applications (group 2) and clinical decision modules. The median (interquartile range) root mean square errors were 0.48 (0.44 to 0.65) and 0.48 (0.45 to 0.70) hours from group-1 and -2 models, respectively. The median mean relative prediction errors were 9% (-14% to +13%) and 11% (+1% to +21%) from groups 1 and 2. The median mean absolute prediction errors were 21% (19% to 28%) and 21% (20% to 30%) from groups 1 and 2. Adjusting SCr by +20% improved the predictive ability in 3 of 12 cited models and in 5 of 6 models used in applications. Models to predict gentamicin t(½) should be

  18. Contribution to the study of the geophysical behaviour of lead-210 by application of alpha spectrometry

    International Nuclear Information System (INIS)

    Nezami, M.

    1965-06-01

    A study of the changes in the lead-210 contents of rain-water and of water produced by melting polar ice has required the development of a method for dosing lead-210, an α emitter. This method is 40 times more sensitive than that which measures the lead-210 by bismuth-210, a (β emitter. The first part of the report presents the study of a spectrometry using semiconductor detectors; a catalogue of a spectra shows the advantages of this method. In the second part will be found at first a new chemical separation method for polonium-210 and the results obtained with this method. The main results obtained on the geophysical behaviour of lead-210 are the following: - the monthly lead-210 and polonium-210 contents in rain water are approximately constant with time. - in the Gif-sur-Yvette region, the clean-up by 'dry fall-out' can attain 40 to 50 per cent of the total fall-out. - a study of Antarctic ice samples makes it possible to determine an annual accumulation rate equivalent to 13.8 cm of water and to show discrepancies in the periodic concentrations which correspond to the latest maxima of solar activity. - a balance is drawn up between the radon produced by the continents and the lead-210 fall-out. (author) [fr

  19. Standard test method for radiochemical determination of uranium isotopes in soil by alpha spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This test method covers the determination of alpha-emitting uranium isotopes in soil. This test method describes one acceptable approach to the determination of uranium isotopes in soil. 1.2 The test method is designed to analyze 10 g of soil; however, the sample size may be varied to 50 g depending on the activity level. This test method may not be able to completely dissolve all forms of uranium in the soil matrix. Studies have indicated that the use of hydrofluoric acid to dissolve soil has resulted in lower values than results using total dissolution by fusion. 1.3 The lower limit of detection is dependent on count time, sample size, detector, background, and tracer yield. The chemical yield averaged 78 % in a single laboratory evaluation, and 66 % in an interlaboratory collaborative study. 1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, ass...

  20. Radionuclide content of simulated and fully radioactive SRLLL waste glasses: comparison of results from ICP-MS, gamma spectrometry and alpha spectrometry

    International Nuclear Information System (INIS)

    Wolf, S.F.; Bates, J.K.

    1995-01-01

    We have measured the transuranic content of two transuranic=doped, simulated waste glasses, using inductively coupled plasma-mass spectrometry (ICP-MS), γ-spectrometry, and α-spectrometry. Average concentrations measured by each technique were within ± 10% of the as-doped concentrations. We also report the transuranic content of three fully radioactive SRL waste glasses that were determined using γ- and α-spectrometry measurements to deconvolute isobaric interferences present in the ICP-MS analyses

  1. Application of the alpha spectrometry for the study of core sediment extracted in the San Marcos dam in Chihuahua

    International Nuclear Information System (INIS)

    Mendez G, C.; Renteria V, M.; Montero C, M. E.; Garcia T, R.

    2012-01-01

    The determination of the specific activities of 210 Po and isotopic uranium by alpha spectrometry was performed in a sediment core from San Marcos Dam. The objective of this work was to analyze the vertical distribution of isotopic uranium and 210 Po and the behavior of these radionuclides along sediment core collected from the San Marcos Dam. Sample was divided into 11 sections, in which 210 Po and isotopic uranium were determined using liquid-liquid extraction with tributyl phosphate. Furthermore, it was made a comparison between the tributyl phosphate technique and the technique of extraction chromatography using UTEVA resins for uranium. The results of specific activities for 210 Po show a trend to decrease along the core, whereas the uranium isotopic does not show a pointed trend. The results of isotopic ratios between the 234 U and 238 U show that they are close to secular equilibrium in each of the core sections. The comparison between the two uranium extraction techniques indicates that the chemical yield is better using the UTEVA technique than tributyl phosphate extraction. (Author)

  2. Application of the alpha spectrometry for the study of core sediment extracted in the San Marcos dam in Chihuahua

    Energy Technology Data Exchange (ETDEWEB)

    Mendez G, C.; Renteria V, M.; Montero C, M. E. [Centro de Investigacion en Materiales Avanzados, S. C., Miguel de Cervantes No. 120, Complejo Industrial Chihuahua, 31109 Chihuahua (Mexico); Garcia T, R., E-mail: elena.montero@cimav.edu.mx [Universidad de Sevilla, Escuela Tecnica Superior de Arquitectura, Grupo de Fisica Nuclear Aplicada, Av. Reina Mercedes s/n, 41012 Sevilla (Spain)

    2012-06-15

    The determination of the specific activities of {sup 210}Po and isotopic uranium by alpha spectrometry was performed in a sediment core from San Marcos Dam. The objective of this work was to analyze the vertical distribution of isotopic uranium and {sup 210}Po and the behavior of these radionuclides along sediment core collected from the San Marcos Dam. Sample was divided into 11 sections, in which {sup 210}Po and isotopic uranium were determined using liquid-liquid extraction with tributyl phosphate. Furthermore, it was made a comparison between the tributyl phosphate technique and the technique of extraction chromatography using UTEVA resins for uranium. The results of specific activities for {sup 210}Po show a trend to decrease along the core, whereas the uranium isotopic does not show a pointed trend. The results of isotopic ratios between the {sup 234}U and {sup 238}U show that they are close to secular equilibrium in each of the core sections. The comparison between the two uranium extraction techniques indicates that the chemical yield is better using the UTEVA technique than tributyl phosphate extraction. (Author)

  3. Measurement of short-lived radon progenies by simultaneous alpha gamma-spectrometry at the German radon reference chamber

    CERN Document Server

    Paul, A; Honig, A; Sulima, T; Buchholz, A; Keyser, U

    1999-01-01

    In the German radon reference chamber, the short-lived radon progenies are separated by a sample tube according to the attached or unattached fraction, while their activity concentration is afterwards measured by simultaneous alpha- and gamma-spectrometry. The results are expressed by the equilibrium factor F and the unattached fraction f sub p (International Commission on Radiological Protection, ICRP Publication 50, Ann. ICRP 17 (1987) 1). Both F and f sub p , can be therefore studied with respect to the full set of environmental parameters, e.g. temperature, humidity, air pressure and aerosol concentration (Honig et al., Nucl. Instr. and Meth. A 416 (1998) 525). Up to now, well-defined and stable equilibrium factors in the interval from 0.1 to 1.0 have been established. In correlation with this, the unattached fraction can be varied from 0.01 to 0.9. The sample and measuring technique for the short-lived radon progenies described in this work is the basis for fundamental studies with regard to the equilibr...

  4. Alpha spectrometry Analysis of radioisotopes of thorium and uranium in the soil (IAEA soil reference ground 375 and the natural region of Utique (Bizerte))

    International Nuclear Information System (INIS)

    Mejri, Mouna

    2008-01-01

    Since the formation of the terrestrial crust, the primordial radionuclides are present in the minerals. The main are the radioactive elemnts of the Uranium 238, of Uranium 235, of the Thorium 232 chains, Potassium 40 and the Ribidium 87. In this survey, we will present the methodology of analysis of the natural radioisotopes of uranium ( 238 U, 235 U and 234 U) and those of the thorium ( 232 Th, 230 Th and 228 Th) presents to the state of tracers in the natural soils. The method of measurement used is the alpha spectrometry. This technique is very important in the radiometric analysis, especially for the pure alpha emitters or for the low levels of radioactivity analysis. The results if analysis of the Thorium are compared to those gotten by the ICP - AES ( t he Atomic Emission Spectrometry Coupled to an inductive Plasma ) . (Author)

  5. Estimation of ultra trace plutonium isotopy ({approx_equal}10{sup -9} G) by alpha spectrometry; Estimation de l'isotopie du plutonium par spectrometrie alpha, a partir d'ultra traces ({approx_equal}10{sup -9} G) contenues dans les echantillons

    Energy Technology Data Exchange (ETDEWEB)

    Curnier, J.P.; Andrieu, G. [Cogema, 30 - Marcoule (France)

    1997-07-01

    Alpha emission spectrometry has been used to determine the activity or mass ratio between the plutonium isotopes 239 and 240 with a sensitivity of about 10%. It is nevertheless necessary to have an energy resolution of about 10 keV and an electrolytic plutonium deposit on a stainless steel sheet of about 10{sup -8} g (or 1 Bq)

  6. Determination of curium-242 by α spectrometry and mass spectrometry in spent nuclear fuels

    International Nuclear Information System (INIS)

    Chartier, F.; Aubert, M.; Degros, J.P.; Duda, J.M.

    2004-01-01

    Curium-242 is a particularly important isotope in spent nuclear fuels due to its contribution to the residual power and also of its radioactive decrease chain. The determination of its content is therefore essential to improve the knowledge of the nuclear data. According to the nature and the cooling time of the spent fuel, the 242 Cm content can be lower than the detection limit of the classically used mass spectrometric techniques. To overcome this limitation, alpha spectrometry can be advantageously used for this radionuclide of short period (T = 162.9 days). From dilute solutions of MOX fuels of short time of cooling and for which the content of 242 Cm is about a few tens of pg, the development of different successive chemical separations permitted to get sufficiently pure curium fractions to perform curium isotopic analysis by thermal ionization mass spectrometry but also the determination of the 242 Cm/ 244 Cm ratio by alpha spectrometry. The agreement on the ratios determined by the two techniques has allowed to spread the measure by alpha spectrometry to a UOX fuel of content in 242 Cm even lower. The association of the 242 Cm/ 244 Cm ratio measurement with the 244 Cm/ 238 U ratio obtained by thermal ionization mass spectrometry and isotope dilution, with a 248 Cm/ 233 U spike, permits to know the content in curium-242 in relation to uranium-238 which is used as a reference in the fuel. (author)

  7. Congener-specific determination of ultratrace levels of chlorinated and brominated polycyclic aromatic hydrocarbons in atmosphere and industrial stack gas by isotopic dilution gas chromatography/high resolution mass spectrometry method.

    Science.gov (United States)

    Jin, Rong; Liu, Guorui; Zheng, Minghui; Fiedler, Heidelore; Jiang, Xiaoxu; Yang, Lili; Wu, Xiaolin; Xu, Yang

    2017-08-04

    Isotopic dilution gas chromatography combined with high resolution mass spectrometry (GC/HRMS) has overwhelming advantages with respect to the accuracy of congener-specific ultratrace analysis of complex persistent organic pollutants (POPs) in environmental matrices. However, an isotopic dilution GC/HRMS method for analysis of chlorinated and brominated polycyclic aromatic hydrocarbons (Cl-PAHs and Br-PAHs) using 13 C-labelled congeners as internal standards has not been established. In this study, a method for identification and quantification of 38 congeners of Cl-PAHs and Br-PAHs in atmosphere and stack gas samples from waste incinerators was developed using the isotopic dilution GC/HRMS technique. The instrumental detection limits of the GC/HRMS method ranged from 0.2pg to 1.8pg for Cl-PAH congeners, and 0.7pg to 2.7pg for Br-PAH congeners, which were about three orders of magnitude lower than those of the GC/quadrupole MS method. This new method developed was also the first to enable determination of Cl-PAH and Br-PAH homologs comprising congeners with the same molecular skeleton and chlorine or bromine substitution numbers. Among the detected congeners, seven Cl-PAH congeners and thirteen Br-PAH congeners that were abundant in the atmosphere and stack gases released from waste incinerators were firstly detected in real samples and reported using the established isotopic dilution GC/HRMS method. The developed isotopic dilution GC/HRMS is significant and needed for better studying the environmental behavior and health risk of Cl-PAHs and Br-PAHs. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Determination of urea kinetics by isotope dilution with [C-13]urea and gas chromatography isotope ratio mass spectrometry (GC-IRMS) analysis

    NARCIS (Netherlands)

    Kloppenburg, Wybe; Wolthers, BG; Stellaard, F; Elzinga, H; Tepper, T; deJong, PE; Huisman, RM

    1. Stable urea isotopes can be used to study urea kinetics in humans, The use of stable urea isotopes far studying urea kinetic parameters in humans on a large scale is hampered by the high costs of the labelled material, We devised a urea dilution for measurement of the distribution volume,

  9. Determination of radium isotopes in environmental samples by gamma spectrometry, liquid scintillation counting and alpha spectrometry: a review of analytical methodology

    International Nuclear Information System (INIS)

    Jia, Guogang; Jia, Jing

    2012-01-01

    Radium (Ra) isotopes are important from the viewpoints of radiation protection and environmental protection. Their high toxicity has stimulated the continuing interest in methodology research for determination of Ra isotopes in various media. In this paper, the three most routinely used analytical techniques for Ra isotope determination in biological and environmental samples, i.e. low-background γ-spectrometry, liquid scintillation counting and α-spectrometry, were reviewed, with emphasis on new methodological developments in sample preparation, preconcentration, separation, purification, source preparation and measurement techniques. The accuracy, selectivity, traceability, applicability and minimum detectable activity (MDA) of the three techniques were discussed. It was concluded that the MDA (0.1 mBq L −1 ) of the α-spectrometry technique coupled with chemical separation is about two orders of magnitude lower than that of low-background HPGe γ-spectrometry and LSC techniques. Therefore, when maximum sensitivity is required, the α-spectrometry technique remains the first choice. - Highlights: ► A review is made for determination of Ra isotopes in environmental samples. ► Gamma spectrometry, LSC and a-spectrometry are the main concerned radiometric approach. ► Sample preparation, preconcentration, separation and source preparation are discussed. ► The methods can analyse air, water, seawater, soil, sediment and foodstuffs samples. ► Some new data obtained recently from our laboratory for Ra method study are included.

  10. An automatic versatile system integrating solid-phase extraction with ultra-high performance liquid chromatography-tandem mass spectrometry using a dual-dilution strategy for direct analysis of auxins in plant extracts.

    Science.gov (United States)

    Zhong, Qisheng; Qiu, Xiongxiong; Lin, Caiyong; Shen, Lingling; Huo, Yin; Zhan, Song; Yao, Jinting; Huang, Taohong; Kawano, Shin-ichi; Hashi, Yuki; Xiao, Langtao; Zhou, Ting

    2014-09-12

    An automatic versatile system which integrated solid phase extraction (SPE) with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed. Diverse commercial SPE columns can be used under an ambient pressure in this online system realized by a dual-dilution strategy. The first dilution enabled the direct injection of complex samples with minimal pretreatment, and the second dilution realized direct introduction of large volume of strong eluent into the UHPLC column without causing peak broadening or distortion. In addition, a post-column compensation mode was also designed for the matrix-effects evaluation. The features of the online system were systematically investigated, including the dilution effect, the capture of desorption solution, the column-head stacking effect and the system recovery. Compared with the offline UHPLC system, this online system showed significant advantages such as larger injection volume, higher sensitivity, shorter analysis time and better repeatability. The feasibility of the system was demonstrated by the direct analysis of three auxins from different plant tissues, including leaves of Dracaena sanderiana, buds and petals of Bauhinia. Under the optimized conditions, the whole analysis procedure took only 7min. All the correlation coefficients were greater than 0.9987, the limits of detection and the limits of quantitation were in the range of 0.560-0.800ng/g and 1.80-2.60ng/g, respectively. The recoveries of the real samples ranged from 61.0 to 117%. Finally, the post-column compensation mode was applied and no matrix-effects were observed under the analysis conditions. The automatic versatile system was rapid, sensitive and reliable. We expect this system could be extended to other target analytes in complex samples utilizing diverse SPE columns. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Dilution Confusion: Conventions for Defining a Dilution

    Science.gov (United States)

    Fishel, Laurence A.

    2010-01-01

    Two conventions for preparing dilutions are used in clinical laboratories. The first convention defines an "a:b" dilution as "a" volumes of solution A plus "b" volumes of solution B. The second convention defines an "a:b" dilution as "a" volumes of solution A diluted into a final volume of "b". Use of the incorrect dilution convention could affect…

  12. Direct determination of the estrogenic compounds 8-prenylnaringenin, zearalenone, alpha- and beta-zearalenol in beer by liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Maragou, Niki C; Rosenberg, Erwin; Thomaidis, Nikolaos S; Koupparis, Michael A

    2008-08-15

    A novel LC-ESI-MS method for the simultaneous determination of four of the most significant estrogenic compounds naturally occurring in beer, 8-prenylnaringenin (8-PN), zearalenone (ZON), alpha-zearalenol (alpha-ZOL) and beta-zearalenol (beta-ZOL) which requires minimal sample preparation was developed using a chemometric approach. Experimental design was applied to assess the effects of the LC-ESI-MS parameters (mobile phase flow rate, drying gas flow, nebuliser pressure and capillary potential) on the obtained signal and to optimize the values in order to provide maximum sensitivity and detectability. The proposed method is simple, consisting only of degassing the beer and diluting with water (1:1, v/v) before injection. Comparison between the two internal standards used, zearalanone (ZAN) and 4,2'-dihydroxychalcone (4,2'-DHC), showed that ZAN performs better as internal standard not only for the mycotoxins but for 8-PN as well, giving lower % RSDs. Under inter-day conditions mean recoveries were 107% for ZON, 87.8% for alpha-ZOL, 72.8% for beta-ZOL, and 77.5% for 8-PN. The corresponding % RSDs ranged between 5.0 and 8.0. The method limits of detection were 1.3, 1.4, 1.0 and 0.8 ng mL(-1) for ZON, alpha-ZOL, beta-ZOL and 8-PN, respectively. The method was applied to 15 beer samples obtained from local supermarkets and the concentration of the phytoestrogen 8-PN in beer ranged between <0.8 and 38.6 ng mL(-1), while neither ZON nor its metabolites, alpha-ZOL and beta-ZOL, were detected.

  13. Determination of 222Rn in fresh water: development of a robust method of analysis by alpha/beta separation liquid scintillation spectrometry.

    Science.gov (United States)

    Pates, Jacqueline M; Mullinger, Neil J

    2007-01-01

    Liquid scintillation spectrometry is used widely for determining (222)Rn in natural waters; however, the benefits of alpha/beta separation have not been fully explored. The extractants toluene and Ultima Gold F were compared, and both performed well for a range of extreme waters. A robust method for calibrating extraction and counting efficiencies has been developed. Detection limits are 20 mBql(-1) (toluene) and 16 mBql(-1) (UGF) for a 60 min count and 600-ml sample, halving the required sample volume.

  14. Gas chromatography-mass spectrometry microanalysis of alpha- and gamma-tocopherol in plasma and whole blood.

    Science.gov (United States)

    Zerbinati, C; Galli, F; Regolanti, R; Poli, G; Iuliano, L

    2015-06-15

    Assessing vitamin E status in humans is critical for nutritional evaluation and verification of clinical and biological compliance of supplemented subjects. An accurate analytical method for measuring the two main vitamin E isoforms, i.e. α- and γ-tocopherol (α- and γ-TOH) in small volumes of plasma can facilitate the application of this analysis to clinical trials and in situations where a limited amount of sample is available. We have developed a micro method, which uses only 5 μL plasma, based on isotope dilution, trimethylsilation and GC-MS. The method was validated according to the guidelines of the International Conference on Harmonization of analytical procedures. The method was also applied to 5 μL of whole blood for the potential use in conditions were the availability of specimens is limited. Accurate quantitation of α-TOH and γ-TOH was achieved at levels ≥ 0.417 μM and ≥ 0.007 μM, respectively. Within-day coefficient of variation was 1.31% and 4.70% for α-TOH and γ-TOH, respectively. Between-day coefficient of variation was 1.32% and 2.88% for α-TOH and γ-TOH, respectively. Recovery, assessed at three concentration levels, ranged 98-103% and 100-102% for α-TOH and γ-TOH, respectively. The method allowed the detection of α-TOH and γ-TOH in 5 μL whole blood and in membranes of red blood cells washed from 5 μL of blood as well. The analytical performance was assessed in plasma from a cohort of Italian healthy subjects (n = 205). The mean plasma concentrations were 28.01 ± 6.31 and 0.68 ± 0.48 μM (mean ± SD) for α-TOH and γ-TOH, respectively. Alpha-TOH correlated with total cholesterol (r = 0.617, p < 0.0001) and triglycerides (r = 0.420, p < 0.0001) while γ-TOH correlated modestly with total cholesterol (r = 0.213, p < 0.0001) but not with triglycerides. γ-TOH, but not α-TOH, was significantly lower in smokers than in non-smokers (0.72 ± 0.50 vs. 0.56 ± 0.37, μM, mean ± SD, p = 0.017). Given the high sensitivity, the

  15. Quantitation of metabolites of the nerve agents sarin, soman, cyclohexylsarin, VX, and Russian VX in human urine using isotope-dilution gas chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Barr, John R; Driskell, W J; Aston, Linda S; Martinez, Rodolfo A

    2004-01-01

    Organophosphorus nerve agents are among the most toxic organic compounds known and continue to be a threat for both military and terrorist use. We have developed an isotope-dilution gas chromatography-tandem mass spectrometric (GC-MS-MS) method for quantitating the urinary metabolites of the organophosphorus nerve agents sarin (GB), soman (GD), VX, Russian VX (RVX), and cyclohexylsarin (GF). Urine samples were acidified, extracted into ether-acetonitrile, derivatized by methylation with diazomethane, and analyzed by GC-MS-MS. The limits of detection were less than 1 micro g/L for all analytes.

  16. Assessment of the amount of body water in the Red Knot (Calidris canutus) : An evaluation of the principle of isotope dilution with 2H, 17O, and 18O as easured with laser spectrometry and isotope ratio mass spectrometry

    NARCIS (Netherlands)

    Kerstel, Erik R.T.; Piersma, Theunis A.J.; Gessaman, G. Jim; Dekinga, Anne; Meijer, Harro A.J.; Visser, G. Henk

    We have used the isotope dilution technique to study changes in the body composition of a migratory shorebird species (Red Knot, Calidris canutus) through an assessment of the amount of body water in it. Birds were quantitatively injected with a dose of water with elevated concentrations of H-2,

  17. Measurement of selected polybrominated diphenyl ethers, polybrominated and polychlorinated biphenyls, and organochlorine pesticides in human serum and milk using comprehensive two-dimensional gas chromatography isotope dilution time-of-flight mass spectrometry.

    Science.gov (United States)

    Focant, Jean-François; Sjödin, Andreas; Turner, Wayman E; Patterson, Donald G

    2004-11-01

    A new method using comprehensive two-dimensional gas chromatography and isotope dilution time-of-flight mass spectrometry (GCxGC-IDTOFMS) for the simultaneous measurement of selected polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and brominated flame retardants is presented. In contrast to the reference methods based on classical GC/MS, a single injection of the extract containing all compounds of interest results in accurate identification and quantification. Using GCxGC ensures the chromatographic separation of most compounds, and TOFMS allows mass spectral deconvolution of coeluting compounds as well as the use of (13)C-labeled internal standards for quantification. Isotope ratio measurements of the most intense ions for both native and labels ensure the required specificity. The use of this new method with an automated sample preparation procedure developed at the Centers for Disease Control and Prevention (CDC) for the analysis of human serum and milk compared favorably to conventional isotope-dilution one-dimensional gas chromatography-high-resolution mass spectrometry (GC-IDHRMS) for the different human serum and milk pools tested. The instrumental detection limits ranged between 0.5 pg/microL and 10 pg/microL and the method detection limits ranged between 1 and 15 pg/microL (N = 59 analytes). The reproducibility of the method was almost as good as with GC-IDHRMS, the relative standard deviations ranging between 1 and 11% for OCPs measured in human serum. OCP, PBDE, and PCB levels measured using the two methods were highly correlated, and the deviations between the two methods were below 20% for most analytes with concentrations above 1 ng/g milk lipids.

  18. A workflow for multiclass determination of 256 pesticides in essential oils by liquid chromatography tandem mass spectrometry using evaporation and dilution approaches: Application to lavandin, lemon and cypress essential oils.

    Science.gov (United States)

    Fillatre, Yoann; Rondeau, David; Daguin, Antoine; Communal, Pierre-Yves

    2016-01-01

    This paper describes the determination of 256 multiclass pesticides in cypress and lemon essential oils (EOs) by the way of liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS) analysis using the scheduled selected reaction monitoring mode (sSRM) available on a hybrid quadrupole linear ion trap (QLIT) mass spectrometer. The performance of a sample preparation of lemon and cypress EOs based on dilution or evaporation under nitrogen assisted by a controlled heating were assessed. The best limits of quantification (LOQs) were achieved with the evaporation under nitrogen method giving LOQs≤10µgL(-1) for 91% of the pesticides. In addition the very satisfactory results obtained for recovery, repeatability and linearity showed that for EOs of relatively low evaporation temperature, a sample preparation based on evaporation under nitrogen is well adapted and preferable to dilution. By compiling these results with those previously published by some of us on lavandin EO, we proposed a workflow dedicated to multiresidue determination of pesticides in various EOs by LC-ESI/sSRM. Among the steps involved in this workflow, the protocol related to mass spectrometry proposes an alternative confirmation method to the classical SRM ratio criteria based on a sSRM survey scan followed by an information-dependent acquisition using the sensitive enhanced product ion (EPI) scan to generate MS/MS spectra then compared to a reference. The submitted workflow was applied to the case of lemon EOs samples highlighting for the first time the simultaneous detection of 20 multiclass pesticides in one EO. Some pesticides showed very high concentration levels with amounts greatly exceeding the mgL(-1). Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Sm isotope composition and Sm/Eu ratio determination in an irradiated 153Eu sample by ion exchange chromatography-quadrupole inductively coupled plasma mass spectrometry combined with double spike isotope dilution technique

    International Nuclear Information System (INIS)

    Bourgeois, M.; Isnard, H.; Gourgiotis, A.; Stadelmann, G.; Gautier, C.; Mialle, S.; Nonell, A.; Chartier, F.

    2011-01-01

    Within the framework of the research undertaken by the French Atomic Energy Commission on transmutation of long-lived radionuclides, targets of highly enriched actinides and fission products were irradiated in the fast neutron reactor Phenix. Precise and accurate measurements of the isotopic and elemental composition of the enriched elements are therefore required. In order to obtain the uncertainties of several per mil and to reduce handling time and exposure to analyst on radioactive material, the on-line coupling of ion exchange chromatography with quadrupole inductively coupled plasma mass spectrometry has been associated with the technique of the double spike isotope dilution. We present in this paper the results obtained on an irradiated sample of Europium oxide powder (enriched at 99.13% in 153 Eu). After irradiation of around 5 mg of Eu 2 O 3 powder the theoretical calculations predict the formation of several micrograms of gadolinium and samarium isotopes. In relation to the very high activity of the sample after irradiation and the very low quantity of Sm formed, the on-line ion exchange chromatography separation of Gd, Sm and Eu before Sm isotope ratio measurements has been developed for the quantification of the 152 Sm/ 153 Eu ratio. These on-line measurements were associated with the double spike isotope dilution technique after calibration of a 147 Sm/ 151 Eu spike solution. The external reproducibility of Sm isotopic ratios was determined to be around 0.5% (2 σ) resulting in a final uncertainty on the 152 Sm/ 153 Eu ratio of around 1% (2 σ). These on-line measurements present therefore a robust and high-throughput alternative to the thermal-ionisation mass spectrometry technique used so far in combination with off-line chromatographic separation, particularly in nuclear applications where characterisation of high activity sample solutions is required. (authors)

  20. Development of multi-residue method for the determination of pesticides in cereal matrices by isotopic dilution associated to liquid chromatography coupled to tandem mass spectrometry after pressurized liquid extraction

    International Nuclear Information System (INIS)

    El Mrabet, Khadija

    2008-01-01

    Pesticides are nowadays considered as toxic for human health. The maximal residues levels authorized in water and foodstuff are more and more strict. Therefore, selective analytical techniques are necessary for their identification and their quantification. The aim of this thesis was to develop a multi-residue method for the determination of pesticides by isotopic dilution associated to liquid chromatography (LC) coupled with tandem mass spectrometry (MS 2 ) after pressurized liquid extraction. In a first step, an analysis method of phenyl-ureas and triazines in groundwater by isotopic dilution associated to LC/MS 2 after solid phase extraction has been developed. The method has been validated and evaluated by participating to an inter-laboratory study. Concerning cereals, an extraction method of pesticides associated to an analysis by LC/MS 2 has been developed for thirty-eight pesticides representative of twenty-six chemicals families and fourteen labeled compounds in wheat. The analysis has been carried out in reversed phase chromatography. Separation and detection conditions have been optimized. A global analytical protocol consisting of a pressurized liquid extraction step using acetonitrile at 100 deg. C and at 100 bars and followed by purification step of the resulting extract on a polymeric sorbent was developed. The developed method enables to extract thirty-eight pesticides and fourteen labeled compounds from wheat with recovery yield about 85% (RSD =4%, n=3). Moreover, the results show that the application of isotopic dilution can be complex. Although some improvements need to be added regarding experimentation of aged matrices or contaminated samples, the potential of the method has been demonstrated. (author) [fr

  1. Analysis of trace metals (Cu, Cd, Pb, and Fe) in seawater using single batch nitrilotriacetate resin extraction and isotope dilution inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Lee, Jong-Mi; Boyle, Edward A.; Echegoyen-Sanz, Yolanda; Fitzsimmons, Jessica N.; Zhang Ruifeng; Kayser, Richard A.

    2011-01-01

    A simple and accurate low-blank method has been developed for the analysis of total dissolved copper, cadmium, lead, and iron in a small volume (1.3-1.5 mL per element) of seawater. Pre-concentration and salt-separation of a stable isotope spiked sample are achieved by single batch extraction onto nitrilotriacetate (NTA)-type Superflow chelating resin beads (100-2400 beads depending on the element). Metals are released into 0.1-0.5 M HNO 3 , and trace metal isotope ratios are determined by ICPMS. The benefit of this method compared to our previous Mg(OH) 2 coprecipitation method is that the final matrix is very dilute so cone-clogging and matrix sensitivity suppression are minimal, while still retaining the high accuracy of the isotope dilution technique. Recovery efficiencies are sensitive to sample pH, number of resin beads added, and the length of time allowed for sample-resin binding and elution; these factors are optimized for each element to yield the highest recovery. The method has a low procedural blank and high sensitivity sufficient for the analysis of pM-nM open-ocean trace metal concentrations. Application of this method to samples from the Bermuda Atlantic Time-Series Study station provides oceanographically consistent Cu, Cd, Pb, and Fe profiles that are in good agreement with other reliable data for this site. In addition, the method can potentially be modified for the simultaneous analysis of multiple elements, which will be beneficial for the analysis of large number of samples.

  2. Analysis of trace metals (Cu, Cd, Pb, and Fe) in seawater using single batch nitrilotriacetate resin extraction and isotope dilution inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Mi [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Boyle, Edward A., E-mail: eaboyle@mit.edu [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Echegoyen-Sanz, Yolanda; Fitzsimmons, Jessica N. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Zhang Ruifeng [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062 (China); Kayser, Richard A. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2011-02-07

    A simple and accurate low-blank method has been developed for the analysis of total dissolved copper, cadmium, lead, and iron in a small volume (1.3-1.5 mL per element) of seawater. Pre-concentration and salt-separation of a stable isotope spiked sample are achieved by single batch extraction onto nitrilotriacetate (NTA)-type Superflow chelating resin beads (100-2400 beads depending on the element). Metals are released into 0.1-0.5 M HNO{sub 3}, and trace metal isotope ratios are determined by ICPMS. The benefit of this method compared to our previous Mg(OH){sub 2} coprecipitation method is that the final matrix is very dilute so cone-clogging and matrix sensitivity suppression are minimal, while still retaining the high accuracy of the isotope dilution technique. Recovery efficiencies are sensitive to sample pH, number of resin beads added, and the length of time allowed for sample-resin binding and elution; these factors are optimized for each element to yield the highest recovery. The method has a low procedural blank and high sensitivity sufficient for the analysis of pM-nM open-ocean trace metal concentrations. Application of this method to samples from the Bermuda Atlantic Time-Series Study station provides oceanographically consistent Cu, Cd, Pb, and Fe profiles that are in good agreement with other reliable data for this site. In addition, the method can potentially be modified for the simultaneous analysis of multiple elements, which will be beneficial for the analysis of large number of samples.

  3. Development and validation of a new analytical method for the determination of 1,4-dichlorobenzene in honey by gas chromatography-isotope dilution mass spectrometry after steam-distillation.

    Science.gov (United States)

    Botitsi, E V; Kormali, P N; Kontou, S N; Economou, A; Tsipi, D F

    2006-10-02

    A simple, fast, sensitive and robust analytical method using gas chromatography (GC)-isotope dilution mass spectrometry (MS) was developed and validated for the identification and quantification of 1,4-dichlorobenzene (p-DCB) residues in honey samples. The proposed methodology is based on steam-distillation using a Clevenger-type apparatus followed by gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring (SIM) mode employing the isotopically labeled analogue d4-1,4-dichlorobenzene (d4-p-DCB) as internal standard (IS). Validation of the method was performed in two different GC-MS systems, using quadrupole MS (QMS) and ion-trap MS (ITMS) detectors, with no statistically significant differences between two. Recoveries were better than 91% with percent relative standard deviations lower than 12%. The instrumental limits of detection were 1 microg kg(-1) in the GC-ITMS system and 0.6 microg kg(-1) in the GC-QMS system. The expanded uncertainty was estimated as 17% at the currently accepted "action level" of 10 microg kg(-1). The method was applied to the analysis of 310 honey samples in an extensive national monitoring study. A quality control (QC) system applied during the assays has demonstrated a good performance and long-term stability over a period of more than 8 months of continuous operation.

  4. Comparison of the analytical methods used to determine natural and artificial radionuclides from environmental samples by gamma, alpha and beta spectrometry

    DEFF Research Database (Denmark)

    Pöllänen, Roy; Virtanen, Sinikka; Kämäräinen, Meerit

    In CAMNAR, an extensive interlaboratory exercise on the analytical methods used to determine several radionuclides present in the environmental samples was organized. Activity concentration of different natural radionuclides, such as Rn-222, Pb-210, Po-210, K-40, Ra-226, Ra-228 and isotopes of ur...... Nordic and European countries participated in the intercomparison. Extraordinary variation between the results reported by different laboratories were revealed for some radionuclides indicating the need of future intercomparisons especially in the case of natural water samples.......In CAMNAR, an extensive interlaboratory exercise on the analytical methods used to determine several radionuclides present in the environmental samples was organized. Activity concentration of different natural radionuclides, such as Rn-222, Pb-210, Po-210, K-40, Ra-226, Ra-228 and isotopes...... of uranium, in addition to artificial Cs-137 and Am-241 were analysed from lake sediment samples and drinking water. The measurement techniques were gamma-ray spectrometry, alpha spectrometry, liquid scintillation counting and inductively coupled plasma mass spectrometry. Twenty six laboratories from nine...

  5. Isotope dilution mass spectrometry as the primary method of measurement for the amount of matter. Application to cadmium determination in biological materials and comparison with instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Munoz, Luis; Gras, Nuri; Quejido, Alberto; Ferrada, Carlos

    2001-01-01

    A primary method of measurement as defined by the Consultative Committee on the Quantity of Matter (Comite Consultatif pour la Quantite de Matiere, CCQM) of the International Bureau of Weights and Measurements (Bureau International des Poids et Mesures, BIPM), is one whose measurement process is perfectly known, has valid theoretical foundations and is fully described and answers to an equation that relates what is measured with what is intended to be measured without any significant empirical correction factors. It is also a method that has insignificant systematic errors, where only magnitudes from the International System of Units (SI) are used and where, preferably, the uncertainties are small ones. They are, therefore, procedures that do not need instrumental calibration. The absolute methods of measurement allow a chain of traceability to be formed between the result obtained and the magnitude of the SI assigned to what is measured. So the results are said to be traceable to the SI. One of the methods that meets these requirements and is recognized as the primary method by the CCQM is Isotope Dilution Mass Spectrometry (IDMS). Through a project of Technical Cooperation with the International Atomic Energy Agency in the area of Chemical Metrology, the CCHEN obtained training in CIEMAT, Spain, in IDMS and its applications to the analysis of biological samples. This work describes the first experience carried out entirely in Chilean laboratories, applying IDMS to the determination of cadmium in the biological reference materials Oyster Tissue 15566-A from the NIST, United States, Dogfish Liver, DOLT-2 from the NRC-CNRC, Canada and Poplar Leaves GBW07604 from the NRCC, China. The samples were traced with an isotope enriched spike 111 Cd and then shaken to obtain the isotopic exchange. Once dissolved, the isotopic relationship 111 Cd/ 114 Cd was determined in the samples using mass spectrometry with plasma source. These results were compared with those obtained

  6. Introduction to Body Composition Assessment Using the Deuterium Dilution Technique with Analysis of Urine Samples by Isotope Ratio Mass Spectrometry (French Edition)

    International Nuclear Information System (INIS)

    2013-01-01

    The IAEA has fostered the more widespread use of a stable isotope technique to assess body composition in different population groups to address priority areas in public health nutrition in Member States. It has done this by supporting national and regional nutrition projects through its technical cooperation programme and coordinated research projects over many years. This publication was developed by an international group of experts to provide practical hands-on guidance in the use of this technique in settings where analysis of stable isotope ratios in biological samples is to be made by isotope ratio mass spectrometry. The publication is targeted at new users of this technique, for example nutritionists, analytical chemists and other professionals. More detailed information on the theoretical background and the practical applications of state of the art methodologies to monitor changes in body composition can be found in IAEA Human Health Series No. 3, Assessment of Body Composition and Total Energy Expenditure in Humans by Stable Isotope Techniques

  7. Simultaneous determination of 11 β-agonists in human urine using high-performance liquid chromatography/tandem mass spectrometry with isotope dilution.

    Science.gov (United States)

    Wang, Xiaoli; Guo, Tao; Wang, Shanshan; Yuan, Jinpeng; Zhao, Rusong

    2015-04-01

    The misuse of β-agonists constitutes a potential risk to public health and has been forbidden in many countries. In this study, we describe a method for specific, sensitive and rapid detection of β-agonists in human urine. Urine samples were extracted with ethyl acetate, without any additional purification step, and analyzed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) with Clenbuterol-D9 and Salbuterol-D3 as internal standards. The intra- and interday precision values of the method were all application of UPLC-MS-MS method in β-agonists detection of human urine will be helpful in veterinary control of β-agonists and for studying the effect of β-agonists on human health. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Phenylboronic Acid Solid Phase Extraction Cleanup and Isotope Dilution Liquid Chromatography-Tandem Mass Spectrometry for the Determination of Florfenicol Amine in Fish Muscles.

    Science.gov (United States)

    Sin, Della Wai-Mei; Ho, Clare; Wong, Yiu-Tung

    2015-01-01

    Florfenicol (FFC) residues in foods are regulated as the sum of florfenicol and its metabolites measured as florfenicol amine (FFA). An isotope dilution LC-MS/MS method utilizing phenylboronic acid (PBA) SPE cleanup is established for the accurate determination of FFA in fish muscles (i.e., salmon and tilapia) after acid catalyzed hydrolysis. Comparisons of the PBA SPE cleanup procedure with other cleanup procedures such as mixed-mode cationic (MCX) SPE and solid supported liquid-liquid extraction were performed. Quantification of FFA in fish muscles was accomplished by using matrix-matched calibration with FFA-D3 as the internal standard. The method was validated with FFA fortified fish muscles at three different levels (50, 100, and 200 μg/kg). Conversion of FFC to FFA by acid catalyzed hydrolysis was evaluated and found to be ≥88%. The recoveries of FFA in fish muscles at the three fortification levels ranged from 89 to 106%, and RSDs were ≤9% in all cases. The LOD values in salmon and tilapia muscles were 0.13 and 1.64 μg/kg, respectively. The LOQ values in salmon and tilapia muscles were 0.29 and 4.13 μg/kg, respectively. This method is suitable for the application in routine control of FFC in fishes according to its residue definition.

  9. Development of a routine analysis of 4-mercapto-4-methylpentan-2-one in wine by stable isotope dilution assay and mass tandem spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Dagan, Laurent; Reillon, Florence; Roland, Aurélie; Schneider, Rémi, E-mail: remi@nyseos.fr

    2014-04-01

    Highlights: • We proposed a routine method to analyze the 4-methyl-4-mercaptopentan-2-one in wine. • We developed the first method with sensitivity below the 4MMP perception threshold. • We obtained an accurate method by using the stable isotope dilution assay approach. Abstract: The 4-mercapto-4-methylpentan-2-one (4MMP) is a key aroma compound in wines, especially in Sauvignon Blanc ones. Its accurate quantification is quite difficult due to its traces levels and its reactivity in wine conferred by the thiol function. In this paper, we proposed a new method for its quantification in wine without any sample preparation, based on automated derivatization procedure by methoximation and SIDA–SPME–GC–MS/MS analysis. The derivatization procedure was adapted from a previously published method in order to decrease the amount of reagents and the volume of wine (only 3 mL are required). The use of SPME and the detection conditions have also been optimized to reach the best sensitivity as possible. The method was then validated according to the International Organization of Vine and Wine recommendations and exhibited excellent performances. Indeed, this method allowed us to quantify the 4MMP in wine at traces levels (LOD = 0.19 ng L₅⁻¹) with reproducible results (RSD < 15%) and a very good accuracy (recovery = 102%)

  10. Development of a routine analysis of 4-mercapto-4-methylpentan-2-one in wine by stable isotope dilution assay and mass tandem spectrometry

    International Nuclear Information System (INIS)

    Dagan, Laurent; Reillon, Florence; Roland, Aurélie; Schneider, Rémi

    2014-01-01

    Highlights: • We proposed a routine method to analyze the 4-methyl-4-mercaptopentan-2-one in wine. • We developed the first method with sensitivity below the 4MMP perception threshold. • We obtained an accurate method by using the stable isotope dilution assay approach. - Abstract: The 4-mercapto-4-methylpentan-2-one (4MMP) is a key aroma compound in wines, especially in Sauvignon Blanc ones. Its accurate quantification is quite difficult due to its traces levels and its reactivity in wine conferred by the thiol function. In this paper, we proposed a new method for its quantification in wine without any sample preparation, based on automated derivatization procedure by methoximation and SIDA–SPME–GC–MS/MS analysis. The derivatization procedure was adapted from a previously published method in order to decrease the amount of reagents and the volume of wine (only 3 mL are required). The use of SPME and the detection conditions have also been optimized to reach the best sensitivity as possible. The method was then validated according to the International Organization of Vine and Wine recommendations and exhibited excellent performances. Indeed, this method allowed us to quantify the 4MMP in wine at traces levels (LOD = 0.19 ng L −1 ) with reproducible results (RSD < 15%) and a very good accuracy (recovery = 102%)

  11. Precision of glucose measurements in control sera by isotope dilution/mass spectrometry: proposed definitive method compared with a reference method

    International Nuclear Information System (INIS)

    Pelletier, O.; Arratoon, C.

    1987-01-01

    This improved isotope-dilution gas chromatographic/mass spectrometric (GC/MS) method, in which [ 13 C]glucose is the internal standard, meets the requirements of a Definitive Method. In a first study with five reconstituted lyophilized sera, a nested analysis of variance of GC/MS values indicated considerable among-vial variation. The CV for 32 measurements per serum ranged from 0.5 to 0.9%. However, concentration and uncertainty values (mmol/L per gram of serum) assigned to one serum by the NBS Definitive Method (7.56 +/- 0.28) were practically identical to those obtained with the proposed method (7.57 +/- 0.20). In the second study, we used twice more [ 13 C]glucose diluent to assay four serum pools and two lyophilized sera. The CV ranged from 0.26 to 0.5% for the serum pools and from 0.28 to 0.59% for the lyophilized sera. In comparison, results by the hexokinase/glucose-6-phosphate dehydrogenase reference method agreed within acceptable limits with those by the Definitive Method but tended to be slightly higher (up to 3%) for lyophilized serum samples or slightly lower (up to 2.5%) for serum pools

  12. DMSO Assisted Electrospray Ionization for the Detection of Small Peptide Hormones in Urine by Dilute-and-Shoot-Liquid-Chromatography-High Resolution Mass Spectrometry

    Science.gov (United States)

    Judák, Péter; Grainger, Janelle; Goebel, Catrin; Van Eenoo, Peter; Deventer, Koen

    2017-08-01

    The mobile phase additive (DMSO) has been described as a useful tool to enhance electrospray ionization (ESI) of peptides and proteins. So far, this technique has mainly been used in proteomic/peptide research, and its applicability in a routine clinical laboratory setting (i.e., doping control analysis) has not been described yet. This work provides a simple, easy to implement screening method for the detection of doping relevant small peptides (GHRPs, GnRHs, GHS, and vasopressin-analogues) with molecular weight less than 2 kDa applying DMSO in the mobile phase. The gain in sensitivity was sufficient to inject the urine samples after a 2-fold dilution step omitting a time consuming sample preparation. The employed analytical procedure was validated for the qualitative determination of 36 compounds, including 13 metabolites. The detection limits (LODs) ranged between 50 and 1000 pg/mL and were compliant with the 2 ng/mL minimum detection level required by the World Anti-Doping Agency (WADA) for all the target peptides. To demonstrate the feasibility of the work, urine samples obtained from patients who have been treated with desmopressin or leuprolide and urine samples that have been declared as adverse analytical findings were analyzed.

  13. Application of MALDI-TOF mass spectrometry for study on fibrillar and oligomeric aggregates of alpha-synuclein

    NARCIS (Netherlands)

    Severinovskaya, O. V.; Kovalska, V B; Losytskyy, M Yu; Cherepanov, V. V.; Subramaniam, V.; Yarmoluk, S M

    2014-01-01

    Aim. To study the α-synuclein (ASN) aggregates of different structural origin, namely amyloid fibrils and spherical oligomers, in comparison with a native protein. Methods. MALDI TOF mass spectrometry and atomic force microscopy (AFM). Results. The mass spectra of native and fibrillar ASN have

  14. Implantation of alpha spectrometry methodology for the determination of U and Th isotopes in igneous rocks: application to the study of radioactive desequilibrium in the Trindade Island, Brazil

    International Nuclear Information System (INIS)

    Santos, Rosana Nunes dos

    2001-01-01

    This work describes the implementation of experimental procedures for alpha spectrometry measurement of 238 U, 234 U and 230 Th activities in silicates. The best experimental conditions were defined using 233 U, 232 U and 229 Th radioactive tracers and simulating the usual conditions found in processing silicates. The chemical procedures consists of the following steps: radioactive tracer addition and sample dissolution by acid digestion, U and Th pre-concentration by co-precipitation, element separation and purification by ion exchange chromatography and electrodeposition in inox steel disks. In order to evaluate its effectiveness, the procedure was applied to the Brazilian geological standards BB-1 (basalt) and GB-1 (granite). The obtained chemical yields for uranium and thorium are of about 60% and 70%, respectively, for both matrices. The described methodology furnishes activity measurements with less than 4% relative precision and accuracies of about 1%, that are essential for petrogenetic applications. The 238 U and 232 Th series disequilibrium conditions were investigated by alpha spectrometry, together with neutron activation analysis and natural gamma-ray spectrometry. 234 U/ 238 U, 238 U/ 232 Th and 230 Th/ 232 Th activity ratios and the 234 Th, 214 Pb, 214 Bi, 235 U, 228 Ac, 212 Pb, 212 Bi and 208 Tl specific activities were obtained. These results were interpreted with the help of additional constraints given by the larger and smaller elements concentrations, measured by X-ray fluorescence. The 232 Th series is in secular radioactive equilibrium in all analysed samples. In the case of the 238 U series, the equilibrium condition was verified, as expected, in the oldest rocks from the Trindade Island (Trindade Complex and Desejado Sequence). On the other hand, the results show that, in the samples from the last three volcanic episodes in the island (Morro Vermelho Formation, Valado Formation and Vulcao do Paredao), the 230 Th and 238 U are not in

  15. Identification and quantification of DNA repair protein apurinic/apyrimidinic endonuclease 1 (APE1 in human cells by liquid chromatography/isotope-dilution tandem mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Güldal Kirkali

    Full Text Available Unless repaired, DNA damage can drive mutagenesis or cell death. DNA repair proteins may therefore be used as biomarkers in disease etiology or therapeutic response prediction. Thus, the accurate determination of DNA repair protein expression and genotype is of fundamental importance. Among DNA repair proteins involved in base excision repair, apurinic/apyrimidinic endonuclease 1 (APE1 is the major endonuclease in mammals and plays important roles in transcriptional regulation and modulating stress responses. Here, we present a novel approach involving LC-MS/MS with isotope-dilution to positively identify and accurately quantify APE1 in human cells and mouse tissue. A completely (15N-labeled full-length human APE1 was produced and used as an internal standard. Fourteen tryptic peptides of both human APE1 (hAPE1 and (15N-labeled hAPE1 were identified following trypsin digestion. These peptides matched the theoretical peptides expected from trypsin digestion and provided a statistically significant protein score that would unequivocally identify hAPE1. Using the developed methodology, APE1 was positively identified and quantified in nuclear and cytoplasmic extracts of multiple human cell lines and mouse liver using selected-reaction monitoring of typical mass transitions of the tryptic peptides. We also show that the methodology can be applied to the identification of hAPE1 variants found in the human population. The results describe a novel approach for the accurate measurement of wild-type and variant forms of hAPE1 in vivo, and ultimately for defining the role of this protein in disease development and treatment responses.

  16. Standard dilution analysis.

    Science.gov (United States)

    Jones, Willis B; Donati, George L; Calloway, Clifton P; Jones, Bradley T

    2015-02-17

    Standard dilution analysis (SDA) is a novel calibration method that may be applied to most instrumental techniques that will accept liquid samples and are capable of monitoring two wavelengths simultaneously. It combines the traditional methods of standard additions and internal standards. Therefore, it simultaneously corrects for matrix effects and for fluctuations due to changes in sample size, orientation, or instrumental parameters. SDA requires only 200 s per sample with inductively coupled plasma optical emission spectrometry (ICP OES). Neither the preparation of a series of standard solutions nor the construction of a universal calibration graph is required. The analysis is performed by combining two solutions in a single container: the first containing 50% sample and 50% standard mixture; the second containing 50% sample and 50% solvent. Data are collected in real time as the first solution is diluted by the second one. The results are used to prepare a plot of the analyte-to-internal standard signal ratio on the y-axis versus the inverse of the internal standard concentration on the x-axis. The analyte concentration in the sample is determined from the ratio of the slope and intercept of that plot. The method has been applied to the determination of FD&C dye Blue No. 1 in mouthwash by molecular absorption spectrometry and to the determination of eight metals in mouthwash, wine, cola, nitric acid, and water by ICP OES. Both the accuracy and precision for SDA are better than those observed for the external calibration, standard additions, and internal standard methods using ICP OES.

  17. Simultaneous determination of 19 triazine pesticides and degradation products in processed cereal samples from Chinese total diet study by isotope dilution-high performance liquid chromatography-linear ion trap mass spectrometry.

    Science.gov (United States)

    Li, Peng; Yang, Xin; Miao, Hong; Zhao, Yunfeng; Liu, Wei; Wu, Yongning

    2013-06-05

    A selective and sensitive isotope dilution-high performance liquid chromatography-linear ion trap mass spectrometry (Isotope Dilution-HPLC-LIT-MS(3)) method was developed for the simultaneous determination of 19 triazine pesticides and their degradation products in processed cereal samples from Chinese total diet study (TDS). The method integrated the addition of isotope internal standards, liquid-liquid extraction (LLE), clean-up with MCX solid-phase extraction (SPE) cartridges and HPLC-LIT-MS(3) analysis with selected reaction monitoring (SRM) mode. Matrix-matched calibration curves showed good linearity (R(2)≥0.9940) verified by applying the Mandel's fitting test (p>0.087) performed at the 95% confidence level. Decision limits (CCαs) and detection capabilities (CCβs) of the 19 triazine pesticides and their degradation products fell in the ranges of 0.0020-0.4200 μg kg(-1) and 0.0024-0.4500 μg kg(-1), respectively. Recoveries ranged from 70.1% to 112.8%, with the relative standard deviations (RSDs) ranging from 1.5% to 13.5%. Furthermore, the proposed method was applied to analyzing the proposed cereal samples from the fourth Chinese TDS. Eleven triazines were detected in six cereal samples with the concentrations ranging from 0.013 to 0.987 μg kg(-1). This method can also be used for the further determination of the triazines in other food group composites, and ultimately served as a methodological foundation for assessing the triazines in the average Chinese diet in the general population. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. A 233U/236U/242Pu/244Pu spike for isotopic and isotope dilution analysis by mass spectrometry with internal calibration

    International Nuclear Information System (INIS)

    Stepanov, A.; Belyaev, B.; Buljanitsa, L.

    1989-11-01

    The Khlopin Radium Institute prepared on behalf of the IAEA a synthetic mixture of 233 U, 236 U, 242 Pu and 244 Pu isotopes. The isotopic composition and elemental concentration of uranium and plutonium were certified on the basis of analyses done by four laboratories of the IAEA Network, using mass spectrometry with internal standardization. The certified values for 233 U/ 236 U ratio and the 236 U chemical concentration have a coefficient of variation of 0.05%. The latter is fixed by the uncertainty in the 235 U/ 238 U ratio of NBS500 used as internal standard. The coefficients of variation of the 244 Pu/ 242 Pu ratio and the 242 Pu chemical concentration are respectively 0.10% and 0.16% and limited by the uncertainty in the 240 Pu/ 239 Pu ratio of NBS947. This four isotope mixture was used as an internal standard as well as a spike, to analyze 30 batches of LWR spent fuel solutions. The repeatability of the mass spectrometric measurements have a coefficient of variation of 0.025% for the uranium concentration, and of 0.039% for the plutonium concentration. The spiking and treatment errors had a coefficient of variation of 0.048%. (author). Refs, figs and tabs

  19. Determination of lead, cadmium, indium, thallium and silver in ancient ices from Antarctica by isotope dilution-thermal ionization mass spectrometry

    Science.gov (United States)

    Matsumoto, A.; Hinkley, T.K.

    1997-01-01

    The concentrations of five chalcophile elements (Pb, Cd, In, Tl and Ag) and the lead isotope rarios in ancient ices from the Taylor Dome near coastal Antarctica, have been determined by the isotope dilutionthermal ionization mass spectrometry (ID-TIMS), with ultra-clean laboratory techniques. The samples were selected from segments of cores, one of which included a visible ash layer. Electric conductivity measurement (ECM) or dielectric properties (DEP) gave distinctive sharp peaks for some of the samples c hosen. Exterior portions of the sample segments were trimmed away by methods described here. Samples w ere evaporated to dryness and later separated into fractions for the five elements using an HBr-HNO3 a nion exchange column method. The concentrations are in the range 2.62-36.7 pg Pb/g of ice, 0.413-2.83 pg Cd/g, 0.081-0.34 pg In/g, 0.096-2.8 pg Tl/g and 0.15-0.84 pg Ag/g. respectively. The dispersions in duplicate analyses are about ??1% for lead and cadmium, ??2% for indium. ??4% for thallium and ??6% for silver, respectively. The concentrations of lead obtained are commonly higher than those in the present-day Antarctic surface snows, but the isotope ratios are distinctively higher than those of the present-day snows and close to those of the other ancient ice collected from a different Antarctic area.

  20. The determination of carbon dioxide concentration using atmospheric pressure ionization mass spectrometry/isotopic dilution and errors in concentration measurements caused by dryers.

    Science.gov (United States)

    DeLacy, Brendan G; Bandy, Alan R

    2008-01-01

    An atmospheric pressure ionization mass spectrometry/isotopically labeled standard (APIMS/ILS) method has been developed for the determination of carbon dioxide (CO(2)) concentration. Descriptions of the instrumental components, the ionization chemistry, and the statistics associated with the analytical method are provided. This method represents an alternative to the nondispersive infrared (NDIR) technique, which is currently used in the atmospheric community to determine atmospheric CO(2) concentrations. The APIMS/ILS and NDIR methods exhibit a decreased sensitivity for CO(2) in the presence of water vapor. Therefore, dryers such as a nafion dryer are used to remove water before detection. The APIMS/ILS method measures mixing ratios and demonstrates linearity and range in the presence or absence of a dryer. The NDIR technique, on the other hand, measures molar concentrations. The second half of this paper describes errors in molar concentration measurements that are caused by drying. An equation describing the errors was derived from the ideal gas law, the conservation of mass, and Dalton's Law. The purpose of this derivation was to quantify errors in the NDIR technique that are caused by drying. Laboratory experiments were conducted to verify the errors created solely by the dryer in CO(2) concentration measurements post-dryer. The laboratory experiments verified the theoretically predicted errors in the derived equations. There are numerous references in the literature that describe the use of a dryer in conjunction with the NDIR technique. However, these references do not address the errors that are caused by drying.

  1. Accumulation of intact sulfur mustard in adipose tissue and toxicokinetics by chemical conversion and isotope-dilution liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Xu, Bin; Zong, Cheng; Zhang, Yajiao; Zhang, Tianhong; Wang, Xiaoying; Qi, Meiling; Wu, Jianfeng; Guo, Lei; Wang, Peng; Chen, Jia; Liu, Qin; Xu, Hua; Xie, Jianwei; Zhang, Zhenqing

    2017-02-01

    Sulfur mustard (SM) is a powerful vesicant and one of the most harmful chemical warfare agents. Although having been studied for a long time, it is still difficult to fully elucidate the mechanisms of SM poisoning, and there is no effective antidote or specific treatment for SM injury. The investigations on toxicokinetics and tissue distribution of SM will help to understand its toxicity and provide a theoretical basis for pretreatment and therapy of SM poisoning. But the metabolic trajectory or fate of intact SM in vivo remains unclear, and there are insufficient experimental data to elucidate, due to its high reactivity and difficulty in biomedical sample analysis. In this paper, a sensitive method for the detection and quantification of intact SM in blood or tissues using isotope-dilution LC-MS/MS coupled with chemical conversion was developed. By transforming highly reactive SM into stable derivative product, the real concentration of intact SM in biological samples was obtained accurately. The toxicokinetics and tissue distribution studies of intact SM in rats were successfully profiled by the novel method after intravenous (10 mg/kg) or cutaneous administration (1, 3 and 10 mg/kg). The SM level in blood with peak time at 30-60 min determined in cutaneous exposure experiment was found much higher than previously reported, and the mean residence time in blood extended to 1-1.5 h. A significant accumulation of intact SM was observed in adipose tissues, including the perirenal fat, epididymal fat, subcutaneous fat and brown fat, in which the concentrations of SM were at least 15 times greater than those in non-adipose tissues in cutaneous exposed rats. The recovery of SM in body fat was calculated as 3.3 % of bioavailable SM (the bioavailability after cutaneous exposure was evaluated as 16 %). Thus, the adipose tissue was important for SM distribution and toxicity, which may pioneer a new model for both the prevention and treatment of SM exposure.

  2. High-throughput screening for various classes of doping agents using a new 'dilute-and-shoot' liquid chromatography-tandem mass spectrometry multi-target approach.

    Science.gov (United States)

    Guddat, S; Solymos, E; Orlovius, A; Thomas, A; Sigmund, G; Geyer, H; Thevis, M; Schänzer, W

    2011-01-01

    A new multi-target approach based on liquid chromatography--electrospray ionization tandem mass spectrometry (LC-(ESI)-MS/MS) is presented to screen for various classes of prohibited substances using direct injection of urine specimens. With a highly sensitive new generation hybrid mass spectrometer classic groups of drugs--for example, diuretics, beta2-agonists--stimulants and narcotics are detectable at concentration levels far below the required limits. Additionally, more challenging and various new target compounds could be implemented. Model compounds of stimulant conjugates were studied to investigate a possible screening without complex sample preparation. As a main achievement, the integration of the plasma volume expanders dextran and hydroxyethyl starch (HES), commonly analyzed in time-consuming, stand-alone procedures, is accomplished. To screen for relatively new prohibited compounds, a common metabolite of the selective androgen receptor modulator (SARMs) andarine, a metabolite of growth hormone releasing peptide (GHRP-2), and 5-amino-4-imidazolecarboxyamide ribonucleoside (AICAR) are analyzed. Following a completely new approach, conjugates of di(2-ethylhexyl) phthalate (DEHP) metabolites are monitored to detect abnormally high levels of plasticizers indicating for illicit blood transfusion. The assay was fully validated for qualitative purposes considering the parameters specificity, intra- (3.2-16.6%) and inter-day precision (0.4-19.9%) at low, medium and high concentration, robustness, limit of detection (1-70 ng/ml, dextran: 30 µg/ml, HES: 10 µg/ml) and ion suppression/enhancement effects. The analyses of post-administration and routine doping control samples demonstrates the applicability of the method for sports drug testing. This straightforward and reliable approach accomplishes the combination of different screening procedures resulting in a high-throughput method that increases the efficiency of the labs daily work. Copyright © 2011 John

  3. Localization of an O-glycosylated site in the recombinant barley alpha-amylase 1 produced in yeast and correction of the amino acid sequence using matrix-assisted laser desorption/ionization mass spectrometry of peptide mixtures

    DEFF Research Database (Denmark)

    Andersen, Jens S.; Søgaard, M; Svensson, B

    1994-01-01

    Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of peptide mixtures was used to characterize recombinant barley alpha-amylase 1, produced in yeast. Three peptide mixtures were generated by cleavage with CNBr, digestion with endoproteinase Lys-C and Asp-N, respectively...

  4. Determination of low-level (sub-microgram) sulfur concentrations by isotope dilution multi-collector inductively couple plasma mass spectrometry using a 33S spike and internal normalization for mass bias correction.

    Science.gov (United States)

    Mann, Jacqueline L; Vocke, Robert D; Kelly, W Robert

    2012-05-30

    The certification of sulfur (S) in Standard Reference Materials™ by the National Institute of Standards and Technology (NIST) has been exclusively performed using isotope dilution thermal ionization mass spectrometry (ID-TIMS). The ID-TIMS measurement method is limited in its capability for low concentration measurements (biofuels made from soy and nanomedicine, pose a challenge to the ID-TIMS technique because of their very low concentrations (gravimetric determination, deviating less than 0.35% and suggesting the technique can yield unbiased and accurate results. The blanks averaged 13 ± 0.0017 ng S (1s). The data results provide a clear indication that the ID-MC-ICP-MS method for the determination of low-level S concentrations is feasible. The more than one order of magnitude reduction of the blanks suggests that it is a better alternative to the ID-TIMS method for very low S materials such as are encountered in biofuels and some biochemical species. Published 2012. This article is a US Government work and is in the public domain in the USA. Published 2012. This article is a US Government work and is in the public domain in the USA.

  5. Characterization of the occupational exposure and air transported particles using the techniques of PIXE 252Cf PMDS and alpha spectrometry

    International Nuclear Information System (INIS)

    Carneiro, Luana Gomes

    2008-01-01

    The risk for human health due to exposure to aerosols depends on the intake pattern, the mass concentration and the speciation of the elements present in airborne particles. In this work PDMS (Plasma Desorption Mass Spectrometry) was used as complementary technique to the PIXE (Particle Induced X ray Emission) technique to characterize aerosols samples collected in the environment. The PIXE technique allows the identification of the elements present in the sample and to determine their mass concentrations. The mass spectrometry (PDMS) was used to identify the speciation of these elements present in the samples. The aerosol samples were collected using a six stage cascade impactor in three sites. The Mass Median Aerodynamic Diameter (MMAD) measured indicated that the airborne particulate were in the fine fraction of the aerosols. The theoretical uranium concentration in urine samples using ICRP lung model parameters suggest that the elemental mass concentration in respirable fraction of aerosol and the chemical speciation are important factors to determine the uranium concentration in urine and that the determination of specific solubility parameters for each compound is the most important factor to calculate the uranium concentration in urine. PIXE allows to identify and quantify the elements heavier than Na (Z=11) while PDMS allows to identify the organic and inorganic compounds present in the samples. As these techniques are used as complementary techniques they provide important information about the aerosols characterization. (author)

  6. AN EXPERIMENTAL INVESTIGATION OF THE 236U DETECTION LIMIT IN THE SURFACE AIR USING RADIOCHEMICAL SEPARATION AND ALPHA-SPECTROMETRY

    Directory of Open Access Journals (Sweden)

    A. D. Gedeonov

    2011-01-01

    Full Text Available Due to nuclear weapon testing, nuclear reactor accidents, uranium mining and nuclear fuel reprocessing, additional uranium has been introduced into the environment. 236U isotope is produced from 235U by capture of a thermal neutron and it can be used as an indicator for artificial uranium in the environment. In this paper the sensitive method for236U determination in the surface air is described. This method includes a total dissolution of the air dust in a mixture of mineral acids, uranium concentration and purification by anion-exchange chromatography. Long time measurements of the separated uranium fraction are made with the use of alpha-spectrometer based on PIPS-detector. The lower limit of detection for 236U in the surface air is determined as 5 • 10-9 Bq/m3 (2 ng/m3.

  7. Application of isotopic dillution techniques by alpha and mass spechometry for determining uranium and evaluated its distributIon in geological materials

    International Nuclear Information System (INIS)

    Shihomatsu, H.M.

    1987-01-01

    Determination of uranium in the concentration range of 2 to 4000 ppm in nuclear raw materials by mass spectrometric (MSID) and alpha spectrometric isotope dilution techniques (ASID), using the isotope tracer enriched in 233 U, is presented. An investigation on the nature of the thermoionic emission in various types of filament arrangements like, single plane rhenium, single boat and double, are carried out for the isotope analysis by mass spectrometry. In the preparation of the sources for alpha spectrometry by electrodeposition the experimental parameters such as: current density, pH of the mixed solution containing sample and electrolyte, concentration of the electrolyte solution, time of deposition and distance between electrodes are optimised. The accuracy of the technique is discussed based on the determination of uranium in the same samples by other research workers employing various analytical techniques including mass spectrometric and alpha spectrometric isotope dilution techniques (MSID and ASID). (author) [pt

  8. Analysis of plutonium isotope ratios including238Pu/239Pu in individual U-Pu mixed oxide particles by means of a combination of alpha spectrometry and ICP-MS.

    Science.gov (United States)

    Esaka, Fumitaka; Yasuda, Kenichiro; Suzuki, Daisuke; Miyamoto, Yutaka; Magara, Masaaki

    2017-04-01

    Isotope ratio analysis of individual uranium-plutonium (U-Pu) mixed oxide particles contained within environmental samples taken from nuclear facilities is proving to be increasingly important in the field of nuclear safeguards. However, isobaric interferences, such as 238 U with 238 Pu and 241 Am with 241 Pu, make it difficult to determine plutonium isotope ratios in mass spectrometric measurements. In the present study, the isotope ratios of 238 Pu/ 239 Pu, 240 Pu/ 239 Pu, 241 Pu/ 239 Pu, and 242 Pu/ 239 Pu were measured for individual Pu and U-Pu mixed oxide particles by a combination of alpha spectrometry and inductively coupled plasma mass spectrometry (ICP-MS). As a consequence, we were able to determine the 240 Pu/ 239 Pu, 241 Pu/ 239 Pu, and 242 Pu/ 239 Pu isotope ratios with ICP-MS after particle dissolution and chemical separation of plutonium with UTEVA resins. Furthermore, 238 Pu/ 239 Pu isotope ratios were able to be calculated by using both the 238 Pu/( 239 Pu+ 240 Pu) activity ratios that had been measured through alpha spectrometry and the 240 Pu/ 239 Pu isotope ratios determined through ICP-MS. Therefore, the combined use of alpha spectrometry and ICP-MS is useful in determining plutonium isotope ratios, including 238 Pu/ 239 Pu, in individual U-Pu mixed oxide particles. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Simultaneous determinations of uranium, thorium, and plutonium in soft tissues by solvent extraction and alpha-spectrometry

    International Nuclear Information System (INIS)

    Singh, N.P.; Zimmerman, C.J.; Lewis, L.L.; Wrenn, M.E.

    1984-01-01

    A radiochemical procedure for the simultaneous determination of uranium, thorium, and plutonium, in soft tissues has been developed. The weighed amounts of tissues, spiked with 232 U, 242 Pu, and 229 th tracers, are wet ashed. Uranium, thorium, and plutonium are coprecipitated with iron as hydroxides, dissolved in concentrated HCl and the acidity adjusted to 10 M. Uranium and plutonium are extracted into 20% TLA solution in xylene, leaving thorium in the aqueous phase. Plutonium is back-extracted by reducing to the trivalent state with 0.05 M NH 4 I solution in 8 M HCl, and uranium is back-extracted with 0.1 M HCl. Thorium is extracted into 20% TLA solution from 4 M HNO 3 and back-extracted with 10 M HCl. Uranium, thorium and plutonium are electrodeposited separately onto platinum discs and counted alpha-spectrometrically using surface barrier silicon diodes and a multichannel analyzer. The method was developed using bovine liver and applied to dog and human tissues. The mean radiochemical recoveries of these actinides in different organs were better than 70%. 6 references, 2 tables

  10. Development of a methodology for the detection of Ra226 in large volumes of water by gamma spectrometry; modification and validation of the method for detection and quantification of Ra226 in small volumes of water by alpha spectrometry, used by the Centro de Investigacion en Ciencias Atomicas, Nucleares y Moleculares (CICANUM, UCR)

    International Nuclear Information System (INIS)

    Molina Porras, Arnold

    2011-01-01

    The test method has been validated for quantifying the specific activity of Ra 226 in water alpha spectrometry. The CICANUM has used this method as part of the proposed harmonization of methods ARCAL (IAEA). The method is based on a first separation and preconcentration of Ra 226 by coprecipitation and subsequent MnO 2 micro precipitation as Ba (Ra) SO 4 . Samples were prepared and then was performed the counting by alpha spectrometry. A methodology of radio sampling for large volumes of water was tested in parallel, using acrylic fibers impregnated with manganese oxide (IV) to determine the amount of Ra 226 present by gamma spectrometry. Small-scale tests, have determined that the best way to prepare the fiber is the reference method found in the literature and using the oven at 60 degrees Celsius. (author) [es

  11. Magnetic immunoassay coupled with inductively coupled plasma mass spectrometry for simultaneous quantification of alpha-fetoprotein and carcinoembryonic antigen in human serum

    Science.gov (United States)

    Zhang, Xing; Chen, Beibei; He, Man; Zhang, Yiwen; Xiao, Guangyang; Hu, Bin

    2015-04-01

    The absolute quantification of glycoproteins in complex biological samples is a challenge and of great significance. Herein, 4-mercaptophenylboronic acid functionalized magnetic beads were prepared to selectively capture glycoproteins, while antibody conjugated gold and silver nanoparticles were synthesized as element tags to label two different glycoproteins. Based on that, a new approach of magnetic immunoassay-inductively coupled plasma mass spectrometry (ICP-MS) was established for simultaneous quantitative analysis of glycoproteins. Taking biomarkers of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) as two model glycoproteins, experimental parameters involved in the immunoassay procedure were carefully optimized and analytical performance of the proposed method was evaluated. The limits of detection (LODs) for AFP and CEA were 0.086 μg L- 1 and 0.054 μg L- 1 with the relative standard deviations (RSDs, n = 7, c = 5 μg L- 1) of 6.5% and 6.2% for AFP and CEA, respectively. Linear range for both AFP and CEA was 0.2-50 μg L- 1. To validate the applicability of the proposed method, human serum samples were analyzed, and the obtained results were in good agreement with that obtained by the clinical chemiluminescence immunoassay. The developed method exhibited good selectivity and sensitivity for the simultaneous determination of AFP and CEA, and extended the applicability of metal nanoparticle tags based on ICP-MS methodology in multiple glycoprotein quantifications.

  12. In Situ Peroxidase Labeling and Mass-Spectrometry Connects Alpha-Synuclein Directly to Endocytic Trafficking and mRNA Metabolism in Neurons.

    Science.gov (United States)

    Chung, Chee Yeun; Khurana, Vikram; Yi, Song; Sahni, Nidhi; Loh, Ken H; Auluck, Pavan K; Baru, Valeriya; Udeshi, Namrata D; Freyzon, Yelena; Carr, Steven A; Hill, David E; Vidal, Marc; Ting, Alice Y; Lindquist, Susan

    2017-02-22

    Synucleinopathies, including Parkinson's disease (PD), are associated with the misfolding and mistrafficking of alpha-synuclein (α-syn). Here, using an ascorbate peroxidase (APEX)-based labeling method combined with mass spectrometry, we defined a network of proteins in the immediate vicinity of α-syn in living neurons to shed light on α-syn function. This approach identified 225 proteins, including synaptic proteins, proteins involved in endocytic vesicle trafficking, the retromer complex, phosphatases and mRNA binding proteins. Many were in complexes with α-syn, and some were encoded by genes known to be risk factors for PD and other neurodegenerative diseases. Endocytic trafficking and mRNA translation proteins within this spatial α-syn map overlapped with genetic modifiers of α-syn toxicity, developed in an accompanying study (Khurana et al., this issue of Cell Systems). Our data suggest that perturbation of these particular pathways is directly related to the spatial localization of α-syn within the cell. These approaches provide new avenues to systematically examine protein function and pathology in living cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Determination of As and Se in crude oil diluted in xylene by inductively coupled plasma mass spectrometry using a dynamic reaction cell for interference correction on {sup 80}Se

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Fernanda Inda de [Departamento de Quimica, Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rua Marques de Sao Vicente 225, 22451-900 Rio de Janeiro, RJ (Brazil); Duyck, Christiane B., E-mail: cbduyck@vm.uff.br [Departamento de Quimica, Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rua Marques de Sao Vicente 225, 22451-900 Rio de Janeiro, RJ (Brazil); Departamento de Quimica, Universidade Federal Fluminense (UFF), Outeiro Sao Joao Batista s/n, Centro, 24020-150, Niteroi, RJ (Brazil); Fonseca, Teresa Cristina O. [Centro de Pesquisas Leopoldo A. Miguez de Mello da Petrobras (CENPES) (Brazil); Saint' Pierre, Tatiana D. [Departamento de Quimica, Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rua Marques de Sao Vicente 225, 22451-900 Rio de Janeiro, RJ (Brazil)

    2012-05-15

    Arsenic and selenium can be found in crude oils and represent an important source of pollution when released to the environment during any stage of extraction or refinery. These elements present low sensitivity in the direct determination by inductively coupled plasma mass spectrometry (ICP-MS), due to their high ionization potential, and are also prone to spectral interferences. Hydride generation (HG) can be alternatively employed for the separation of these analytes from the sample matrix and introduction into the instrument. However, the required sample preparation usually increases the analysis time. In this work, a method was developed for the determination of As and Se in crude oil by ICP-MS, after sample dilution in xylene. The use of a dynamic reaction cell (DRC) allowed for the overcoming of Ar{sub 2}{sup +} interference on {sup 80}Se, but was not necessary for As, since interference on m/z 75 was not observed. The optimized operational conditions for {sup 75}As and {sup 80}Se were: 1350 W of RF power, 0.4 L min{sup -1} of Ar nebulizer and 0.7 L min{sup -1} of Ar auxiliary flow rates. The DRC conditions for {sup 80}Se were 0.5 L min{sup -1} of methane and rejection parameter q (Rpq) of 0.2. The analyses were carried out by analyte addition and the limits of detection (LOD) were 0.04 {mu}g kg{sup -1} for As and 0.1 {mu}g kg{sup -1} for Se. The accuracy was verified by the analysis of residual fuel oil certified material, with agreement at a 95% confidence level. Nine Brazilian crude oil samples were analyzed and the results compared to those obtained by hydride generation ICP-MS. In this case, samples were decomposed with nitric acid in a digester block, the analytes pre-reduced with HCl 6 mol L{sup -1} and the determination carried out by external calibration. Although better instrumental LODs were obtained by HG (0.002 {mu}g kg{sup -1} of As and 0.04 {mu}g kg{sup -1} of Se), the direct determination of As and Se in crude oil diluted in xylene by DRC

  14. Comprehensive profiling of mercapturic acid metabolites from dietary acrylamide as short-term exposure biomarkers for evaluation of toxicokinetics in rats and daily internal exposure in humans using isotope dilution ultra-high performance liquid chromatography tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yu [Department of Food Science and Nutrition, College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, Zhejiang (China); Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, Zhejiang (China); Wang, Qiao; Cheng, Jun [Department of Food Science and Nutrition, College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, Zhejiang (China); Zhang, Jingshun; Xu, Jiaojiao [Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, Zhejiang (China); Ren, Yiping, E-mail: renyiping@263.net [Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, Zhejiang (China)

    2015-09-24

    Mercapturic acid metabolites from dietary acrylamide are important short-term exposure biomarkers for evaluating the in vivo toxicity of acrylamide. Most of studies have focused on the measurement of two metabolites, N-acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA) and N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine (GAMA). Thus, the comprehensive profile of acrylamide urinary metabolites cannot be fully understood. We developed an isotope dilution ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for the simultaneous determination of all four mercapturic acid adducts of acrylamide and its primary metabolite glycidamide under the electroscopy ionization negative (ESI-) mode in the present study. The limit of detection (LOD) and limit of quantification (LOQ) of the analytes ranged 0.1–0.3 ng/mL and 0.4–1.0 ng/mL, respectively. The recovery rates with low, intermediate and high spiking levels were calculated as 95.5%–105.4%, 98.2%–114.0% and 92.2%–108.9%, respectively. Acceptable within-laboratory reproducibility (RSD < 7.0%) substantially supported the use of current method for robust analysis. Rapid pretreatment procedures and short run time (8 min per sample) ensured good efficiency of metabolism profiling, indicating a wide application for investigating short-term internal exposure of dietary acrylamide. Our proposed UHPLC-MS/MS method was successfully applied to the toxicokinetic study of acrylamide in rats. Meanwhile, results of human urine analysis indicated that the levels of N-acetyl-S-(2-carbamoylethyl)-L-cysteine-sulfoxide (AAMA-sul), which did not appear in the mercapturic acid metabolites in rodents, were more than the sum of GAMA and N-acetyl-S-(1-carbamoyl-2-hydroxyethyl)-L-cysteine (iso-GAMA). Thus, AAMA-sul may alternatively become a specific biomarker for investigating the acrylamide exposure in humans. Current proposed method provides a substantial methodology support for comprehensive

  15. Comprehensive profiling of mercapturic acid metabolites from dietary acrylamide as short-term exposure biomarkers for evaluation of toxicokinetics in rats and daily internal exposure in humans using isotope dilution ultra-high performance liquid chromatography tandem mass spectrometry

    International Nuclear Information System (INIS)

    Zhang, Yu; Wang, Qiao; Cheng, Jun; Zhang, Jingshun; Xu, Jiaojiao; Ren, Yiping

    2015-01-01

    Mercapturic acid metabolites from dietary acrylamide are important short-term exposure biomarkers for evaluating the in vivo toxicity of acrylamide. Most of studies have focused on the measurement of two metabolites, N-acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA) and N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine (GAMA). Thus, the comprehensive profile of acrylamide urinary metabolites cannot be fully understood. We developed an isotope dilution ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for the simultaneous determination of all four mercapturic acid adducts of acrylamide and its primary metabolite glycidamide under the electroscopy ionization negative (ESI-) mode in the present study. The limit of detection (LOD) and limit of quantification (LOQ) of the analytes ranged 0.1–0.3 ng/mL and 0.4–1.0 ng/mL, respectively. The recovery rates with low, intermediate and high spiking levels were calculated as 95.5%–105.4%, 98.2%–114.0% and 92.2%–108.9%, respectively. Acceptable within-laboratory reproducibility (RSD < 7.0%) substantially supported the use of current method for robust analysis. Rapid pretreatment procedures and short run time (8 min per sample) ensured good efficiency of metabolism profiling, indicating a wide application for investigating short-term internal exposure of dietary acrylamide. Our proposed UHPLC-MS/MS method was successfully applied to the toxicokinetic study of acrylamide in rats. Meanwhile, results of human urine analysis indicated that the levels of N-acetyl-S-(2-carbamoylethyl)-L-cysteine-sulfoxide (AAMA-sul), which did not appear in the mercapturic acid metabolites in rodents, were more than the sum of GAMA and N-acetyl-S-(1-carbamoyl-2-hydroxyethyl)-L-cysteine (iso-GAMA). Thus, AAMA-sul may alternatively become a specific biomarker for investigating the acrylamide exposure in humans. Current proposed method provides a substantial methodology support for comprehensive

  16. Abundance of four sulfur mustard-DNA adducts ex vivo and in vivo revealed by simultaneous quantification in stable isotope dilution-ultrahigh performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Yue, Lijun; Wei, Yuxia; Chen, Jia; Shi, Huiqin; Liu, Qin; Zhang, Yajiao; He, Jun; Guo, Lei; Zhang, Tingfen; Xie, Jianwei; Peng, Shuangqing

    2014-04-21

    Sulfur mustard (SM) is a highly reactive alkylating vesicant and causes blisters upon contact with skin, eyes, and respiratory organs. It covalently links with DNAs by forming four mono- or cross-link adducts. In this article, the reference standards of SM-DNA adducts and deuterated analogues were first synthesized with simplified procedures containing only one or two steps and using less toxic chemical 2-(2-chloroethylthio)ethanol or nontoxic chemical thiodiglycol as starting materials. A sensitive and high-throughput simultaneous quantification method of N(7)-[2-[(2-hydroxyethyl)thio]-ethyl]guanine (N(7)-HETEG), O(6)-[2-[(2-hydroxyethyl)thio]-ethyl]guanine (O(6)-HETEG), N(3)-[2-[(2-hydroxyethyl)thio]-ethyl]adenine (N(3)-HETEA), and bis[2-(guanin-7-yl)ethyl]sulfide (Bis-G) in the Sprague-Dawley rat derma samples was developed by stable isotope dilution-ultrahigh performance liquid chromatography-tandem mass spectrometry (ID-UPLC-MS/MS) with the aim of revealing the real metabolic behaviors of four adducts. The method was validated, the limit of detection (S/N ratio greater than 10) was 0.01, 0.002, 0.04, and 0.11 fmol on column for N(7)-HETEG, O(6)-HETEG, Bis-G, and N(3)-HETEA, respectively, and the lower limit of quantification (S/N ratio greater than 20) was 0.04, 0.01, 0.12, and 0.33 fmol on column for N(7)-HETEG, O(6)-HETEG, Bis-G, and N(3)-HETEA, respectively. The accuracy of this method was determined to be 76% to 129% (n = 3), and both the interday (n = 6) and intraday (n = 7) precisions were less than 10%. The method was further applied for the quantifications of four adducts in the derma of adult male Sprague-Dawley rats exposed to SM ex vivo and in vivo, and all adducts had time- and dose-effect relationships. To the best of our knowledge, this is the first time that the real presented status of four DNA adducts was simultaneously revealed by the MS-based method, in which Bis-G showed much higher abundance than the result previously reported and N(3

  17. Magnetic immunoassay coupled with inductively coupled plasma mass spectrometry for simultaneous quantification of alpha-fetoprotein and carcinoembryonic antigen in human serum

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xing; Chen, Beibei; He, Man; Zhang, Yiwen; Xiao, Guangyang; Hu, Bin, E-mail: binhu@whu.edu.cn

    2015-04-01

    The absolute quantification of glycoproteins in complex biological samples is a challenge and of great significance. Herein, 4-mercaptophenylboronic acid functionalized magnetic beads were prepared to selectively capture glycoproteins, while antibody conjugated gold and silver nanoparticles were synthesized as element tags to label two different glycoproteins. Based on that, a new approach of magnetic immunoassay-inductively coupled plasma mass spectrometry (ICP-MS) was established for simultaneous quantitative analysis of glycoproteins. Taking biomarkers of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) as two model glycoproteins, experimental parameters involved in the immunoassay procedure were carefully optimized and analytical performance of the proposed method was evaluated. The limits of detection (LODs) for AFP and CEA were 0.086 μg L{sup −1} and 0.054 μg L{sup −1} with the relative standard deviations (RSDs, n = 7, c = 5 μg L{sup −1}) of 6.5% and 6.2% for AFP and CEA, respectively. Linear range for both AFP and CEA was 0.2–50 μg L{sup −1}. To validate the applicability of the proposed method, human serum samples were analyzed, and the obtained results were in good agreement with that obtained by the clinical chemiluminescence immunoassay. The developed method exhibited good selectivity and sensitivity for the simultaneous determination of AFP and CEA, and extended the applicability of metal nanoparticle tags based on ICP-MS methodology in multiple glycoprotein quantifications. - Highlights: • 4-Mercaptophenylboronic acid functionalized magnetic beads were prepared and characterized. • ICP-MS based magnetic immunoassay approach was developed for quantification of glycoproteins. • AFP and CEA were quantified simultaneously with Au and Ag NPs as element tags. • The developed method exhibited good selectivity and sensitivity for target glycoproteins.

  18. Description of analytical method and clinical utility of measuring serum 7-alpha-hydroxy-4-cholesten-3-one (7aC4) by mass spectrometry.

    Science.gov (United States)

    Donato, Leslie J; Lueke, Alan; Kenyon, Stacy M; Meeusen, Jeffrey W; Camilleri, Michael

    2018-02-01

    Imbalance of bile acids (BA) homeostasis in the gastrointestinal tract can lead to chronic diarrhea or constipation when BA in the colon are in excess or low, respectively. Since both disturbances of bowel function can result from other etiologies, identifying BA imbalance is important to tailor treatment strategies. Serum concentrations of 7-alpha-hydroxy-4-cholesten-3-one (7aC4), a precursor in bile acid synthesis, reflect BA homeostasis. Here we describe a method to accurately measure serum 7aC4 and evaluate the clinical utility in patients with diarrhea or constipation phenotypes. Serum 7aC4 is measured after acetonitrile protein precipitation using C18 liquid chromatography, tandem mass spectrometry, and deuterium-labeled 7aC4 internal standard. Assay performance including linearity, precision, and accuracy was assessed using waste serum samples. The reference interval was established in healthy individuals without BA-altering conditions or medications. Clinical performance was assessed in patients with irritable bowel syndrome. The method precisely and accurately measured 7aC4 in human serum from 1.4-338ng/mL with no ion suppression or interference from related 7-keto-cholesterol. Central 95th percentile reference interval was 2.5-63.2ng/mL. Lower serum 7aC4 was found in patients with constipation with sensitivity/specificity of 79%/55% compared to healthy controls. Higher 7aC4 was found in patients with bile acid diarrhea (BAD) compared to those without BAD with sensitivity/specificity of 82%/53%. We have developed a sensitive and precise assay for measuring the concentration of 7aC4 in serum. The assay can be used to screen for diarrhea caused by bile acid malabsorption. Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  19. Plutonium determination by isotope dilution

    International Nuclear Information System (INIS)

    Lucas, M.

    1980-01-01

    The principle is to add to a known amount of the analysed solution a known amount of a spike solution consisting of plutonium 242. The isotopic composition of the resulting mixture is then determined by surface ionization mass spectrometry, and the plutonium concentration in the solution is deduced, from this measurement. For irradiated fuels neutronic studies or for fissile materials balance measurements, requiring the knowledge of the ratio U/Pu or of concentration both uranium and plutonium, it is better to use the double spike isotope dilution method, with a spike solution of known 233 U- 242 Pu ratio. Using this method, the ratio of uranium to plutonium concentration in the irradiated fuel solution can be determined without any accurate measurement of the mixed amounts of sample and spike solutions. For fissile material balance measurements, the uranium concentration is determined by using single isotope dilution, and the plutonium concentration is deduced from the ratio Pu/U and U concentration. The main advantages of isotope dilution are its selectivity, accuracy and very high sensitivity. The recent improvements made to surface ionization mass spectrometers have considerably increased the precision of the measurements; a relative precision of about 0.2% to 0.3% is obtained currently, but it could be reduced to 0.1%, in the future, with a careful control of the experimental procedures. The detection limite is around 0.1 ppb [fr

  20. Microfluidic serial dilution ladder.

    Science.gov (United States)

    Ahrar, Siavash; Hwang, Michelle; Duncan, Philip N; Hui, Elliot E

    2014-01-07

    Serial dilution is a fundamental procedure that is common to a large number of laboratory protocols. Automation of serial dilution is thus a valuable component for lab-on-a-chip systems. While a handful of different microfluidic strategies for serial dilution have been reported, approaches based on continuous flow mixing inherently consume larger amounts of sample volume and chip real estate. We employ valve-driven circulatory mixing to address these issues and also introduce a novel device structure to store each stage of the dilution process. The dilution strategy is based on sequentially mixing the rungs of a ladder structure. We demonstrate a 7-stage series of 1 : 1 dilutions with R(2) equal to 0.995 in an active device area of 1 cm(2).

  1. Comparison between hydride generation and nebulization for sample introduction in the determination of lead in plants and water samples by inductively coupled plasma mass spectrometry, using external calibration and isotope dilution

    International Nuclear Information System (INIS)

    Petrov, Panayot K.; Wibetoe, Grethe; Tsalev, Dimiter L.

    2006-01-01

    Four inductively coupled plasma mass spectrometric methods: nebulization sample introduction with external calibration; hydride generation with external calibration; isotope dilution with nebulization; and isotope dilution with hydride generation, have been tested and compared. Multimode Sample Introduction System (MSIS TM ) was employed in either nebulization or hydride generation mode. Best limits of detection (below 0.1 μg L -1 ) and accuracy were obtained for isotope dilution techniques in hydride generation and sample nebulization mode. A mixture of HNO 3 and H 2 O 2 served both for microwave-assisted digestion as well as a medium for subsequent plumbane generation. Optimal reagent concentrations for hydride generation stage were 0.1 mol L -1 HNO 3 , 0.28 mol L -1 H 2 O 2 and 1.5% m/v NaBH 4 . Critical effects of acidity, blanks and concomitants have been discussed. Analytical methods were validated by use of plant and water certified reference materials and spiked high-salt solutions (seawater and 20% m/v NaCl) at lead levels in nanograms per gram to micrograms per gram range

  2. Radioisotope dilution analyses of geological samples using 236U and 229Th

    International Nuclear Information System (INIS)

    Rosholt, J.N.

    1984-01-01

    The use of 236 U and 229 Th in alpha spectrometric measurements has some advantages over the use of other tracers and measurement techniques in isotope dilution analyses of most geological samples. The advantages are: 1) these isotopes do not occur in terrestrial rocks, 2) they have negligible decay losses because of their long half lives, 3) they cause minimal recoil contamination to surface-barrier detectors, 4) they allow for simultaneous determination of the concentration and isotopic composition of uranium and thorium in a variety of sample types, and 5) they allow for simple and constant corrections for spectral interferences, 0.5% of the 238 U activity is subtracted for the contribution of 235 U in the 236 U peak and 1% of the 229 Th activity is subtracted from the 230 Th activity. Disadvantages in using 236 U and 229 Th are: 1) individual separates of uranium and thorium must be prepared as very thin sources for alpha spectrometry, 2) good resolution in the spectrometer system is required for thorium isotopic measurements where measurement times may extend to 300 h, and 3) separate calibrations of the 236 U and 229 Th spike solution with both uranium and thorium standards are required. The use of these tracers in applications of uranium-series disequilibrium studies has simplified the measurements required for the determination of the isotopic composition of uranium and thorium because of the minimal corrections needed for alpha spectral interferences. (orig.)

  3. A sequential method for the determination of 210Pb, 226Ra, and uranium and thorium radioisotopes by LSC and alpha-spectrometry.

    Science.gov (United States)

    Lozano, J C; Tomé, F Vera; Rodríguez, P Blanco; Prieto, C

    2010-01-01

    A procedure for the determination of (210)Pb, and alpha-emitting radioisotopes of uranium, thorium, and radium from the same aliquot of a sample has been proposed. The key step consisted in the recovery of Pb(II) and Ra by precipitation of insoluble Pb(NO(3))(2), the uranium and thorium radioisotopes remaining in solution. Afterwards, the fractions were handled by specific, well consolidated procedures. Lead-210 was determined by the LSC technique while the uranium, thorium, and radium radioisotopes were measured with silicon alpha-spectrometers. The procedure was applied to a reference sample and several environmental samples obtaining satisfactory results. Copyright 2009 Elsevier Ltd. All rights reserved.

  4. Hybridizing pines with diluted pollen

    Science.gov (United States)

    Robert Z. Callaham

    1967-01-01

    Diluted pollens would have many uses by the tree breeder. Dilutions would be particularly advantageous in making many controlled pollinations with a limited amount of pollen. They also would be useful in artificial mass pollinations of orchards or single trees. Diluted pollens might help overcome troublesome genetic barriers to crossing. Feasibility o,f using diluted...

  5. Helium dilution refrigeration system

    Science.gov (United States)

    Roach, P.R.; Gray, K.E.

    1988-09-13

    A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation is disclosed. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains [sup 3]He and [sup 4]He liquids which are precooled by a coupled container containing [sup 3]He liquid, enabling the phase separation of a [sup 3]He rich liquid phase from a dilute [sup 3]He-[sup 4]He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the [sup 3]He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute [sup 3]He-[sup 4]He liquid phase. 2 figs.

  6. Boron concentration measurements by alpha spectrometry and quantitative neutron autoradiography in cells and tissues treated with different boronated formulations and administration protocols.

    Science.gov (United States)

    Bortolussi, Silva; Ciani, Laura; Postuma, Ian; Protti, Nicoletta; Luca Reversi; Bruschi, Piero; Ferrari, Cinzia; Cansolino, Laura; Panza, Luigi; Ristori, Sandra; Altieri, Saverio

    2014-06-01

    The possibility to measure boron concentration with high precision in tissues that will be irradiated represents a fundamental step for a safe and effective BNCT treatment. In Pavia, two techniques have been used for this purpose, a quantitative method based on charged particles spectrometry and a boron biodistribution imaging based on neutron autoradiography. A quantitative method to determine boron concentration by neutron autoradiography has been recently set-up and calibrated for the measurement of biological samples, both solid and liquid, in the frame of the feasibility study of BNCT. This technique was calibrated and the obtained results were cross checked with those of α spectrometry, in order to validate them. The comparisons were performed using tissues taken form animals treated with different boron administration protocols. Subsequently the quantitative neutron autoradiography was employed to measure osteosarcoma cell samples treated with BPA and with new boronated formulations. © 2013 Published by Elsevier Ltd.

  7. Micro-electrodeposition techniques for the preparation of small actinide counting sources for ultra-high resolution alpha spectrometry by microcalorimetry

    International Nuclear Information System (INIS)

    Plionis, A.A.; Hastings, E.P.; LaMont, S.P.; Dry, D.E.; Bacrania, M.K.; Rabin, M.W.; Rim, J.H.

    2009-01-01

    Special considerations and techniques are desired for the preparation of small actinide counting sources. Counting sources have been prepared on metal disk substrates (planchets) with an active area of only 0.079 mm 2 . This represents a 93.75% reduction in deposition area from standard electrodeposition methods. The actinide distribution upon the smaller planchet must remain thin and uniform to allow alpha particle emissions to escape the counting source with a minimal amount of self-attenuation. This work describes the development of micro-electrodeposition methods and optimization of the technique with respect to deposition time and current density for various planchet sizes. (author)

  8. Procedure for the determination of uranium on cellulose air-sampling filters by photon-electron-rejecting-alpha-liquid-scintillation spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    McDowell, W.J.; Case, G.N.

    1986-08-01

    A procedure is described for obtaining from cellulose air-sampling filters the total uranium content whether it be in the form of metal, oxide, tetrafluoride or most other salts of uranium. It is demonstrated that the uranium content can be accurately assayed by low-temperature ashing of the filter paper, dissolving the ash in a mixed nitrate-sulfate system, extracting the uranium selectively into a scintillator containing a high-molecular-weight amine sulfate, and counting the extract using a Photon-Electron-Rejecting-Alpha-Liquid-Scintillation (PERALS) spectrometer. 2 refs., 4 figs., 2 tabs.

  9. Mass spectrometry in clinical chemistry

    International Nuclear Information System (INIS)

    Pettersen, J.E.

    1977-01-01

    A brief description is given of the functional elements of a mass spectrometer and of some currently employed mass spectrometric techniques, such as combined gas chromatography-mass spectrometry, mass chromatography, and selected ion monitoring. Various areas of application of mass spectrometry in clinical chemistry are discussed, such as inborn errors of metabolism and other metabolic disorders, intoxications, quantitative determinations of drugs, hormones, gases, and trace elements, and the use of isotope dilution mass spectrometry as a definitive method for the establishment of true values for concentrations of various compounds in reference sera. It is concluded that mass spectrometry is of great value in clinical chemistry. (Auth.)

  10. Determination of zearalenone and its metabolites alpha- and beta-zearalenol in beer samples by high-performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Zöllner, P; Berner, D; Jodlbauer, J; Lindner, W

    2000-02-11

    A fast, robust and sensitive LC-MS-MS method for the determination of zearalenone (ZON) and its metabolites alpha-zearalenol (alpha-ZOL) and beta-zearalenol (beta-ZOL) in beer samples is described. Sample preparation was performed by direct RP-18 solid-phase extraction of undiluted beer samples followed by selective determination of analytes by LC-MS-MS applying an atmospheric pressure chemical ionization (APCI) interface. Using the negative ion mode limits of determination of 0.03-0.06 microg l(-1) beer and limits of quantification of 0.07-0.15 microg l(-1) beer were achieved, which was distinctly more sensitive than in the positive ion mode. Twenty-three beer samples from different countries, produced from different grains and under different brewing conditions, were investigated by this method, but only in one sample could beta-ZOL and ZON be detected. Independently of the type of beer, relative standard deviations between 2.1% and 3.3%, a linear working range of 0.15 microg l(-1) to 500 microg l(-1) beer and recovery rates around 100% could be achieved when zearalanone (ZAN) was used as internal standard.

  11. A Procedure for the Sequential Determination of Radionuclides in Phosphogypsum Liquid Scintillation Counting and Alpha Spectrometry for 210Po, 210Pb, 226Ra, Th and U Radioisotopes

    International Nuclear Information System (INIS)

    2014-01-01

    Since 2004, the Environment Programme of the IAEA has included activities aimed at the development of a set of procedures for the determination of radionuclides in terrestrial environmental samples. Reliable, comparable and 'fit for purpose' results are essential requirements for any decision based on analytical measurements. For the analyst, tested and validated analytical procedures are extremely important tools for the production of such analytical data. For maximum utility, such procedures should be comprehensive, clearly formulated, and readily available to both the analyst and the customer for reference. In this publication, a combined procedure for the sequential determination of 210Po, 210Pb, 226Ra, Th and U radioisotopes in phosphogypsum is described. The method is based on the dissolution of small amounts of phosphogypsum by microwave digestion, followed by sequential separation of 210Po, 210Pb, Th and U radioisotopes by selective extraction chromatography using Sr, TEVA and UTEVA resins. Radium-226 is separated from interfering elements using Ba(Ra)SO4 co-precipitation. Lead-210 is determined by liquid scintillation counting. The alpha source of 210Po is prepared by autodeposition on a silver plate. The alpha sources of Th and U are prepared by electrodeposition on a stainless steel plate. A comprehensive methodology for the calculation of results, including the quantification of measurement uncertainty, was also developed. The procedure is introduced as a recommended procedure and validated in terms of trueness, repeatability and reproducibility in accordance with ISO guidelines

  12. A Collaborative Study: Determination of Mycotoxins in Corn, Peanut Butter, and Wheat Flour Using Stable Isotope Dilution Assay (SIDA) and Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS).

    Science.gov (United States)

    Zhang, Kai; Schaab, Matthew R; Southwood, Gavin; Tor, Elizabeth R; Aston, Linda S; Song, Wenlu; Eitzer, Brian; Majumdar, Sanghamitra; Lapainis, Theodore; Mai, Huy; Tran, Kevin; El-Demerdash, Aref; Vega, Victor; Cai, Yanxuan; Wong, Jon W; Krynitsky, Alexandra J; Begley, Timothy H

    2017-08-23

    A collaborative study was conducted to evaluate stable isotope dilution assay (SIDA) and LC-MS/MS for the simultaneous determination of aflatoxins B 1 , B 2 , G 1 , and G 2 ; deoxynivalenol; fumonisins B 1 , B 2 , and B 3 ; ochratoxin A; HT-2 toxin; T-2 toxin; and zearalenone in foods. Samples were fortified with 12 13 C uniformly labeled mycotoxins ( 13 C-IS) corresponding to the native mycotoxins and extracted with acetonitrile/water (50:50 v/v), followed by centrifugation, filtration, and LC-MS/MS analysis. In addition to certified reference materials, the six participating laboratories analyzed corn, peanut butter, and wheat flour fortified with the 12 mycotoxins at concentrations ranging from 1.0 to 1000 ng/g. Using their available LC-MS/MS platform, each laboratory developed in-house instrumental conditions for analysis. The majority of recoveries ranged from 80 to 120% with relative standard derivations (RSDs) <20%. Greater than 90% of the average recoveries of the participating laboratories were in the range of 90-110%, with repeatability RSD r (within laboratory) < 10% and reproducibility RSD R (among laboratory) < 15%. All Z scores of the results of certified reference materials were between -2 and 2. Using 13 C-IS eliminated the need for matrix-matched calibration standards for quantitation, simplified sample preparation, and achieved simultaneous identification and quantitation of multiple mycotoxins in a simple LC-MS/MS procedure.

  13. Quantification of transformation rates of soil amino sugars and amino acids by a novel isotope pool dilution approach via liquid chromatography/high resolution mass spectrometry (LC/HRMS)

    Science.gov (United States)

    Hu, Yuntao; Zheng, Qing; Noll, Lisa; Zhang, Shasha; Wanek, Wolfgang

    2017-04-01

    Organic nitrogen transformation processes are the key driver of soil nitrogen availability, strongly affecting the nitrogen turnover and carbon cycling of terrestrial ecosystems. Low molecular weight organic nitrogen compounds (e.g. amino acids and amino sugars) that can be directly utilized by plants or microorganisms are released by the extracellular cleavage of high molecular weight organic nitrogen compounds (e.g. proteins, peptidoglycan, and chitin) by hydrolytic enzymes. This decomposition process is believed to be the rate-limiting step in the soil N cycle. Direct measurements of the in situ transformation rates of these small N compounds is highly challenging but can be realized by applying the isotope pool dilution (IPD) technique, in which the target compound pool is labeled with isotopic tracers and subsequently the dilution of the tracers is measured. We have recently pioneered the development of IPD assays to investigate the in situ flux of proteinaceous amino acids and glucose due to decomposition of organic matter and microbial utilization, but the roles of fluxes of amino sugars and amino acid enantiomers in soil nitrogen transformation processes are still unknown due to the lack of feasible extraction, purification, separation and detection methods. Here we developed a 15N IPD assay by utilizing a novel LC/HRMS (Orbitrap) platform, with the aim to measure transformation rates of amino sugars and amino acid enantiomers. After the tracer experiments soil extracts were purified by solid phase extraction prior to the analysis by MS. The utilization of Orbitrap-HRMS allowed us to resolve the mass signals of unlabeled analytes, and their 15N labeled (tracers) and 13C labeled (internal standards) analogues. The commercially unavailable 15N and 13C labeled amino sugars and amino acid enantiomers were produced from bacterial cell walls after batch culture in labeled growth media. This workflow was validated with soils from two sampling sites, allowing us to

  14. Simultaneous determination of seven β2-agonists in human and bovine urine by isotope dilution liquid chromatography-tandem mass spectrometry using compound-specific minimally 13C-labelled analogues.

    Science.gov (United States)

    González-Antuña, Ana; Rodríguez-González, Pablo; Centineo, Giuseppe; García Alonso, J Ignacio

    2014-10-29

    Seven β 2 -agonist (clenproperol, clenbuterol, salbutamol, bronbuterol, ractopamine, clenpenterol and clencyclohexerol) were determined simultaneously in human and bovine urine by isotope dilution LC-ESI-MS/MS in a triple quadrupole instrument. The method is based on the application of multiple linear regression in combination with compound-specific minimally 13 C-labelled analogues. Additionally, the increase of the bandpass of the first quadrupole during the selected reaction monitoring (SRM) measurement procedure allowed the simultaneous quantification of the seven compounds at sub ngg -1 levels in a single chromatogram without resorting to a methodological calibration graph. Recovery values at concentration levels between 5.0 and 0.05ngg -1 ranged from 95 to 110% in fortified bovine urine and from 91 to 108% in human urine, with relative standard deviations lower than 5% except for salbutamol and ractopamine. The proposed methodology was validated by analyzing the certified reference material BCR-503 (lyophilized bovine urine) certified for clenbuterol and salbutamol. The limits of detection (LOD) for a sample volume of 10mL of both human and bovine urine was found to be lower than 0.012ngg -1 for all compounds, except to salbutamol in bovine urine which was of 0.029ngg -1 . The use of compound-specific isotopically labelled analogues minimally labelled in 13 C minimized the occurrence of isotope effects and corrected for matrix effects during ESI ionization and can be efficiently applied for the quantification of ultra-trace concentrations of β 2 -agonists in human and bovine urine. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Identification of Clinical Streptococcus pneumoniae Isolates among other Alpha and Nonhemolytic Streptococci by Use of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System

    Science.gov (United States)

    Segonds, Christine; Prere, Marie-Françoise; Marty, Nicole; Oswald, Eric

    2013-01-01

    Discrimination between Streptococcus pneumoniae and its close relatives of the viridans group is a common difficulty in matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry-based identification. In the present study, the performances of the Vitek MS MALDI-TOF mass spectrometry system were assessed using 334 pneumococci, 166 other S. mitis group streptococci, 184 non-S. mitis group streptococci, and 19 related alpha- and nonhemolytic aerobic Gram-positive catalase-negative coccal isolates. Pneumococci had been identified by means of optochin susceptibility and bile solubility or serotyping, and other isolates mainly by use of RapidID32 Strep strips. In case of discordant or low-discrimination results, genotypic methods were used. The sensitivity of the Vitek MS for the identification of S. pneumoniae was 99.1%, since only three bile-insoluble isolates were misidentified as Streptococcus mitis/Streptococcus oralis. Conversely, two optochin-resistant pneumococci were correctly identified (specificity, 100%). Three Streptococcus pseudopneumoniae isolates were also correctly identified. Among nonpneumococcal isolates, 90.8% (n = 335) were correctly identified to the species or subspecies level and 2.4% (n = 9) at the group level. For the remaining 25 isolates, the Vitek MS proposed a bacterial species included in the list of possible species suggested by genotypic methods, except for 4 isolates which were not identified due to the absence of the species in the database. According to our study, the Vitek MS displays performance similar to that of the optochin susceptibility test for routine identification of pneumococcal isolates. Moreover, the Vitek MS is efficient for the identification of other viridans group streptococci and related isolates, provided that the species are included in the database. PMID:23576536

  16. Analysis of urinary 8-isoprostane as an oxidative stress biomarker by stable isotope dilution using automated online in-tube solid-phase microextraction coupled with liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Mizuno, Keisuke; Kataoka, Hiroyuki

    2015-08-10

    We have developed a simple and sensitive method for the determination of the oxidative stress biomarker 8-isoprostane (8-IP) in human urine by automated online in-tube solid-phase microextraction (SPME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) using a Zorbax Eclipse XDB-8 column and 0.1% formic acid/methanol (25/75, v/v) as a mobile phase. Electrospray MS/MS for 8-IP was performed on an API 4000 triple quadruple mass spectrometer in negative ion mode. The optimum in-tube SPME conditions were 20 draw/eject cycles with a sample size of 40 μL using a Carboxen 1006 PLOT capillary column for the extraction. The extracted compounds were easily desorbed from the capillary by passage of the mobile phase, and no carryover was observed. Total analysis time of this method including online extraction and analysis was about 30 min for each sample. The in-tube SPME LC-MS/MS method showed good linearity in the concentration range of 20-1000 pg/mL with a correlation coefficient r = 0.9999 for 8-IP using a stable isotope-labeled internal standard, 8-IP-d4. The detection limit of 8-IP was 3.3 pg/mL and the proposed method showed 42-fold higher sensitivity than the direct injection method. The intra-day and inter-day precisions (relative standard deviations) were below 5.0% and 8.5% (n = 5), respectively. This method was applied successfully to the analysis of urine samples without pretreatment or interference peaks. The recovery rates of 8-IP spiked into urine samples were above 92%. This method is useful for assessing the effects of oxidative stress and antioxidant intake. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Determination of acrylamide in Chinese traditional carbohydrate-rich foods using gas chromatography with micro-electron capture detector and isotope dilution liquid chromatography combined with electrospray ionization tandem mass spectrometry

    International Nuclear Information System (INIS)

    Zhang Yu; Ren Yiping; Zhao Hangmei; Zhang Ying

    2007-01-01

    The present study developed two analytical methods for quantification of acrylamide in complex food matrixes, such as Chinese traditional carbohydrate-rich foods. One is based on derivatization with potassium bromate and potassium bromide without clean-up prior to gas chromatography with micro-electron capture detector (GC-MECD). Alternatively, the underivatized acrylamide was detected by high-performance liquid chromatography coupled to quadrupole tandem mass spectrometry (HPLC-MS/MS) in the positive electrospray ionization mode. For both methods, the Chinese carbohydrate-rich samples were homogenized, defatted with petroleum ether and extracted with aqueous solution of sodium chloride. Recovery rates for acrylamide from spiked Chinese style foods with the spiking level of 50, 500 and 1000 μg kg -1 were in the range of 79-93% for the GC-MECD including derivatization and 84-97% for the HPLC-MS/MS method. Typical quantification limits of the HPLC-MSMS method were 4 μg kg -1 for acrylamide. The GC-MECD method achieved quantification limits of 10 μg kg -1 in Chinese style foods. Thirty-eight Chinese traditional foods purchased from different manufacturers were analyzed and compared with four Western style foods. Acrylamide contaminant was found in all of samples at the concentration up to 771.1 and 734.5 μg kg -1 detected by the GC and HPLC method, respectively. The concentrations determined with the two different quantitative methods corresponded well with each other. A convenient and fast pretreatment procedure will be optimized in order to satisfy further investigation of hundreds of samples

  18. A Procedure for the Sequential Determination of Radionuclides in Environmental Samples. Liquid Scintillation Counting and Alpha Spectrometry for 90Sr, 241Am and Pu Radioisotopes

    International Nuclear Information System (INIS)

    2014-01-01

    Since 2004, IAEA activities related to the terrestrial environment have aimed at the development of a set of procedures to determine radionuclides in environmental samples. Reliable, comparable and ‘fit for purpose’ results are an essential requirement for any decision based on analytical measurements. For the analyst, tested and validated analytical procedures are extremely important tools for the production of analytical data. For maximum utility, such procedures should be comprehensive, clearly formulated and readily available for reference to both the analyst and the customer. This publication describes a combined procedure for the sequential determination of 90 Sr, 241 Am and Pu radioisotopes in environmental samples. The method is based on the chemical separation of strontium, americium and plutonium using ion exchange chromatography, extraction chromatography and precipitation followed by alpha spectrometric and liquid scintillation counting detection. The method was tested and validated in terms of repeatability and trueness in accordance with International Organization for Standardization (ISO) guidelines using reference materials and proficiency test samples. Reproducibility tests were performed later at the IAEA Terrestrial Environment Laboratory. The calculations of the massic activity, uncertainty budget, decision threshold and detection limit are also described in this publication. The procedure is introduced for the determination of 90 Sr, 241 Am and Pu radioisotopes in environmental samples such as soil, sediment, air filter and vegetation samples. It is expected to be of general use to a wide range of laboratories, including the Analytical Laboratories for the Measurement of Environmental Radioactivity (ALMERA) network for routine environmental monitoring purposes

  19. Double spike methodology for uranium determination by thermal ionisation mass spectrometry: separation and purification of 234U

    International Nuclear Information System (INIS)

    Shah, P.M.; Saxena, M.K.; Sanjai Kumar; Aggarwal, S.K.; Jain, H.C.

    1995-01-01

    With an objective to prepare double spike of 233 U+ 234 U for determination of uranium concentration by Isotopic Dilution Thermal Ionisation Mass Spectrometry (ID-TIMS), 234 U was separated and purified from aged 238 Pu sample (15 years old) using several ion exchange and solvent extraction procedures. Final product containing 95% and 5% alpha activities of 234 and 238 Pu, respectively, which translates into 99.998 atom% of 234 U and 0.002 atom% of 238 Pu was found suitable for double spike. (author). 1 ref

  20. A field survey of metal binding to metallothionein and other cytosolic ligands in liver of eels using an on-line isotope dilution method in combination with size exclusion (SE) high pressure liquid chromatography (HPLC) coupled to Inductively Coupled Plasma time-of-flight Mass Spectrometry (ICP-TOFMS).

    Science.gov (United States)

    Van Campenhout, Karen; Goenaga Infante, Heidi; Goemans, Geert; Belpaire, Claude; Adams, Freddy; Blust, Ronny; Bervoets, Lieven

    2008-05-15

    The effect of metal exposure on the accumulation and cytosolic speciation of metals in livers of wild populations of European eel with special emphasis on metallothioneins (MT) was studied. Four sampling sites in Flanders showing different degrees of heavy metal contamination were selected for this purpose. An on-line isotope dilution method in combination with size exclusion (SE) high pressure liquid chromatography (HPLC) coupled to Inductively Coupled Plasma time-of-flight Mass Spectrometry (ICP-TOFMS) was used to study the cytosolic speciation of the metals. The distribution of the metals Cd, Cu, Ni, Pb and Zn among cytosolic fractions displayed strong differences. The cytosolic concentration of Cd, Ni and Pb increased proportionally with the total liver levels. However, the cytosolic concentrations of Cu and Zn only increased above a certain liver tissue threshold level. Cd, Cu and Zn, but not Pb and Ni, were largely associated with the MT pool in correspondence with the environmental exposure and liver tissue concentrations. Most of the Pb and Ni and a considerable fraction of Cu and Zn, but not Cd, were associated to High Molecular Weight (HMW) fractions. The relative importance of the Cu and Zn in the HMW fraction decreased with increasing contamination levels while the MT pool became progressively more important. The close relationship between the cytosolic metal load and the total MT levels or the metals bound on the MT pool indicates that the metals, rather than other stress factors, are the major factor determining MT induction.

  1. Evaluation of uncertainty and detection limits in 210Pb and 210Po measurement in water by alpha spectrometry using 210Po spontaneous deposition onto a silver disk

    International Nuclear Information System (INIS)

    Fernández, Pedro L.; Gómez, José; Ródenas, Carmen

    2012-01-01

    An easy and accurate method for the determination of 210 Pb and 210 Po in water using 210 Po spontaneous deposition onto a silver disk is proposed and assessed for its detection capabilities according to the ISO Guide for the expression of uncertainty in measurement (GUM) and ISO Standard 11929-7 concerning the evaluation of the characteristic limits for ionizing radiation measurements. The method makes no assumption on the initial values of the activity concentrations of 210 Pb, 210 Bi and 210 Po in the sample to be analyzed, and is based on the alpha spectrometric measurement of 210 Po in two different aliquots: the first one measured five weeks after the sampling date to ensure radioactive equilibrium between 210 Pb and 210 Bi and the second after a sufficient time for the ingrowth of 210 Po from 210 Pb to be significant. As shown, for a recommended time interval of seven months between 210 Po measurements, the applicability of the proposed method is limited to water samples with a 226 Ra to 210 Pb activity ratio C Ra /C Pb ≤4, as usual in natural waters. Using sample and background counting times of 24 h and 240 h, respectively, the detection limit of the activity concentration of each radionuclide at the sampling time for a 1 L sample typically varies between 0.7 and 16 mBq L −1 for 210 Pb in water samples with an initial activity of 210 Po in the range 0–200 mBq L −1 , and between 0.6 and 8.5 mBq L −1 for 210 Po in water samples with an initial activity of 210 Pb in the same range. - Highlights: ► 210 Pb and 210 Po measurement in water by 210 Po spontaneous deposition onto silver disks. ► 210 Pb and 210 Po determination based on 210 Po measurement in two different aliquots. ► Evaluation of characteristic limits in radioactivity measurements using ISO 11929-7. ► 10 Pb - 210 Po detection limits decrease with time elapsed between 210 Po measurements.

  2. Contribution to the study of the {alpha} spectrometry by the impulse ionization chamber. Application to the study of the beam fine structure of some heavy nuclei; Contribution a l'etude de la spectrometrie {alpha} par la chambre d'ionisation a impulsion. Application a l'etude de la structure fine du rayonnement de quelques noyaux lourds

    Energy Technology Data Exchange (ETDEWEB)

    Valladas, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1954-05-15

    In the first part, it studies an impulse spectrometer of which the resolution and stability have been pushed to their maximum possibilities. It uses an ionization chamber because of its simple and steady functioning. The general characteristics and building of the ionization chamber are described. The electronic devices are described as well as the recording system. The theoretical study of the amplifier has allowed to reduce the amplitude dispersion from electronic devices as background noise. The resolution in energy of an {alpha} spectrometer using an impulse ionization chamber is studied and results are discussed. The spectral lines display of the fine structure under the effect of conversion electrons emitted by coincidence in the ionization chamber is studied. Finally, the detection possibilities of very low intensity spectral lines of fine structure of detection are considered. In the second part, the {alpha} emission of fine structure of {sup 230}Th, {sup 234}U and {sup 238}U nuclei is studied. (M.P.)

  3. Alpha sources deposit by sublimation

    International Nuclear Information System (INIS)

    Amoudry, F.; Eloy, J.F.

    1983-09-01

    We studied and realized a device able to perform some very thin substracts used for alpha spectrometry measurements. Sources are prepared by sublimation of the sample in a vacuum container. The energy required for this sublimation is furnished by a laser beam [fr

  4. Rapid quantification of alpha emitters in low- and intermediate-level dry radioactive waste

    International Nuclear Information System (INIS)

    Tae-Hong Park; Eul-Hye Jeon; Yong Sul Choi; Jong-Ho Park; Hong Joo Ahn; Yong Jun Park

    2016-01-01

    We developed a rapid quantification method of Pu, Am, and Cm in low- and intermediate-level radioactive waste using TRU resin, alpha spectrometry, and thermal ionization mass spectrometry for radioactive waste disposal. In particular, we focused on the optimization of sample preparation methods for alpha spectrometry and mass spectrometry to reduce the analysis time. The optimized method used Am and Pu stripping solutions for micro-coprecipitation and showed good recovery and alpha spectrum resolution for alpha counting. In addition, appropriate selection of Pu elution solution decreased the sample preparation time for thermal ionization mass spectrometry measurements. (author)

  5. Validation of a nanoliquid chromatography-tandem mass spectrometry method for the identification and the accurate quantification by isotopic dilution of glutathionylated and cysteinylated precursors of 3-mercaptohexan-1-ol and 4-mercapto-4-methylpentan-2-one in white grape juices.

    Science.gov (United States)

    Roland, Aurélie; Vialaret, Jérôme; Moniatte, Marc; Rigou, Peggy; Razungles, Alain; Schneider, Rémi

    2010-03-05

    A rapid nanoLC-MS/MS method was developed and validated for the simultaneous determination of glutathionylated and cysteinylated precursors of 3-mercapto-hexan-1-ol (3MH) and 4-methyl-4-mercaptopentan-2-one in grape juice using stable isotope dilution assay (SIDA). The analytes were extracted from must using a cation exchange resin and purified on C18 cartridges. They were chromatographically separated on a reverse phase column and finally analyzed by tandem mass spectrometry in selected reaction monitoring mode (SRM) using deuterated analogues as standards except for glutathionylated conjugate of 4MMP which was analyzed by external calibration. The method was validated according to the International Conference on Harmonization recommendations by determining linearity, accuracy, precision, recovery, matrix effect, repeatability, intermediate reproducibility, LODs and LOQs. Calibration for each precursor was determined by performing Lack-of-Fit test and the best fitting for 3MH precursors was a quadratic model whereas a linear model was better adapted for 4MMP precursors. All calibration curves showed quite satisfactory correlation coefficients (R(2)>0.995 for SIDA quantification and R(2)>0.985 for external calibration). Quantification by SIDA and external calibration allowed a high level of accuracy since the averaged value ranged from 80 to 108%. Quantification of aroma precursors was accurate and reproducible over five days since intermediate precision (same analyst, same sample and same apparatus), which was evaluated by the calculation of RSD was inferior to 16%. Limits of quantification for G3MH and G4MMP were closed to 0.50 and 0.07 nmol/L and as 4.75 and 1.90 nmol/L for Cys3MH and Cys4MMP respectively. This method was applied to the quantification of precursors into several types of grape juices: Melon B., Sauvignon, Riesling and Gewurztraminer. 2010 Elsevier B.V. All rights reserved.

  6. Single-run determination of polybrominated diphenyl ethers (PBDEs) di- to deca-brominated in fish meal, fish oil and fish feed by isotope dilution: Application of automated sample purification and gas chromatography/ion trap tandem mass spectrometry (GC/ITMS)

    International Nuclear Information System (INIS)

    Blanco, Sonia Lucia; Vieites, Juan M.

    2010-01-01

    The present paper describes the application of automated cleanup and fractionation procedures of the Power Prep system (Fluid Management Systems) for the determination of polybrominated diphenyl ethers (PBDEs) in feeding stuffs and fish meal and oil. Gas chromatography (GC) separation followed by ion trap tandem mass spectrometry detection in EI mode (ITMS) allowed the analysis of di- to deca-BDEs in the samples matrices used in fish aquaculture. The method developed enabled the determination of 26 native PBDE congeners and 11 13 C 12 -labelled congeners, including deca-BDE 209, in a single-run analysis, using isotope dilution. The automated cleanup, consisting of a succession of multilayer silica and basic alumina columns previously applied by Wyrzykowska et al. (2009) in combustion flue gas, was succesfully applied in our complex matrices. The method allowed an increase in productivity, i.e. lower time was required to process samples, and simultaneous purification of several samples was achieved at a time, reducing analyst dedication and human error input. Average recoveries of 43-96% were obtained. GC/ITMS can overcome the complexity originating from the sample matrix, eliminating matrix effects by tandem MS, to enable the detection of congeners penta- to nona-BDEs where interferent masses were present. The provisional detection limits, estimated in the samples, were 5-30 pg for di-, tri-, tetra-, and penta-BDEs, 20-65 pg for hexa-, hepta-, octa- and nona-BDEs, and 105 pg for deca-BDE. Reduction of deca-BDE 209 blank values is of concern to ongoing research. Good accuracy was obtained by application of the whole procedure, representing an efficient, low-cost and fast alternative for routine analyses.

  7. Quantitation of Nine Lactones in Dairy Cream by Stable Isotope Dilution Assays Based on Novel Syntheses of Carbon-13-Labeled γ-Lactones and Deuterium-Labeled δ-Lactones in Combination with Comprehensive Two-Dimensional Gas Chromatography with Time-of-Flight Mass Spectrometry.

    Science.gov (United States)

    Schütt, Jessica; Schieberle, Peter

    2017-12-06

    Lactones are well-known aroma compounds in, e.g., fruits and fermented foods as well as in dairy products, such as cream or milk powders. The latter are often used in confectionary products, e.g., milk chocolate. Lactones are suggested to contribute to the distinct aroma of dairy products and have also been reported in milk chocolate. However, data on their contribution to the overall aroma of this type of chocolate are scarce. As a result of their pH-dependent instability and their low volatility, a reliable quantitation of lactones is a challenge. Thus, to allow for a quantitation of nine lactones in one single comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry in electron ionization mode run, new synthetic routes were developed for five carbon-13-labeled γ-lactones and four deuterium-labeled δ-lactones, with the isotope label in the ring to be used in stable isotope dilution assays. The concentrations of the nine lactones were then analyzed in raw and pasteurized cream as well as in a heat-treated raw cream. δ-Dodecalactone and δ-decalactone showed the highest concentrations in both the raw and pasteurized cream. In the latter, δ-dodecalactone reached a 2.5-fold higher concentration compared to the raw cream. Subsequent heat treatments in a lab scale showed a further increase by factors of 13 and 19, respectively, suggesting a high potential of lactone precursors in cream. The results serve as a basis for further studies on lactone formation in other thermally processed products, such as milk chocolate.

  8. Improved peak shape fitting in alpha spectra.

    Science.gov (United States)

    Pommé, S; Caro Marroyo, B

    2015-02-01

    Peak overlap is a recurrent issue in alpha-particle spectrometry, not only in routine analyses but also in the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae are presented for the deconvolution of alpha-particle spectra. They have been implemented as fit functions in a spreadsheet application and optimum fit parameters were searched with built-in optimisation routines. Deconvolution results are shown for a few challenging spectra with high statistical precision. The algorithm outperforms the best available routines for high-resolution spectrometry, which may facilitate a more reliable determination of alpha emission probabilities in the future. It is also applicable to alpha spectra with inferior energy resolution. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  9. Determination of natural alpha-emitting isotopes of uranium and thorium in environmental and geological samples

    International Nuclear Information System (INIS)

    Crespo, M.T.

    1996-01-01

    It is described the complete radiochemical procedure used for the determination of uranium and thorium isotopes in environmental and geological samples by alpha spectrometry. Source preparation methods, alpha-counting and spectral analysis are also included

  10. Prevention of uncontrolled boron dilution

    International Nuclear Information System (INIS)

    Sere, J. L.

    1997-01-01

    The paper presents a synthesis of the global analysis of uncontrolled boron dilution risk performed by (European Consortium Mochovce (EUCOM) in the frame of Safety Measures RC 01 and AA 11. Recommendation for additional improvements (mainly I and C interlocks or inhibition) are presented. (author)

  11. Buffett's Alpha

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Kabiller, David; Heje Pedersen, Lasse

    Berkshire Hathaway has realized a Sharpe ratio of 0.76, higher than any other stock or mutual fund with a history of more than 30 years, and Berkshire has a significant alpha to traditional risk factors. However, we find that the alpha becomes insignificant when controlling for exposures to Betting-Against-Beta...... in publicly traded stocks versus wholly-owned private companies, we find that the former performs the best, suggesting that Buffett's returns are more due to stock selection than to his effect on management. These results have broad implications for market efficiency and the implementability of academic...

  12. Alpha particles detection in nitrocellulose

    International Nuclear Information System (INIS)

    Romero C, M.

    1976-01-01

    The method for the manufacturing of the detection films follows these steps: preparation of the mass which includes nitrocellulose in the form of cotton as raw material ethyl acetate, cellosolve acetate, isopropyl and butyl alcohols as solvents and dioctyl phtalate as plasticiser; dilution of the paste; pouring of the diluted mass; and drying of the detection films. The results obtained experimentally are: The determination of the development times of the different thicknesses of the manufactured films. Response linearity of the detectors, variation of the number of tracks according to the distance of the source to the detector. Sizes of the diameter of the tracks depending of the distance detector-alpha emmission source. As a conclusion we can say the the nitrocellulose detectors are specific for alpha radiation; the more effective thicknesses in uranium prospecting works were those of 60 microns, since for the laboratory works the thicknesses of 30 to 40 microns were the ideal; the development technique of the detection films is simple and cheap and can be realized even in another place than the laboratory; this way of the manufacturing of nitrocellulose detection film sensitive to alpha nuclear radiation is open to future research. (author)

  13. Uranium determination by isotopic dilution

    International Nuclear Information System (INIS)

    Lucas, M.

    1978-01-01

    The method of determination by isotopic dilution is reviewed. The method principle is outlined with emphasis on sample preparation and on tracer solution preparation and calibration. The validity conditions of the method are defined for both high uranium concentrations and trace determination, the detection limit being around 0.1 ppb. The main advantages of the method are its selectivity, very high sensitivity and precision. The main fields of application are nuclear industry, geochronology and isotopic geochemistry [fr

  14. Improved peak shape fitting in alpha spectra

    OpenAIRE

    POMME Stefaan; CARO MARROYO BELEN

    2014-01-01

    Peak overlap is a recurrent issue ina lpha-particle spectrometry, not only in routine analyses but also in the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae are presented for the deconvolution of alpha-particle spectra. They have been implemented as fit functions in a spreadsheet application and optimum fit parameters were searched with built-in optimisation routines. Deconvolution results are shown...

  15. Thermal ionisation mass spectrometry (TIMS): what, how and why?

    International Nuclear Information System (INIS)

    Aggarwal, S.K.

    2002-01-01

    Thermal ionisation mass spectrometry (TIMS) is one of the oldest mass spectrometric techniques, which has been used for determining the isotopic composition and concentration of different elements using isotope dilution. In spite of the introduction of many other inorganic mass spectrometric techniques like spark source mass spectrometry (SSMS), glow discharge mass spectrometry (GDMS), inductively coupled plasma-mass spectrometry (ICP-MS), secondary ion mass spectrometry (SIMS), the TIMS technique plays the role of a definitive analytical methodology and still occupies a unique position in terms of its capabilities with respect to precision and accuracy as well as sensitivity

  16. Forgot your password: Correlation dilution

    OpenAIRE

    Medard, Muriel; Makhdoumi Kakhaki, Ali; Calmon, Flavio du Pin

    2015-01-01

    We consider the problem of diluting common randomness from correlated observations by separated agents. This problem creates a new framework to study statistical privacy, in which a legitimate party, Alice, has access to a random variable X, whereas an attacker, Bob, has access to a random variable Y dependent on X drawn from a joint distribution p[subscript X,Y]. Alice's goal is to produce a non-trivial function of her available information that is uncorrelated with (has small correlation wi...

  17. A miniaturized plastic dilution refrigerator

    International Nuclear Information System (INIS)

    Bindilatti, V.; Oliveira, N.F.Jr.; Martin, R.V.; Frossati, G.

    1996-01-01

    We have built and tested a miniaturized dilution refrigerator, completely contained (still, heat exchanger and mixing chamber) inside a plastic (PVC) tube of 10 mm diameter and 170 mm length. With a 25 cm 2 CuNi heat exchanger, it reached temperatures below 50 mK, for circulation rates below 70 μmol/s. The cooling power at 100 mK and 63 μmol/s was 45 μW. The experimental space could accommodate samples up to 6 mm in diameter. (author)

  18. Spectrometry techniques for radioactivity measurements

    International Nuclear Information System (INIS)

    Anilkumar, S.

    2016-01-01

    The energy of the radiation emission following the nuclear decay is unique and the characteristic of the radio nuclide which undergoes decay. Thus measurement of the energy of the radiation offers a method of identifying the radio nuclides. The prime requirement of the energy measurement is a suitable detector which shows response proportional to the energy of the radiation rather than the presence of the radiation. The response from such detectors are suitably processed and distributed with respect to the signal strength which is proportional to incident energy. This distribution is normally referred as energy spectrum and is recorded in the multichannel analyser. The measurement of energy and intensity of radiation from the spectrum is called radiation spectrometry. Thus the radiation spectrometry allows the identification and quantification of radioactive isotopes in variety of matrices. The radiation spectrometry has now become a popular radioanalytical technique in wide area of nuclear fuel cycle programs. The popular spectrometry techniques commonly used for the radioactivity measurement and analysis are Alpha spectrometry, Gamma ray spectrometry and Beta spectrometry

  19. Measurement of radon daughters in air samples by alpha spectroscopy

    International Nuclear Information System (INIS)

    Acena, M.L.; Crespo, M.T.

    1989-01-01

    The concentration of radon progeny in air has been determined by alpha spectrometry measurement of polonium 214 and polonium 218. A known volume of air was passed through a filter, then the alpha activity was directly measured on this filter (Author)

  20. Numerical analysis of alpha spectra using two different codes

    International Nuclear Information System (INIS)

    Hurtado, S.; Jimenez-Ramos, M.C.; Villa, M.; Vioque, I.; Manjon, G.; Garcia-Tenorio, R.

    2008-01-01

    This work presents an intercomparison between commercial software for alpha-particle spectrometry, Genie 2000, and the new free available software, Winalpha, developed by International Atomic Energy Agency (IAEA). In order to compare both codes, different environmental spectra containing plutonium, uranium, thorium and polonium have been analyzed, together with IAEA test alpha spectra. A statistical study was performed in order to evaluate the precision and accuracy in the analyses, and to enhance the confidence in using the software on alpha spectrometric studies

  1. Desynchronization in diluted neural networks

    International Nuclear Information System (INIS)

    Zillmer, Ruediger; Livi, Roberto; Politi, Antonio; Torcini, Alessandro

    2006-01-01

    The dynamical behavior of a weakly diluted fully inhibitory network of pulse-coupled spiking neurons is investigated. Upon increasing the coupling strength, a transition from regular to stochasticlike regime is observed. In the weak-coupling phase, a periodic dynamics is rapidly approached, with all neurons firing with the same rate and mutually phase locked. The strong-coupling phase is characterized by an irregular pattern, even though the maximum Lyapunov exponent is negative. The paradox is solved by drawing an analogy with the phenomenon of 'stable chaos', i.e., by observing that the stochasticlike behavior is 'limited' to an exponentially long (with the system size) transient. Remarkably, the transient dynamics turns out to be stationary

  2. Elimination of alpha-gal xenoreactive epitope: alpha-galactosidase treatment of porcine heart valves.

    Science.gov (United States)

    Choi, Sun-Young; Jeong, Hee-Jin; Lim, Hong-Gook; Park, Seong-Sik; Kim, Soo-Hwan; Kim, Yong Jin

    2012-05-01

    Porcine heart valves are among the most widely used tissue valves in clinical heart valve implantation. However, immunologic responses have been implicated as potential causes of the limited durability of xenograft heart valves. The study aim was to determine the effectiveness of alpha-galactosidase treatment used to degrade the major xenoreactive antigens found in xenograft heart valves. Fresh porcine heart valves and pericardium treated with alpha-galactosidase were studied to evaluate the xenoreactive galactose (alpha1,3) galactose (alpha-gal) antigen. Removal of the alpha-gal epitope from the porcine heart valve was monitored via 3,3'-diaminobenzidine staining intensity, while the removal of alpha-gal from N-glycans on porcine heart valves treated with recombinant alpha-galactosidase was determined either qualitatively or quantitatively by mass fingerprinting using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The porcine pericardium was used for monitoring the change in mechanical properties after alpha-galactosidase treatment. In addition, the biomechanical modification property of collagen fiber rearrangement on tissue was assessed using transmission electron microscopy (TEM). Following a 24-h incubation at pH 7.2, 4 degrees C, employing 0.1 U/ml of Bacteroides thetaiotaomicron-derived recombinant alpha-galactosidase, the enzyme effectively removed the alpha-gal epitopes expressed on porcine heart valves. The identification type of alpha-gal N-glycan on fresh aortic valve, aortic wall, pulmonary valve, and pulmonary wall was 7.1%, 10.3%, 6% and 8%, respectively. In the presence of alpha-galactosidase treatment, alpha-gal-containing N-glycans were converted into alpha-gal-negative N-glycans. Likewise, alpha-gal-containing N-glycans were not detected when MALDI-TOF MS quantitative analysis was used. Furthermore, no significant difference was observed in the mechanical properties and findings from TEM in alpha

  3. Coulomb correction to elastic. alpha. -. alpha. scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bera, P.K.; Jana, A.K.; Haque, N.; Talukdar, B. (Department of Physics, Visva-Bharati University, Santiniketan-731235, West Bengal, India (IN))

    1991-02-01

    The elastic {alpha}-{alpha} scattering is treated within the framework of a generalized phase-function method (GPFM). This generalization consists in absorbing the effect of Coulomb interaction in the comparison functions for developing the phase equation. Based on values of scattering phase shifts computed by the present method, it is concluded that the GPFM provides an uncomplicated approach to rigorous Coulomb correction in the {alpha}-{alpha} scattering.

  4. Molecular dissociation in dilute gas

    Science.gov (United States)

    Renfrow, S. N.; Duggan, J. L.; McDaniel, F. D.

    1999-06-01

    The charge state distributions (CSD) produced during molecular dissociation are important to both Trace Element Accelerator Mass Spectrometry (TEAMS) and the ion implantation industry. The CSD of 1.3-1.7 MeV SiN+, SiMg+, SiMn+, and SiZn+ molecules have been measured for elements that do not form atomic negative ions (N, Mg, Mn, and Zn) using a NEC Tandem Pelletron accelerator. The molecules were produced in a Cs sputter negative ion source, accelerated, magnetically analyzed, and then passed through an N2 gas cell. The neutral and charged breakups where analyzed using an electrostatic deflector and measured with particle detectors. Equilibrium CSD were determined and comparisons made between molecular and atomic ion data.

  5. Intrahepatic expression of interferon alpha & interferon alpha ...

    African Journals Online (AJOL)

    kemrilib

    Alpha m-RNA while 30% only expressed Interferon Alpha Receptor m-RNA. Responders and non-responders to Interferon therapy ... expression of IFN Alpha Receptor mRNA. Regardless of the response to interferon, histological .... generation reverse hybridisation, line probe assay. (Inno-LiPA HCV II; Innogenetics, Ghent,.

  6. Cost effectiveness of dilute chemical decontamination

    International Nuclear Information System (INIS)

    LeSurf, J.E.; Weyman, G.D.

    The basic principles of dilute chemical decontamination are described, as well as the method of application. Methods of computing savings in radiation dose and costs are presented, with results from actual experience and illustrative examples. It is concluded that dilute chemical decontamination is beneficial in many cases. It reduces radiation exposure of workers, saves money, and simplifies maintenance work

  7. Storm Sewage Dilution in Smaller Streams

    DEFF Research Database (Denmark)

    Larsen, Torben; Vestergaard, Kristian

    1987-01-01

    A numerical model has been used to show how dilution in smaller streams can be effected by unsteady hydraulic conditions caused by a storm sewage overflow.......A numerical model has been used to show how dilution in smaller streams can be effected by unsteady hydraulic conditions caused by a storm sewage overflow....

  8. Mass spectrometry

    DEFF Research Database (Denmark)

    Nyvang Hartmeyer, Gitte; Jensen, Anne Kvistholm; Böcher, Sidsel

    2010-01-01

    Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is currently being introduced for the rapid and accurate identification of bacteria. We describe 2 MALDI-TOF MS identification cases - 1 directly on spinal fluid and 1 on grown bacteria. Rapidly obtained...

  9. Continuously operating dilution refrigerator with adsorption pumps

    International Nuclear Information System (INIS)

    Majdanov, V.A.; Mikhin, N.P.; Omelaenko, N.F.; Rudavskij, Eh.Ya.; Rybalko, A.S.; Chagovets, V.K.; Mikheev, V.A.

    1994-01-01

    The main parts and performance of two versions of the continuously operating dilution refrigerator with an adsorption pumping system dedicated to physical investigations at ultralow temperatures are described. Compared to conventional dilution refrigerators these versions are more compact, economic and more vibration proof. This type of dilution refrigerator allows a single shot operation to be realized. The minimum temperature reached in a single continuous heat exchanger refrigerator is 18 mK for a continuous operation and 5 - 8 mK for a single shot are. On addition of four discrete heat exchangers, the minimum temperature for continuous operation reduces down to 8 mK

  10. Deuterium and oxygen-18 isotope dilution spaces in normal adults

    International Nuclear Information System (INIS)

    Wong, W.; Cochran, W.; Lee, L.; Klish, W.; Klein, P.

    1986-01-01

    In light of the limited series of published comparison the authors have determined the deuterium and oxygen-18 isotope dilution spaces in 10 normal subjects, 5 males and 5 females. Labeled water was administered orally at doses of 40 mg deuterium oxide and 60 mg oxygen-18 per kg of body weight. One predose blood sample and six hourly postdose blood samples were collected from each subject. Aliquots of plasma water were reduced directly to hydrogen gas with zinc shot in individual quartz reaction vessels and 2 H/ 1 H isotope ratios were determined by gas-isotope-ratio mass spectrometry (GIRMS). 18 O/ 16 O isotope ratios were determined after plasma samples were equilibrated with CO 2 in an isotope exchange system. Both 2 H- and 18 O-labeled water attained isotopic equilibrium in plasma within 3 hr after administration. The deuterium dilution spaces in males and females were 56.4 +/- 2.1% (mean +/- SD) and 55.9 +/- 0.9% of body weight, respectively, while the 18 O dilution spaces constituted 54.1 +/- 1.85% and 53.30 +/- 1.30%. The deuterium spaces were larger than the 18 O spaces by 4.55 +/- 0.56% in men and 4.78 +/- 1.63% in women and were significant at P < 0.01. These results compare with values of 3.81 +/- 2.66% for males (n = 6) and 1.10 +/- 2.67% for females (n = 2) previously reported by Schoeller et al

  11. Infliximab stability after reconstitution, dilution, and storage under refrigeration.

    Science.gov (United States)

    Beer, Paul M; Wong, Susan J; Schartman, Jerome P; Kulas, Karen E; Hartman, Coby L; Giganti, Monica; Falk, Naomi S

    2010-01-01

    The purpose of this study was to investigate the stability of reconstituted infliximab solutions and determine whether infliximab is suitable for compounding for potential intravitreal use. Infliximab was reconstituted, and the solution was aliquoted and stored refrigerated. On each day of testing, an aliquot was serially diluted to concentrations ranging from 50,000 pg/mL to 69 pg/mL. Each dilution was assayed by microsphere immunoassay daily for 5 days and weekly for a total of 6 weeks. The outcome measure was median fluorescence intensity measured by dual laser flow analysis of fluorochrome-labeled secondary antibodies to infliximab bound to tumor necrosis factor-alpha-coated microspheres. There was an increasing median fluorescence intensity for increasing infliximab concentration in a sigmoidal dose-response curve with a variable slope that was equivalent for each time point. Each respective concentration of infliximab showed nearly equivalent median fluorescence intensity for every time point over the 6-week period. The authors found that the immunoreactivity of 2 different concentrations of infliximab stored at 4 degrees C over a 6-week period remained stable. Infliximab is suitable for compounding and could be a cost-effective intravitreal medication for use in clinical practice if further study supports its safety and efficacy.

  12. Tumor necrosis factor-alpha modulates human in vivo lipolysis

    DEFF Research Database (Denmark)

    Plomgaard, Peter; Fischer, Christian P; Ibfelt, Tobias

    2008-01-01

    in lipolysis, increasing circulatory free fatty acid (FFA) levels. SUBJECTS AND METHODS: Using a randomized controlled, crossover design, healthy young male individuals (n = 10) received recombinant human (rh) TNF-alpha (700 ng/m(-2).h(-1)) for 4 h, and energy metabolism was evaluated using a combination...... of tracer dilution methodology and arterial-venous differences over the leg. RESULTS: Plasma TNF-alpha levels increased from 0.7 +/- 0.04 to 16.7 +/- 1.8 pg/ml, and plasma IL-6 increased from 1.0 +/- 0.2 to 9.2 +/- 1.0 pg/ml (P rhTNF-alpha infusion. Here, we demonstrate that 4-h rh......TNF-alpha infusion increases whole body lipolysis by 40% (P rhTNF-alpha infusion. CONCLUSION...

  13. Gluconeogenesis from labeled carbon: estimating isotope dilution

    International Nuclear Information System (INIS)

    Kelleher, J.K.

    1986-01-01

    To estimate the rate of gluconeogenesis from steady-state incorporation of labeled 3-carbon precursors into glucose, isotope dilution must be considered so that the rate of labeling of glucose can be quantitatively converted to the rate of gluconeogenesis. An expression for the value of this isotope dilution can be derived using mathematical techniques and a model of the tricarboxylic acid (TCA) cycle. The present investigation employs a more complex model than that used in previous studies. This model includes the following pathways that may affect the correction for isotope dilution: 1) flux of 3-carbon precursor to the oxaloacetate pool via acetyl-CoA and the TCA cycle; 2) flux of 4- or 5-carbon compounds into the TCA cycle; 3) reversible flux between oxaloacetate (OAA) and pyruvate and between OAA and fumarate; 4) incomplete equilibrium between OAA pools; and 5) isotope dilution of 3-carbon tracers between the experimentally measured pool and the precursor for the TCA-cycle OAA pool. Experimental tests are outlined which investigators can use to determine whether these pathways are significant in a specific steady-state system. The study indicated that flux through these five pathways can significantly affect the correction for isotope dilution. To correct for the effects of these pathways an alternative method for calculating isotope dilution is proposed using citrate to relate the specific activities of acetyl-CoA and OAA

  14. Minimal coital dilution in Accra, Ghana.

    Science.gov (United States)

    Jenness, Samuel M; Biney, Adriana A E; Ampofo, William K; Nii-Amoo Dodoo, Francis; Cassels, Susan

    2015-05-01

    Coital dilution, the reduction in the coital frequency per partner when an additional ongoing partner is added, may reduce the transmission potential of partnership concurrency for HIV and other sexually transmitted infections. Empirical estimates of dilution, especially dilution of sexual acts unprotected by condoms, are needed to inform prevention research. Sexually active adults in Accra, Ghana were recruited in a multistage household probability sample. Degree (number of ongoing partners), total acts, and unprotected acts were measured retrospectively for each month in the past year through an event history calendar. Random-effects negative binomial models estimated the association between degree and coital frequency. Compared with person-months with a single partner (monogamy), 2.06 times as many total acts and 1.94 times as many unprotected acts occurred in months with 2 partners. In months with 3 partners, 2.90 times as many total acts and 2.39 times as many unprotected acts occurred compared with monogamous months. Total acts but not unprotected acts also declined with partnership duration. No dilution was observed for total acts with up to 3 concurrent partners, but a small amount of dilution was observed for unprotected acts for months with multiple concurrencies. This suggests moderate selective condom use in months with multiple concurrencies. The implications of the observed dilution for future HIV transmission must be investigated with mathematical models.

  15. Liquid chromatography-high resolution mass spectrometry with immunoaffinity clean-up for the determination of the oxidative stress biomarker 8-iso-prostaglandin F2alpha in wastewater.

    Science.gov (United States)

    Ryu, Yeonsuk; Reid, Malcolm J; Thomas, Kevin V

    2015-08-28

    A reliable oxidative stress biomarker, 8-iso-prostaglandin F2α (8-iso-PGF2α), was for the first time quantitatively analysed in wastewater using an analytical method consisting of liquid chromatography-high resolution mass spectrometry coupled to immunoaffinity clean-up (IAC-LC-HRMS). Factors influencing the method's robustness were investigated, including analyte stability in sewage and enzymatic deconjugation with β-glucuronidase. The IAC-LC-HRMS method was linear over the range of 0.1-100ng/mL with correlation coefficient (R(2)) of 0.999. The quantification limits were sufficiently low to detect 8-iso-PGF2α in sewage (method quantification limit of 0.3ng/L) and precision, expressed as relative standard deviation was less than 7% and the accuracy expressed as relative recovery was in the 103-113% range. As a result, the application of the method to 24-h composite wastewater samples from Oslo showed 8-iso-PGF2α concentrations of 18.9-23.3ng/L for 8 days in March 2015. This study demonstrates a standard method to analyse 8-iso-PGF2α in sewage that will contribute to the further investigation of the potential use of 8-iso-PGF2α as a sewage biomarker for assessing the status of community health. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Suicide attempt with a mix of synthetic cannabinoids and synthetic cathinones: Case report of non-fatal intoxication with AB-CHMINACA, AB-FUBINACA, alpha-PHP, alpha-PVP and 4-CMC.

    Science.gov (United States)

    Klavž, Janez; Gorenjak, Maksimiljan; Marinšek, Martin

    2016-08-01

    We report on a case of intoxication with a mix of new psychoactive substances. A 38-year-old male was brought to the emergency department (ED) following the ingestion of an unknown drug in a suicide attempt. During the transport, he became progressively more somnolent and unresponsive to painful stimuli. Urine and stomach content were collected on admission to be screened for drugs of abuse and medicinal drugs. After admission, the patient's next of kin presented five small grip seal plastic bags containing different powders/crystals, and they were sent for analysis along with urine and stomach content to the toxicology laboratory. An easy and rapid sample preparation technique was applied for the extraction of urine and stomach content. Samples were extracted with liquid-liquid extraction (LLE) technique and analysed using gas chromatography-mass spectrometry (GC-MS). A small amount of powder material from the bags was diluted in methanol and injected directly into the GC-MS instrument. Obtained spectra (EI) were evaluated against SWGDRUG library. Five different designer drugs were identified in the powder material, including synthetic cannabinoids (AB-CHMINACA, AB-FUBINACA) and synthetic cathinones (alpha-PHP, alpha-PVP and 4-CMC). With the exception of 4-CMC, all of these substances were also detected in the stomach content along with the prescription drugs. This is the first time that a positive identification of these five drugs has been made by a clinical laboratory in Slovenia. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. Application of atomic and nuclear techniques to the study of inhomogeneities in electrodeposited {alpha}-particle sources

    Energy Technology Data Exchange (ETDEWEB)

    Martin Sanchez, A. E-mail: ams@unex.es; Nuevo, M.J.; Jurado Vargas, M.; Diaz Bejarano, J.; Silva, M.F. da; Roldan Garcia, C.; Paul, A.; Ferrero Calabuig, J.L.; Mendez Vilas, A.; Juanes Barber, D

    2002-05-01

    Three {alpha}-particle sources made by different methods of electrodeposition were analysed using {alpha}-particle spectrometry, Rutherford backscattering (RBS), and atomic force microscopy (AFM) on several surface zones. The thickness and homogeneity of these sources was studied using RBS, and the results were analysed jointly with those obtained with {alpha}-particle spectrometry and AFM techniques. The comparison of the electrodeposition methods showed that the most homogeneous electrodeposited zones corresponded to the source made with a stirring cathode.

  18. Liquid-scintillation alpha-detection techniques

    International Nuclear Information System (INIS)

    McKlveen, J.W.; McDowell, W.J.

    1983-01-01

    Accurate, quantitative determinations of alpha-emitting nuclides by conventional plate-counting methods are difficult because of sample self-absorption problems in counting and because of non-reproducible losses in conventional sample separation methods. Liquid scintillation alpha spectrometry offers an attractive with no sample self-absorption or geometry problems and with 100% counting efficiency. Sample preparation may include extraction of the alpha emitter of interest by a specific organic-phase-soluble compound directly into the liquid scintillation counting medium. Detection electronics use energy and pulse-shape discrimination to yield alpha spectra without beta and gamma background interference. Specific procedures have been developed for gross alpha, uranium, plutonium, thorium, and polonium assay. Possibilities for a large number of other applications exist. Accuracy and reproducibility are typically in the 1% range. Backgrounds on the order of 0.01 cpm are readily achievable. The paper will present an overview of liquid scintillation alpha counting techniques and some of the results achieved for specific applications

  19. [Mass spectrometry of triterpene glycosides molecular complexation with purine bases of nucleic acids].

    Science.gov (United States)

    Lekar', A V; Vetrova, E V; Borisenko, N I; Iakovishin, L A; Grishkovets, V I

    2011-01-01

    The molecular complexation of adenine and guanine with hederagenin 3-O-alpha-L-rhamnopyranosyl-(1-->2)-O-alpha-L-arabinopyranoside (alpha-hederin) and its 28-O-alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-O-beta-D-glucopyranosyl ester (hederasaponin C) was investigated for the first time using the method of electrospray ionization mass spectrometry. Guanine forms complexes more diverse in composition than adenine.

  20. Dilution refrigeration with multiple mixing chambers

    International Nuclear Information System (INIS)

    Coops, G.M.

    1981-01-01

    A dilution refrigerator is an instrument to reach temperatures in the mK region in a continuous way. The temperature range can be extended and the cooling power can be enlarged by adding an extra mixing chamber. In this way we obtain a double mixing chamber system. In this thesis the theory of the multiple mixing chamber is presented and tested on its validity by comparison with the measurements. Measurements on a dilution refrigerator with a circulation rate up to 2.5 mmol/s are also reported. (Auth.)

  1. Diluted magnetic semiconductor nanowires exhibiting magnetoresistance

    Science.gov (United States)

    Yang, Peidong [El Cerrito, CA; Choi, Heonjin [Seoul, KR; Lee, Sangkwon [Daejeon, KR; He, Rongrui [Albany, CA; Zhang, Yanfeng [El Cerrito, CA; Kuykendal, Tevye [Berkeley, CA; Pauzauskie, Peter [Berkeley, CA

    2011-08-23

    A method for is disclosed for fabricating diluted magnetic semiconductor (DMS) nanowires by providing a catalyst-coated substrate and subjecting at least a portion of the substrate to a semiconductor, and dopant via chloride-based vapor transport to synthesize the nanowires. Using this novel chloride-based chemical vapor transport process, single crystalline diluted magnetic semiconductor nanowires Ga.sub.1-xMn.sub.xN (x=0.07) were synthesized. The nanowires, which have diameters of .about.10 nm to 100 nm and lengths of up to tens of micrometers, show ferromagnetism with Curie temperature above room temperature, and magnetoresistance up to 250 Kelvin.

  2. The determination of $\\alpha_s$ by the ALPHA collaboration

    CERN Document Server

    Bruno, Mattia

    2016-01-01

    We review the ALPHA collaboration strategy for obtaining the QCD coupling at high scale. In the three-flavor effective theory it avoids the use of perturbation theory at $\\alpha > 0.2$ and at the same time has the physical scales small compared to the cutoff $1/a$ in all stages of the computation. The result $\\Lambda_\\overline{MS}^{(3)}=332(14)$~MeV is translated to $\\alpha_\\overline{MS}(m_Z)=0.1179(10)(2)$ by use of (high order) perturbative relations between the effective theory couplings at the charm and beauty quark "thresholds". The error of this perturbative step is discussed and estimated as $0.0002$.

  3. What infusion flow should be used for mid-dilution hemodiafiltration?

    Science.gov (United States)

    Maduell, Francisco; Arias, Marta; Fontseré, Néstor; Vera, Manel; Masso, Elisabeth; Garro, Julia; Barros, Xoana; Martina, Maria N; Elena, Montserrat; Bergadá, Eduardo; Cases, Aleix; Bedini, Jose Luis; Campistol, Josep M

    2010-01-01

    There is still no consensus on the optimal infusion flow (Qi) in mid-dilution hemodiafiltration. The aim of this study was to compare mid-dilution with varying Qi. Prospective study in 25 patients who underwent seven hemodialysis sessions with a Qi of 0, 50, 100, 150, 200, 250 and 300 ml/min. All sessions were well tolerated except Qi 300 ml/min. No significant differences in urea, creatinine, alpha(1)-microglobulin or alpha(1)-acid glycoprotein reduction ratios were observed. beta(2)-Microglobulin, myoglobin and prolactin reduction ratios were higher with Qi 150, 200, 250 and 300 ml/min in comparison with Qi of 0, 50 and 100 ml/min. There were no differences in the removal of small or larger molecules when Qi was 150 ml/min or higher. Optimal Qi in mid-dilution appears to be in the range of 150-250 ml/min since good clinical outcomes, similar efficiency and no technical complications up to a Qi of 250 ml/min were observed.

  4. Analyzing the uncorrected error of dilution water demand for the dilution biochemical oxygen demand method.

    Science.gov (United States)

    Chiang, Chow F; Wu, Yeong S; Young, James C

    2004-01-01

    Dilution water demand (DWD) can cause a positive error when the dilution biochemical oxygen demand (BOD) method is used. Dilution water demand may be attributed to oxidation of organic impurities in the dilution water and nitrification of ammonia added as a nutrient. To minimize the error associated with these sources, the standard BOD method requires that DWD be less than 0.2 mg/L in 5 days and does not allow correction for DWD when calculating test results. This study derives a set of theoretical equations to analyze the uncorrected errors with and without seeding. The authors concluded that DWD can be completely corrected if seeded dilution water is used for the sample dilution. When seeding individual bottles, the uncorrected error approaches 8.3 to approximately 8.8% at a 5-day depletion of 2 mg/L for a typical secondary effluent. Tests without seeding show an almost 1% higher uncorrected error than seeded tests. The analysis also suggests that these errors can be effectively reduced to less than 3% when the 5-day depletion approaches 6 mg/L. even for 5-day biochemical oxygen demand concentrations exceeding I x 10(4) mg/L. Further analysis indicates that, if not inhibited, the ammonium added to dilution water as a nutrient may contribute additional error due to nitrification.

  5. Quantifying dilution caused by execution efficiency

    Directory of Open Access Journals (Sweden)

    Taís Renata Câmara

    Full Text Available Abstract In open pit mining, dilution is not always a factor systematically analyzed and calculated. Often it is only an adjusted number, for example, calculated or even empirically determined for a certain operational condition perpetuating along time in the form of a constant applied to calculating reserves or mine planning in attendance of audit requirements. Dilution and loss are factors that should be always considered for tonnage and grade estimates. These factors are always associated and can be determined considering several particularities of the deposit and the operation itself. In this study, a methodology was determined to identify blocks adjacent to the blocks previously planned to be mined. Thus, it is possible to estimate the dilution caused by poor operating efficiency, taking into account the inability of the equipment to perfectly remove each block, respecting its limits. Mining dilution is defined as the incorporation of waste material to ore due to the operational incapacity to efficiently separate the materials during the mining process, considering the physical processes, and the operating and geometric configurations of the mining with the equipment available.

  6. Dilution of whisky - the molecular perspective.

    Science.gov (United States)

    Karlsson, Björn C G; Friedman, Ran

    2017-08-17

    Whisky is distilled to around 70% alcohol by volume (vol-%) then diluted to about 40 vol-%, and often drunk after further slight dilution to enhance its taste. The taste of whisky is primarily associated with amphipathic molecules, such as guaiacol, but why and how dilution enhances the taste is not well understood. We carried out computer simulations of water-ethanol mixtures in the presence of guaiacol, providing atomistic details on the structure of the liquid mixture. We found that guaiacol is preferentially associated with ethanol, and, therefore, primarily found at the liquid-air interface in mixtures that contain up to 45 vol-% of ethanol. At ethanol concentrations of 59 vol-% or higher, guaiacol is increasingly surrounded by ethanol molecules and is driven to the bulk. This indicates that the taste of guaiacol in the whisky would be enhanced upon dilution prior to bottling. Our findings may apply to other flavour-giving amphipathic molecules and could contribute to optimising the production of spirits for desired tastes. Furthermore, it sheds light on the molecular structure of water-alcohol mixtures that contain small solutes, and reveals that interactions with the water may be negligible already at 89 vol-% of ethanol.

  7. Osmosis is not driven by water dilution.

    Science.gov (United States)

    Kramer, Eric M; Myers, David R

    2013-04-01

    There is a misconception among plant scientists that osmosis is driven by the tendency of solutes to dilute water. In this opinion article, we discuss the quantitative and qualitative failures of this view, and go on to review the correct kinetic picture of osmosis as it appears in physics textbooks. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Dilution kicker for the SPS beam dump

    CERN Multimedia

    1974-01-01

    In order to reduce thermal stress on the SPS dump material, the fast-ejected beam was swept horizontally across the dump. This was done with the "dilution kicker" MKDH, still in use at the time of writing. The person on the left is Manfred Mayer. See also 7404072X.

  9. Variational approach to the dilute Bose gas

    NARCIS (Netherlands)

    Bijlsma, M.; Stoof, H.T.C.

    1997-01-01

    We study the weakly interacting Bose gas in both two and three dimensions using a variational approach. In particular we construct the thermodynamic potential of the gas to within ladder approximation and find by minimization an accurate mean-field description of the dilute Bose gas. Using

  10. Atomic displacements in bcc dilute alloys

    Indian Academy of Sciences (India)

    We present here a systematic investigation of the atomic displacements in bcc transition metal (TM) dilute alloys. We have calculated the atomic displacements in bcc (V, Cr, Fe, Nb, Mo, Ta and W) transition metals (TMs) due to 3d, 4d and 5d TMs at the substitutional site using the Kanzaki lattice static method. Wills and ...

  11. Liquid volumes measurements by isotopic dilution

    International Nuclear Information System (INIS)

    Herrera M, J.M.

    1981-01-01

    By the nuclear technique, isotopic dilution industrial liquid volumes may be measured in large size recipients of irregular shapes using radiotracers. In the present work laboratory and pilot test are made with 2 radiotracers for optimizing the technique and later done on an industrial scale, obtaining a maximum deviation of +-2%, some recommendations are given to improve the performance of the technique. (author)

  12. Dilution kicker for the SPS beam dump

    CERN Multimedia

    1974-01-01

    In order to reduce thermal stress on the SPS dump material, the fast-ejected beam was swept horizontally across the dump. This was done with the "dilution kicker" MKDH, still in use at the time of writing. See also 7402051X.

  13. Atomic displacements in bcc dilute alloys

    Indian Academy of Sciences (India)

    Abstract. We present here a systematic investigation of the atomic displacements in bcc transition metal (TM) dilute alloys. We have calculated the atomic displacements in bcc. (V, Cr, Fe, Nb, Mo, Ta and W) transition metals (TMs) due to 3d, 4d and 5d TMs at the substitutional site using the Kanzaki lattice static method.

  14. Sulfuric Acid and Water: Paradoxes of Dilution

    Science.gov (United States)

    Leenson, I. A.

    2004-01-01

    On equilibrium properties of aqueous solutions of sulfuric acid, Julius Thomsen has marked that the heat evolved on diluting liquid sulfuric acid with water is a continuous function of the water used, and excluded absolutely the acceptance of definite hydrates as existing in the solution. Information about thermochemical measurement, a discussion…

  15. A simple deep monitoring well dilution technique.

    Science.gov (United States)

    Rogiers, Bart; Labat, Serge; Gedeon, Matej; Vandersteen, Katrijn

    2015-04-01

    Well dilution techniques are well known and studied as one of the basic techniques to quantify groundwater fluxes. A typical well dilution test consists of the injection of a tracer, a mixing mechanism (e.g. water circulation with a pump) to achieve a homogeneous concentration distribution within the well, and monitoring of the evolution of tracer concentration with time. An apparent specific discharge can be obtained from such a test, and when details on the well construction are known, it can be converted into a specific discharge representative of the undisturbed aquifer. For deep wells however, the injection of tracer becomes less practical and the use of pumps for circulating and mixing the water becomes problematic. This is due to the limited pressure that common pumps can endure at the outlet, as well as the large volume of water that makes it difficult to achieve a homogeneous concentration, and the impracticalities of getting a lot of equipment to large depths in very small monitoring wells. Injection and monitoring of tracer at a specific depth omits several of the problems with deep wells. We present a very simple device that can be used to perform a dilution test at a specific depth in deep wells. The injection device consists of a PVC tube with a detachable rubber seal at its bottom. To minimize disturbance of the water column in the well, we integrated an EC sensor in this injection device, which enables us to use demineralized water or dissolved salts as a tracer. Once at the target depth, the PVC tube is retracted and the EC sensor and tracer become subject to groundwater flow. The device was tested on a shallow well, on which different types of dilution tests were performed. The results of the other tests agree well with the injection tube results. Finally, the device was used to perform a dilution test in a deep well in order to demonstrate the feasibility of the approach.

  16. Spatio-temporal profiling and degradation of alpha-amylase isozymes during barley seed germination

    DEFF Research Database (Denmark)

    Bak-Jensen, K.S.; Laugesen, Sabrina; Østergaard, Ole

    2007-01-01

    Ten genes from two multigene families encode barley alpha-amylases. To gain insight into the occurrence and fate of individual isoforms during seed germination, the alpha-amylase repertoire was mapped by using a proteomics approach consisting of 2D gel electrophoresis, western blotting, and mass...... spectrometry. Mass spectrometric analysis confirmed that the 29 alpha-amylase positive 2D gel spots contained products of one ( GenBank accession gi| 113765) and two ( gi vertical bar 4699831 and gi vertical bar 166985) genes encoding alpha-amylase 1 and 2, respectively, but lacked products from seven other...... genes. Eleven spots were identified only by immunostaining. Mass spectrometry identified 12 full-length forms and 12 fragments from the cultivar Barke. Products of both alpha-amylase 2 entries co-migrated in five full-length and one fragment spot. The alpha-amylase abundance and the number of fragments...

  17. Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) in toxicological analysis. Studies on the detection of clobenzorex and its metabolites within a systematic toxicological analysis procedure by GC-MS and by immunoassay and studies on the detection of alpha- and beta-amanitin in urine by atmospheric pressure ionization electrospray LC-MS.

    Science.gov (United States)

    Maurer, H H; Kraemer, T; Ledvinka, O; Schmitt, C J; Weber, A A

    1997-02-07

    GC-MS is the method of choice for toxicological analysis of toxicants volatile in GC while non-volatile and/or thermally labile toxicants need LC-MS for their determination. Studies are presented on the toxicological detection of the amphetamine-like anorectic clobenzorex in urine by GC-MS after acid hydrolysis, extraction and acetylation and by fluorescence polarization immunoassay (FPIA, TDx (meth)amphetamine II). After ingestion of 60 mg of clobenzorex, the parent compound and/or its metabolites could be detected by GC-MS for up to 84 h or by FPIA for up to 60 h. Since clobenzorex shows no cross-reactivity with the used immunoassay, the N-dealkylated metabolite amphetamine is responsible for the positive TDx results. The intake of clobenzorex instead of amphetamine can be differentiated by GC-MS detection of hydroxyclobenzorex which is detectable for at least as long as amphetamine. In addition, the described GC-MS procedure allows the simultaneous detection of most of the toxicologically relevant drugs. Furthermore, studies are described on the atmospheric pressure ionization electrospray LC-MS detection of alpha- and beta-amanitin, toxic peptides of amanita mushrooms, in urine after solid-phase extraction on RP-18 columns. Using the single ion monitoring mode with the ions m/z 919 and 920 the amanitins could be detected down to 10 ng/ml of urine which allows us to diagnose intoxications with amanita mushrooms.

  18. Measurement of LNAPL flow using single-well tracer dilution techniques.

    Science.gov (United States)

    Sale, Tom; Taylor, Geoffrey Ryan; Iltis, Gabriel; Lyverse, Mark

    2007-01-01

    This paper describes the use of single-well tracer dilution techniques to resolve the rate of light nonaqueous phase liquid (LNAPL) flow through wells and the adjacent geologic formation. Laboratory studies are presented in which a fluorescing tracer is added to LNAPL in wells. An in-well mixer keeps the tracer well mixed in the LNAPL. Tracer concentrations in LNAPL are measured through time using a fiber optic cable and a spectrometer. Results indicate that the rate of tracer depletion is proportional to the rate of LNAPL flow through the well and the adjacent formation. Tracer dilution methods are demonstrated for vertically averaged LNAPL Darcy velocities of 0.00048 to 0.11 m/d and LNAPL thicknesses of 9 to 24 cm. Over the range of conditions studied, results agree closely with steady-state LNAPL flow rates imposed by pumping. A key parameter for estimating LNAPL flow rates in the formation is the flow convergence factor alpha. Measured convergence factors for 0.030-inch wire wrap, 0.030-inch-slotted polyvinyl chloride (PVC), and 0.010-inch-slotted PVC are 1.7, 0.91, and 0.79, respectively. In addition, methods for using tracer dilution data to determine formation transmissivity to LNAPL are presented. Results suggest that single-well tracer dilution techniques are a viable approach for measuring in situ LNAPL flow and formation transmissivity to LNAPL.

  19. Lyman Alpha Control

    CERN Document Server

    Nielsen, Daniel Stefaniak

    2015-01-01

    This document gives an overview of how to operate the Lyman Alpha Control application written in LabVIEW along with things to watch out for. Overview of the LabVIEW code itself as well as the physical wiring of and connections from/to the NI PCI-6229 DAQ box is also included. The Lyman Alpha Control application is the interface between the ALPHA sequencer and the HighFinesse Wavelength Meter as well as the Lyman Alpha laser setup. The application measures the wavelength of the output light from the Lyman Alpha cavity through the Wavelength Meter. The application can use the Wavelength Meter’s PID capabilities to stabilize the Lyman Alpha laser output as well as switch between up to three frequencies.

  20. New ALPHA-2 magnet

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    On 21 June, members of the ALPHA collaboration celebrated the handover of the first solenoid designed for the ALPHA-2 experiment. The magnet has since been successfully installed and is working well.   Khalid Mansoor, Sumera Yamin and Jeffrey Hangst in front of the new ALPHA-2 solenoid. “This was the first of three identical solenoids that will be installed between now and September, as the rest of the ALPHA-2 device is installed and commissioned,” explains ALPHA spokesperson Jeffrey Hangst. “These magnets are designed to allow us to transfer particles - antiprotons, electrons and positrons - between various parts of the new ALPHA-2 device by controlling the transverse size of the particle bunch that is being transferred.” Sumera Yamin and Khalid Mansoor, two Pakistani scientists from the National Centre for Physics in Islamabad, came to CERN in February specifically to design and manufacture these magnets. “We had the chance to work on act...

  1. Plutonium determination in urine by techniques of mass spectrometry

    International Nuclear Information System (INIS)

    Hernandez M, H.; Yllera de Ll, A.

    2013-10-01

    The objective of this study was to develop an analytic method for quantification and plutonium reappraisal in plane tables of alpha spectrometry be means of the mass spectrometry technique of high resolution with plasma source inductively coupled and desolvator Aridus (Aridus-Hr-Icp-Ms) and mass spectrometry with accelerator (AMS). The obtained results were, the recovery percentage of Pu in the plane table was of ∼ 90% and activity minimum detectable obtained with Aridus-Hr-Icp-Ms and AMS was of ∼ 3 and ∼ 0.4 f g of 239 Pu, respectively. Conclusion, the results demonstrate the aptitude of the Aridus-Hr-Icp-Ms and AMS techniques in the Pu reappraisal in plane tables with bigger speed and precision, improving the values notably of the activity minimum detectable that can be obtained with the alpha spectrometry (∼ 50 f g of 239 Pu). (author)

  2. Quantification of active infliximab in human serum with liquid chromatography-tandem mass spectrometry using a tumor necrosis factor alpha -based pre-analytical sample purification and a stable isotopic labeled infliximab bio-similar as internal standard: A target-based, sensitive and cost-effective method.

    Science.gov (United States)

    El Amrani, Mohsin; van den Broek, Marcel P H; Göbel, Camiel; van Maarseveen, Erik M

    2016-07-08

    The therapeutic monoclonal antibody Infliximab (IFX) is a widely used drug for the treatment of several inflammatory autoimmune diseases. However, approximately 10% of patients develop anti-infliximab antibodies (ATIs) rendering the treatment ineffective. Early detection of underexposure to unbound IFX would result in a timely switch of therapy which could aid in the treatment of this disease. Streptavidin coated 96 well plates were used to capture biotinylated-tumor necrosis factor -alpha (b-TNF-α), which in turn was used to selectively extract the active form of IFX in human serum. After elution, IFX was digested using trypsin and one signature peptide was selected for subsequent analysis on liquid chromatography-tandem mass spectrometry (LC-MS/MS). The internal standard used was a stable isotopic labeled IFX bio-similar. The assay was successfully validated according to European Medicines Agency (EMA) guidelines and was found to be linear in a range of 0.5-20μg/mL (r(2)=0.994). Lower limit of quantification for the assay (<20% CV) was 0.5μg/mL, requiring only 2μL of sample. Cross-validation against enzyme-linked immunosorbent assay (ELISA) resulted in a high correlation between methods (r(2)=0.95 with a ρc=0.83) and the accuracy was in line with previously published results. In conclusion, a sensitive, robust and cost-effective method was developed for the bio-analysis of IFX with LC-MS/MS by means of a target-based pre-analytical sample purification. Moreover, low volume and costs of consumables per sample promote its feasibility in (pre)clinical studies and in therapeutic drug monitoring. This method should be considered as first choice due to its accuracy and multiple degree of selectivity. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Mass spectrometry in nuclear science and technology

    International Nuclear Information System (INIS)

    Komori, Takuji

    1985-01-01

    Mass spectrometry has been widely used and playing a very important role in the field of nuclear science and technology. A major reason for this is that not only the types of element but also its isotopes have to be identified and measured in this field. Thus, some applications of this analytical method are reviewed and discussed in this article. Its application to analytical chemistry is described in the second section following an introductory section, which includes subsections for isotropic dilution mass spectrometry, resonance ionization mass spectrometry and isotopic correlation technique. The isotopic ratio measurement for hydrogen, uranium and plutonium as well as nuclear material control and safeguards are also reviewed in this section. In the third section, mass spectrometry is discussed in relation to nuclear reactors, with subsections on natural uranium reactor and neutron flux observation. Some techniques for measuring the burnup fraction, including the heavy isotopic ratio method and fission product monitoring, are also described. In the fourth section, application of mass spectrometry to measurement of nuclear constants, such as ratio of effective cross-sectional area for 235 U, half-life and fission yield is reviewed. (Nogami, K.)

  4. Reverse isotope dilution method for determining benzene and metabolites in tissues

    International Nuclear Information System (INIS)

    Bechtold, W.E.; Sabourin, P.J.; Henderson, R.F.

    1988-01-01

    A method utilizing reverse isotope dilution for the analysis of benzene and its organic soluble metabolites in tissues of rats and mice is presented. Tissues from rats and mice that had been exposed to radiolabeled benzene were extracted with ethyl acetate containing known, excess quantities of unlabeled benzene and metabolites. Butylated hydroxytoluene was added as an antioxidant. The ethyl acetate extracts were analyzed with semipreparative reversed-phase HPLC. Isolated peaks were collected and analyzed for radioactivity (by liquid scintillation spectrometry) and for mass (by UV absorption). The total amount of each compound present was calculated from the mass dilution of the radiolabeled isotope. This method has the advantages of high sensitivity, because of the high specific activity of benzene, and relative stability of the analyses, because of the addition of large amounts of unlabeled carrier analogue

  5. Alpha Shapes and Proteins

    DEFF Research Database (Denmark)

    Winter, Pawel; Sterner, Henrik; Sterner, Peter

    2009-01-01

    We provide a unified description of (weighted) alpha shapes, beta shapes and the corresponding simplicialcomplexes. We discuss their applicability to various protein-related problems. We also discuss filtrations of alpha shapes and touch upon related persistence issues.We claim that the full...... potential of alpha-shapes and related geometrical constructs in protein-related problems yet remains to be realized and verified. We suggest parallel algorithms for (weighted) alpha shapes, and we argue that future use of filtrations and kinetic variants for larger proteins will need such implementation....

  6. Application of Micro-coprecipitation Method to Alpha Source Preparation for Measuring Alpha Nuclides

    International Nuclear Information System (INIS)

    Lee, Myung Ho; Park, Jong Ho; Oh, Se Jin; Song, Byung Chul; Song, Kyuseok

    2011-01-01

    Among the source preparations, an electrodeposition is a commonly used method for the preparation of sources for an alpha spectrometry, because this technique is simple and produces a very thin deposit, which is essential for a high resolution of the alpha peak. Recently, micro-coprecipitation with rare earths have been used to yield sources for -spectrometry. In this work, the Pu, Am and Cm isotopes were purified from hindrance nuclides and elements with an a TRU resin in radioactive waste samples, and the activity concentrations of the Pu, Am and Cm isotopes were determined by radiation counting methods after alpha source preparation like micro coprecipitation. After the Pu isotopes in the radioactive waste samples were separated from the other nuclides with an anion exchange resin, the Am isotopes were purified with a TRU resin and an anion exchange resin or a TRU resin. Activity concentrations and chemical recoveries of 241 Am purified with the TRU resin were similar to those with the TRU resin and anion exchange resin. In this study, to save on the analytical time and cost, the Am isotopes were purified with the TRU resin without using an additional anion exchange resin. After comparing the electrodeposition method with the micro-coprecipitation method, the micro-coprecipitation method was used for the alpha source preparation, because the micro-coprecipitation method is simple and more reliable for source preparation of the Pu, Am and Cm isotopes

  7. Targeted Alpha Therapy: From Alpha to Omega

    International Nuclear Information System (INIS)

    Allen, Barry J; Clarke, Raymond; Huang Chenyu

    2013-01-01

    This review covers the broad spectrum of Targeted Alpha Therapy (TAT) research in Australia; from in vitro and in vivo studies to clinical trials. The principle of tumour anti-vascular alpha therapy (TAVAT) is discussed in terms of its validation by Monte Carlo calculations of vascular models and the potential role of biological dosimetry is examined. Summmary of this review is as follows: 1. The essence of TAT 2. Therapeutic objectives 3. TAVAT and Monte Carlo microdosimetry 4. Biological dosimetry 5. Preclinical studies 6. Clinical trials 7. What next? 8. Obstacles. (author)

  8. Dynamic Dilution Effects in Polymeric Networks

    DEFF Research Database (Denmark)

    Skov, Anne Ladegaard; Sommer-Larsen, Peter; Hassager, Ole

    2006-01-01

    The relaxation processes occurring in slightly and well-entangled polydimetylsiloxane ( PDMS) networks are investigated. Swelling experiments are performed in order to determine the sol fractions. The low-frequency linear rheology of the two types of networks reveal two significant relaxation pro...... by the change in the amount of dangling arms and solubles with stoichiometry. The star arm relaxation is suppressed by washing out the sol fraction which is seen as a clear example of the dynamic dilution effect arising from the small amount of non-reactive PDMS....... processes, namely the reptation of linear species within the network and the arm withdrawal process of star arms in the sol fraction and of dangling single-chain ends attached to the network. The relaxation spectra are influenced by the stoichiometry to a large extent due to dynamic dilution effects caused...

  9. Dilute nanoemulsions via separation of satellite droplets.

    Science.gov (United States)

    Deen, Shad; Sajjadi, Shahriar

    2013-10-01

    A facile method is suggested for fabrication of dilute nanoemulsions. In a typical emulsification process, drops are usually accompanied by off-grade satellite droplets. The size of these satellite droplets ranges from hundreds of nanometers to above microns. Experiments were carried out to assess the possibility of separation of nanodrops from macroemulsions made via a conventional method in order to produce nanoemulsions. A low-power homogenizer was used to produce parent emulsions which were then injected from the bottom to a glass column containing water and allowed to cream. By monitoring drops remaining in the bottom of the column, it is clearly shown how progressively smaller they become with time yielding eventually dilute nanoemulsions. The average diameter of drops reduced to 100 nm when oil with high viscosity was used. The concentration of resulting nanoemulsions increased with increasing viscosity and ratio of the disperse phase of parent emulsions. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Isotope dilution analysis of environmental samples

    International Nuclear Information System (INIS)

    Tolgyessy, J.; Lesny, J.; Korenova, Z.; Klas, J.; Klehr, E.H.

    1986-01-01

    Isotope dilution analysis has been used for the determination of several trace elements - especially metals - in a variety of environmental samples, including aerosols, water, soils, biological materials and geological materials. Variations of the basic concept include classical IDA, substoichiometric IDA, and more recently, sub-superequivalence IDA. Each variation has its advantages and limitations. A periodic chart has been used to identify those elements which have been measured in environmental samples using one or more of these methods. (author)

  11. Vitamins D and A can be successfully measured by LC-MS/MS in cord blood diluted plasma.

    Science.gov (United States)

    Albarhani, Ali A; Collier, Fiona; Greaves, Ronda F; Ponsonby, Anne-Louise; Allen, Katrina J; Vuillermin, Peter J; Roche, Peter; Clarke, Michael W

    2015-11-01

    In widely used protocols for the collection and isolation of cord blood mononuclear cells, investigators are left with substantial volumes of diluted plasma which could be used for other measurements. The aim of this study was to ascertain the validity of umbilical cord blood (UCB) diluted plasma samples for vitamin D, A and E analysis compared to UCB serum samples. Twenty UCB matched samples of diluted plasma and serum were collected. The samples were analysed by two liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods on two separate occasions. The results of 25(OH)D3 obtained by the two laboratories demonstrated close agreement with a mean difference of 0.14nmol/L [95% confidence interval (95% CI), -6.8 to 7.1]. Both methods demonstrate close agreement for 25(OH)D3 in UCB serum versus diluted UCB plasma; mean difference 2.2nmol/L [95% CI, -9.5 to 13.9] and 4.1nmol/L [95% CI, -14.5 to 6.1] for the results from Lab A and Lab B, respectively. Vitamin A was quantified by Lab A in UCB serum and diluted UCB plasma; mean difference 0.07μmol/L [95% CI, -0.41 to 0.28]. Results of 25(OH)D3 epimer and vitamin E in the diluted UCB plasma were below the limit of quantification, and could not be compared with UCB serum. Diluted UCB plasma can be used for the quantification of retinol and 25(OH)D3 by LC-MS/MS. By contrast, quantification of 25(OH)D3 epimer and vitamin E in diluted UCB plasma is not supported by this study due to limitations in analytical sensitivity. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  12. Alpha1-antitrypsin deficiency

    DEFF Research Database (Denmark)

    Stolk, Jan; Seersholm, Niels; Kalsheker, Noor

    2006-01-01

    The Alpha One International Registry (AIR), a multinational research program focused on alpha1-antitrypsin (AAT) deficiency, was formed in response to a World Health Organization recommendation. Each of the nearly 20 participating countries maintains a national registry of patients with AAT defic...... epidemiology, inflammatory and signalling processes, therapeutic advances, and lung imaging techniques....

  13. Alpha clustering in nuclei

    International Nuclear Information System (INIS)

    Hodgson, P.E.

    1990-01-01

    The effects of nucleon clustering in nuclei are described, with reference to both nuclear structure and nuclear reactions, and the advantages of using the cluster formalism to describe a range of phenomena are discussed. It is shown that bound and scattering alpha-particle states can be described in a unified way using an energy-dependent alpha-nucleus potential. (author)

  14. Production of fungal alpha-amylase by Saccharomyces kluyveri in glucose-limited cultivations

    DEFF Research Database (Denmark)

    Møller, Kasper; Sharif, M.Z.; Olsson, Lisbeth

    2004-01-01

    and S. cerevisiae were transformed with the same plasmid, which led to secretion of active alpha-amylase in both cases. The S. cerevisiae 2 mu plasmid was found to be stable in S. kluyveri as evaluated by a constant alpha-amylase productivity in a continuous cultivation for more than 40 generations. S......Heterologous protein production by the yeast Saccharomyces kluyveri was investigated under aerobic glucose-limited conditions. alpha-Amylase from Aspergillus oryzae was used as model protein and the gene was expressed from a S. cerevisiae 2 mu plasmid. For comparison, strains of both S. kluyveri....... kluyveri and S. cerevisiae secreted alpha-amylase with similar yields during continuous cultivations at dilution rates of 0.1 and 0.2 h(-1) (4.8-5.7 mg (g dry weight)(-1)). At a dilution rate of 0.3 h(-1) the metabolism of S. kluyveri was fully respiratory, whereas S. cerevisiae produced significant...

  15. Production of fungal alpha-amylase by Saccharomyces kluyveri in glucose-limited cultivations

    DEFF Research Database (Denmark)

    Møller, Kasper; Sharif, M.Z.; Olsson, Lisbeth

    2004-01-01

    Heterologous protein production by the yeast Saccharomyces kluyveri was investigated under aerobic glucose-limited conditions. alpha-Amylase from Aspergillus oryzae was used as model protein and the gene was expressed from a S. cerevisiae 2 mu plasmid. For comparison, strains of both S. kluyveri...... and S. cerevisiae were transformed with the same plasmid, which led to secretion of active alpha-amylase in both cases. The S. cerevisiae 2 mu plasmid was found to be stable in S. kluyveri as evaluated by a constant alpha-amylase productivity in a continuous cultivation for more than 40 generations. S....... kluyveri and S. cerevisiae secreted alpha-amylase with similar yields during continuous cultivations at dilution rates of 0.1 and 0.2 h(-1) (4.8-5.7 mg (g dry weight)(-1)). At a dilution rate of 0.3 h(-1) the metabolism of S. kluyveri was fully respiratory, whereas S. cerevisiae produced significant...

  16. Role of valence electrons in phase transformation kinetics of thallium and its dilute alloys

    Science.gov (United States)

    Ahmed, R.; Ahmed, S.

    1991-01-01

    The kinetics of the phase transformation of thallium and its dilute alloys were investigated using XRD and calorimetry. Pure thallium exhibits a beta(bcc) to alpha(hcp) phase transformation on cooling at 508 K. With alloying additions, the crystal structure for each phase does not change, although the size of the unit cell increases. The enthalpy and the temperature of phase transformation of each alloy have been determined. The chemical free energy change associated with the phase transformation of each alloy was calculated. The valence electrons make an outstanding contribution to the chemical free energy change required for the phase change.

  17. Molecular analysis of two mouse dilute locus deletion mutations: Spontaneous dilute lethal20J and radiation-induced dilute prenatal lethal Aa2 alleles

    International Nuclear Information System (INIS)

    Strobel, M.C.; Seperack, P.K.; Copeland, N.G.; Jenkins, N.A.

    1990-01-01

    The dilute (d) coat color locus of mouse chromosome 9 has been identified by more than 200 spontaneous and mutagen-induced recessive mutations. With the advent of molecular probes for this locus, the molecular lesion associated with different dilute alleles can be recognized and precisely defined. In this study, two dilute mutations, dilute-lethal20J (dl20J) and dilute prenatal lethal Aa2, have been examined. Using a dilute locus genomic probe in Southern blot analysis, we detected unique restriction fragments in dl20J and Aa2 DNA. Subsequent analysis of these fragments showed that they represented deletion breakpoint fusion fragments. DNA sequence analysis of each mutation-associated deletion breakpoint fusion fragment suggests that both genomic deletions were generated by nonhomologous recombination events. The spontaneous dl20J mutation is caused by an interstitial deletion that removes a single coding exon of the dilute gene. The correlation between this discrete deletion and the expression of all dilute-associated phenotypes in dl20J homozygotes defines the dl20J mutation as a functional null allele of the dilute gene. The radiation-induced Aa2 allele is a multilocus deletion that, by complementation analysis, affects both the dilute locus and the proximal prenatal lethal-3 (pl-3) functional unit. Molecular analysis of the Aa2 deletion breakpoint fusion fragment has provided access to a previously undefined gene proximal to d. Initial characterization of this new gene suggests that it may represent the genetically defined pl-3 functional unit

  18. Improvement of sample preparation for input plutonium accountability measurement by isotope dilution gammy-ray spectroscopy

    International Nuclear Information System (INIS)

    Nishida, K.; Kuno, Y.; Sato, S.; Masui, J.; Li, T.K.; Parker, J.L.; Hakkila, E.A.

    1992-01-01

    The sample preparation method for the isotope dilution gamma-ray spectrometry (IDGS) technique has been further improved for simultaneously determining the plutonium concentration and isotopic composition of highly irradiated spent-fuel dissolver solutions. The improvement includes using ion-exchange filter papers (instead of resin beads, as in two previous experiments) for better separation and recovery of plutonium from fission products. The results of IDGS measurements for five dissolver solutions are in good agreement with those by mass spectrometry with ∼0.4% for plutonium concentration and ∼0.1% for 239 Pu isotopic composition. The precision of the plutonium concentration is ∼1% with a 1-h count time. The technique could be implemented as an alternative method for input accountability and verification measurements in reprocessing plants

  19. Nanocrystalline alpha-Fe Layer Examined by Mossbauer Spectrometry

    Czech Academy of Sciences Publication Activity Database

    David, Bohumil; Schneeweiss, Oldřich; Pizúrová, Naděžda; Rek, Antonín; Kudrle, V.; Jašek, J.

    2014-01-01

    Roč. 126, č. 1 (2014), s. 94-95 ISSN 0587-4246. [CSMAG Czech and Slovak Conference on Magnetism /15./. Košice, 17.06.2013-21.06.2013] R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 ; RVO:68081731 Keywords : nanostructured pure iron * microwave plasma * Mossbauer spectroscopy * TEM * SEM Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.530, year: 2014 http://przyrbwn.icm.edu.pl/ APP /PDF/126/a126z1p043.pdf

  20. Equilibria determination in uranium ores by alpha spectrometry

    International Nuclear Information System (INIS)

    Tormo Ferrero, M.J.

    1976-01-01

    A method for the measurement of the U-234/U-238 activities is described. The separation of the uranium from the interferring elements is carried out by ionic change with anionic resine, in chlorhydric-metanol-ascorbic acid medium. The method has been applied to different spanish ores in which the equilibrium state has been determined (author)

  1. [Sample preparation and bioanalysis in mass spectrometry].

    Science.gov (United States)

    Bourgogne, Emmanuel; Wagner, Michel

    2015-01-01

    The quantitative analysis of compounds of clinical interest of low molecular weight (sample preparation. Sample preparation is a crucial part of chemical/biological analysis and in a sense is considered the bottleneck of the whole analytical process. The main objectives of sample preparation are the removal of potential interferences, analyte preconcentration, and converting (if needed) the analyte into a more suitable form for detection or separation. Without chromatographic separation, endogenous compounds, co-eluted products may affect a quantitative method in mass spectrometry performance. This work focuses on three distinct parts. First, quantitative bioanalysis will be defined, different matrices and sample preparation techniques currently used in bioanalysis by mass spectrometry of/for small molecules of clinical interest in biological fluids. In a second step the goals of sample preparation will be described. Finally, in a third step, sample preparation strategies will be made either directly ("dilute and shoot") or after precipitation.

  2. Genetics Home Reference: alpha thalassemia

    Science.gov (United States)

    ... Facebook Twitter Home Health Conditions Alpha thalassemia Alpha thalassemia Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. Description Alpha thalassemia is a blood disorder that reduces the production ...

  3. Elevated levels of serum alpha(2) macroglobulin in wild black bears during hibernation.

    Science.gov (United States)

    Sheikh, Ashfaq M; Chauhan, Ved; Tsiouris, John A; Mehta, Pankaj D; Burguess, Kelcey; Fenko, Michael D; Spivack, Warren; Vaughan, Michael; Malik, Mazhar

    2003-10-01

    Bear serum alpha(2) macroglobulin (alpha(2)M) was purified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and partially characterized by tryptic digestion of alpha(2)M and analysis of the peptides by peptide mass fingerprinting. The molecular weight of bear serum alpha(2)M was 181 kDa, same as for human serum alpha(2)M, on SDS-PAGE. However, the MALDI mass spectrum of the tryptic digested bear serum alpha(2)M showed that it is different from human alpha(2)M or other data bank proteins. Liquid chromatography (LC)/mass spectrometry (MS)/MS of the proteolytic products of bear serum alpha(2)M showed eight peptides that had similarities to human alpha(2)M suggesting that the protein of interest was indeed alpha(2)M of bear. The polyclonal antibody against bear serum alpha(2)M recognized only one protein from the western blot of bear serum proteins. It also recognized human alpha(2)M. The levels of serum alpha(2)M were significantly increased during hibernating state as compared to active state of bears indicating its protective role from the consequences of the metabolic depression during hibernation.

  4. Combustion of hythane diluted with CO2

    Directory of Open Access Journals (Sweden)

    Hraiech Ibtissem

    2015-01-01

    Full Text Available With increasing concern about energy shortage and environmental protection, improving engine fuel economy and reducing exhaust emissions have become major research topics in combustion and engine development. Hythane (a blend of hydrogen H2 and natural gas NG has generated a significant interest as an alternative fuel for the future. This paper describes an experimental study of the effects of CO2 addition on the stability of a turbulent jet diffusion NG-H2 flame. The mole fraction of hydrogen (% H2 in NG-H2 mixture was varied from 0% to 50%. The equivalence ratio of the hythane/CO2/air mixture was kept at stoichiometry. The results show that the lift-off height increases with the addition of CO2 at various % H2 content in hythane. However, we observe that with 20% H2, we can obtain a stable flame diluted with 40% CO2, while for 0% H2, the flame is blown out above 20% CO2. This means that the limits of flame blowing out are pushed with the additions of H2. Moreover, the results show that for %H2 content in NG-H2 fuel up to 10%, the addition of CO2 could produce lifted flame if the % CO2 is low. At higher % CO2 dilution, flame would remain attached until blow-out. This is mainly due to the fact that the dilution leads to ejection velocities very high but reactivity of the mixture does not change so the flame tends to stretch.

  5. Subcloning Dt40 by limiting dilution.

    Science.gov (United States)

    Buerstedde, Jean-Marie

    2006-01-01

    Subcloning by limited dilution can be used to derive clonally related cell populations from a heterogeneous DT40 cell culture. For example, if one suspects that a drug resistant population may represent the progeny of more than one transfectant, the protocol can be used to isolate genetically homogeneous mutant clones. Other uses are the excision of floxed DNA sequences after Cre recombinase expression or fluctuation analysis to determine mutation rates (see Protocols 'Excision of floxed-DNA sequences by transient induction of Mer-Cre-Mer' and 'Analysis of sIgM expression by FACS').

  6. Confluence Model or Resource Dilution Hypothesis?

    DEFF Research Database (Denmark)

    Jæger, Mads

    Studies on family background often explain the negative effect of sibship size on educational attainment by one of two theories: the Confluence Model (CM) or the Resource Dilution Hypothesis (RDH). However, as both theories – for substantively different reasons – predict that sibship size should...... to identify a unique RDH effect on educational attainment. Using sibling data from the Wisconsin Longitudinal Study (WLS) and a random effect Instrumental Variable model, I find that in addition to having a negative effect on cognitive ability, sibship size also has a strong negative effect on educational...

  7. Determining Some Parameters Of Uranium Material By GAMMA Spectrometry Using Intrinsic Efficiency Calibration

    International Nuclear Information System (INIS)

    Le Tuan Anh; Bui Minh Hue; Bui Van Loat; Nguyen Cong Tam

    2011-01-01

    Abundance and age of uranium material are two significant parameters. Traditionally, they are determined by alpha spectrometry and mass-spectrometry, which are destructive methods. In this report, we exhibit the result of abundance and age, which were determined by gamma-spectrometry using intrinsic efficiency calibration. This is a nondestructive method without using standard source or any reference samples, and applicable to material of any geometrical shape. The result obtained is in good agreement with the results obtained by other authors. (author)

  8. Rapid method for the sequential measurement of isotopes of Am and Pu in liquid matrices by alpha spectrometry; Método rápido para la medida secuencial de isótopos de Am y Pu en matrices líquidas por espectrometría alfa

    Energy Technology Data Exchange (ETDEWEB)

    Mantero Cabrera, J.

    2014-07-01

    : In radiological emergencies it's necessary a fast response from the laboratories in the quantification of certain radionuclides, in order to take decisions. In these cases, is the reaction time the key parameter to consider (without neglecting the quality of the measurement). In this work, it is shown a method for aqueous matrices that generates Pu and Am isotopes sources in one single day of work, to be measured subsequently by alpha spectrometry. The developed methodology has been validated through its application to reference samples and also taking part intercom- parison exercises, having in both cases, satisfactory results. This way, we check the validity of this fast method that let us generate in 24 hours (since the sample arrives our laboratory), one measurement with a Minimun Detectable Activity (MDA) of about 0.004Bq/L for Pu and Am isotopes in liquid matrices. [Spanish] En situaciones de emergencia radiológica es muy común la necesidad de dar una respuesta rápida por parte de los laboratorios en la cuantificación de ciertos radionucleidos, de cara a la toma de decisiones. En estos casos, el tiempo de reacción es una variable fundamental a considerar (aunque obviamente sin dejar de lado la calidad en el resultado de la medida). En este trabajo se presenta un método para matrices acuosas que permite generar en una única jornada de trabajo, las fuentes de medida necesarias en la detección de isótopos de Pu y Am para ser medidas con posterioridad por espectrometría alfa. La metodología puesta a punto ha sido validada mediante su aplicación a muestras de referencia y mediante la participación en ejercicios de intercomparación, en ambos casos, con resultados satisfactorios. Queda así demostrada la validez de este método rápido que nos permite generar en 24 horas desde la recepción de la muestra, una medida en nuestros sistemas con una Actividad Mínima Detectable (AMD) de 0.004 Bq/L tanto para isótopos de Pu (238Pu, 239+240Pu) como de

  9. Estimative of dilution factor for radioactive liquid effluents employing the H-3 and Cs-137 radiotracers present as pollutant

    International Nuclear Information System (INIS)

    Nisti, Marcelo Bessa; Santos, Adir Janete Godoy dos

    2011-01-01

    It was estimated the dilution factor for liquid effluents at the discharge points of the IPEN, Sao Paulo, Brazil, employing as radiotracers the radioisotope routinely liberated for the sewage of 'Cidade Universitaria Armando de Salles Oliveira' - CUASO 3 H and 137 Cs, not generating either monetary or environmental cost associated to the estimation. The 137 Cs was determined by gamma spectrometry and the 3 H was determined liquid phase scintillation. The results showed that the dilution factor varied according to the employed radiotracer in a crescent order of 3 H and 137 Cs according to the characteristics of each element. The average of dilution factors obtained at the first and second liberation day were 4.3 and 7.4 respectively for the 3 H and 6.2 and 13.9 for the 137 Cs. The ratio of dilution factors of calculated 3 H and 137 Cs were coherent with the ratio verified at the twelve hydrometers distributed by the IPEN campus. The dilution factors were estimated in operational and laboratory study, in a single controlled discharge of the TR1 tank

  10. Alpha Thalassemia (For Parents)

    Science.gov (United States)

    ... the body has a problem producing alpha globin Beta thalassemia : when the body has a problem producing beta ... Transfusion Blood Test: Hemoglobin Electrophoresis Sickle Cell Disease Beta Thalassemia Blood All About Genetics Prenatal Genetic Counseling Genetic ...

  11. Neutron scattering study of dilute supercritical solutions

    International Nuclear Information System (INIS)

    Cochran, H.D.; Wignall, G.D.; Shah, V.M.; Londono, J.D.; Bienkowski, P.R.

    1994-01-01

    Dilute solutions in supercritical solvents exhibit interesting microstructures that are related to their dramatic macroscopic behavior. In typical attractive solutions, solutes are believed to be surrounded by clusters of solvent molecules, and solute molecules are believed to congregate in the vicinity of one another. Repulsive solutions, on the other hand, exhibit a local region of reduced solvent density around the solute with solute-solute congregation. Such microstructures influence solubility, partial molar volume, reaction kinetics, and many other properties. We have undertaken to observe these interesting microstructures directly by neutron scattering experiments on dilute noble gas systems including Ar. The three partial structure factors for such systems and the corresponding pair correlation functions can be determined by using the isotope substitution technique. The systems studied are uniquely suited for our objectives because of the large coherent neutron scattering length of the isotope 36 Ar and because of the accurate potential energy functions that are available for use in molecular simulations and theoretical calculations to be compared with the scattering results. We will describe our experiment, the unique apparatus we have built for it, and the neutron scattering results from our initial allocations of beam time. We will also describe planned scattering experiments to follow those with noble gases, including study of long-chain molecules in supercritical solvents. Such studies will involve hydrocarbon mixtures with and without deuteration to provide contrast

  12. Capsize of polarization in dilute photonic crystals.

    Science.gov (United States)

    Gevorkian, Zhyrair; Hakhoumian, Arsen; Gasparian, Vladimir; Cuevas, Emilio

    2017-11-29

    We investigate, experimentally and theoretically, polarization rotation effects in dilute photonic crystals with transverse permittivity inhomogeneity perpendicular to the traveling direction of waves. A capsize, namely a drastic change of polarization to the perpendicular direction is observed in a one-dimensional photonic crystal in the frequency range 10 ÷ 140 GHz. To gain more insights into the rotational mechanism, we have developed a theoretical model of dilute photonic crystal, based on Maxwell's equations with a spatially dependent two dimensional inhomogeneous dielectric permittivity. We show that the polarization's rotation can be explained by an optical splitting parameter appearing naturally in Maxwell's equations for magnetic or electric fields components. This parameter is an optical analogous of Rashba like spin-orbit interaction parameter present in quantum waves, introduces a correction to the band structure of the two-dimensional Bloch states, creates the dynamical phase shift between the waves propagating in the orthogonal directions and finally leads to capsizing of the initial polarization. Excellent agreement between theory and experiment is found.

  13. ALPHA-2: the sequel

    CERN Multimedia

    Katarina Anthony

    2012-01-01

    While many experiments are methodically planning for intense works over the long shutdown, there is one experiment that is already working at full steam: ALPHA-2. Its final components arrived last month and will completely replace the previous ALPHA set-up. Unlike its predecessor, this next generation experiment has been specifically designed to measure the properties of antimatter.   The ALPHA team lower the new superconducting solenoid magnet into place. The ALPHA collaboration is working at full speed to complete the ALPHA-2 set-up for mid-November – this will give them a few weeks of running before the AD shutdown on 17 December. “We really want to get some experience with this device this year so that, if we need to make any changes, we will have time during the long shutdown in which to make them,” says Jeffrey Hangst, ALPHA spokesperson. “Rather than starting the 2014 run in the commissioning stage, we will be up and running from the get go.&...

  14. Expression of triplicated and quadruplicated alpha globin genes in sheep.

    Science.gov (United States)

    Vestri, R; Pieragostini, E; Yang, F; di Gregorio, P; Rando, A; Masina, P

    1991-01-01

    In the sheep alpha alpha alpha globin gene haplotype, the three genes display from the 5' to the 3' end the percentage efficiencies of about 30:14:6, as indicated by the amounts of the three types of alpha chain produced in the alpha alpha alpha/alpha alpha alpha homozygotes. The 3' gene in the alpha alpha alpha alpha haplotype appears to have an efficiency around 1%, as suggested by analysis of one quadruple alpha homozygote. Moreover, the total outputs of the alpha alpha alpha as well as of the alpha alpha alpha alpha haplotypes do not substantially differ from that of the common alpha alpha haplotype.

  15. Acute moderate elevation of TNF-{alpha} does not affect systemic and skeletal muscle protein turnover in healthy humans

    DEFF Research Database (Denmark)

    Petersen, Anne Marie; Plomgaard, Peter; Fischer, Christian P

    2009-01-01

    Context: Skeletal muscle wasting has been associated with elevations in circulating inflammatory cytokines, in particular TNF-alpha. Objective: In this study, we investigated whether TNF-alpha affects human systemic and skeletal muscle protein turnover, via a 4 hours recombinant human TNF......-alpha infusion (rhTNF-alpha). We hypothesize that TNF-alpha increases human muscle protein breakdown and/or inhibit synthesis. Subjects and Methods: Using a randomized controlled, crossover design post-absorptive healthy young males (n=8) were studied 2 hours under basal conditions followed by 4 hours infusion...... of either rhTNF-alpha (700 ng.m(-2).h(-1)) or 20% human albumin (Control) which was the vehicle of rhTNF-alpha. Systemic and skeletal muscle protein turnover were estimated by a combination of tracer dilution methodology (primed continuous infusion of L-[ring-(2)H5]phenylalanine and L-[(15)N...

  16. Retrieval properties of diluted attractor neural networks

    Science.gov (United States)

    Rodrigues Neto, C.; Fontanari, J. F.

    1996-06-01

    We investigate the dependence of the retrieval properties of the pseudo-inverse and optimal attractor neural networks on the fraction of stored patterns 0305-4470/29/12/012/img1, the temperature T and the margin parameter 0305-4470/29/12/012/img2. Phase diagrams in the full space of parameters are presented in the regime of extreme dilution, i.e. when the connectivity C satisfies the condition 0305-4470/29/12/012/img3, where N is the number of neurons. Furthermore, we study analytically the neighbourhood of a stored pattern for both models by calculating the average fraction of unstable sites 0305-4470/29/12/012/img4 in a pattern that differs by d sites from a given stored pattern. This analysis may shed light on the properties of the basins of attraction of the stored patterns.

  17. Critical exponents for diluted resistor networks.

    Science.gov (United States)

    Stenull, O; Janssen, H K; Oerding, K

    1999-05-01

    An approach by Stephen [Phys. Rev. B 17, 4444 (1978)] is used to investigate the critical properties of randomly diluted resistor networks near the percolation threshold by means of renormalized field theory. We reformulate an existing field theory by Harris and Lubensky [Phys. Rev. B 35, 6964 (1987)]. By a decomposition of the principal Feynman diagrams, we obtain diagrams which again can be interpreted as resistor networks. This interpretation provides for an alternative way of evaluating the Feynman diagrams for random resistor networks. We calculate the resistance crossover exponent phi up to second order in epsilon=6-d, where d is the spatial dimension. Our result phi=1+epsilon/42+4epsilon(2)/3087 verifies a previous calculation by Lubensky and Wang, which itself was based on the Potts-model formulation of the random resistor network.

  18. Mechanisms of urine concentration and dilution (1961)

    International Nuclear Information System (INIS)

    Morel, F.; Guinnebault, M.

    1961-01-01

    This paper is devoted to the analysis of a problem in the field of renal physiology which has shown many new developments during the course of the last few years. The following are treated successively: a) the data obtained from measurements of free water clearance and their interpretation; b) the data provided by nephron morphology and the comparative anatomy of the kidney ; c) the data relative to the existence of an intrarenal osmotic gradient; d) the principle of concentration multiplication by a counter current technique; e) the present day theory of counter current concentration of urine, and f) the physiological check on dilution and concentration mechanisms in urine. Lastly, the advantages of the modern theory and the unknown factors which remain are discussed. (authors) [fr

  19. Disorder effects in diluted ferromagnetic semiconductors

    Science.gov (United States)

    Bouzerar, G.; Kudrnovský, J.; Bruno, P.

    2003-11-01

    Carrier induced ferromagnetism in diluted III-V semiconductor (DMS) is analyzed within a two-step approach. First, within a single site coherent-potential approximation formalism, we calculate the element resolved averaged Green’s function of the itinerant carrier. Then using a generalized RKKY formula we evaluate the Mn-Mn long-range exchange integrals and the Curie temperature as a function of the exchange parameter, magnetic impurity concentration, and carrier density. The effect of a proper treatment of the disorder which includes all single-site multiple scattering appears to play a crucial role. The standard RKKY calculation which neglects disorder, strongly underestimates the Curie temperature and is inappropriate to describe magnetism in DMS. It is also shown that an antiferromagnetic exchange favors higher Curie temperature.

  20. Calculation of inherent boron dilution scenarios

    International Nuclear Information System (INIS)

    Kereszturi, A.; Toth, E.L.; Telbisz, M.; Trosztel, I.

    1999-01-01

    Two inherent boron dilution scenarios have been investigated in the frame of the PH2.08 PHARE project supported by the EC[1]. The Small Break LOCA (SBLOCA) initiating event was investigated by the SMABRE[2] and ATHLET[3] codes, while the SMATRA[4] code was used for the study of an ATWS initiating event. The results show that in case of SBLOCA slug formation is possible if the operator starts to cool down the secondary loop but the slug does not enter the core because it is removed by the Low Pressure Safety Injection. In case of ATWS, it was concluded that the maximum void fraction in the hot leg remained below 95% and that there was sufficient water in the two-phase flow to prevent formation of un borated slugs. Furthermore at the time the condensation of steam was already impossible in the steam generators because of drying out. (Authors)

  1. Water Metabolism of Walruses by Isotope Dilution

    DEFF Research Database (Denmark)

    Acquarone, M.; Born, E. W.; Chwalibog, A.

    was sampled via an epidural catheter, at regular intervals, for up to seven hours after the initial enrichment to assess isotope equilibration in the body water pools. Five individuals returned to the haul-out after feeding trips of varying duration (158±86 hr, 44-287 hr) where they were immobilized again......In August 2000, the hydrogen isotope dilution method was used on 7 adult male Atlantic walruses (Odobenus rosmarus rosmarus) (weight: 1197±148 kg, mean±SD, range 1013-1508 kg) at a terrestrial haul-out in Northeastern Greenland to determine their body water pool sizes and body water turnover rates....... During immobilization by use of etorphine HCl (reversed with diprenorphine HCl), a first blood sample was taken to measure background isotope levels. The animals were then enriched with deuterium oxide by infusion into the epidural vein. During recovery, while the animals were still on the beach, blood...

  2. Monte Carlo alpha calculation

    Energy Technology Data Exchange (ETDEWEB)

    Brockway, D.; Soran, P.; Whalen, P.

    1985-01-01

    A Monte Carlo algorithm to efficiently calculate static alpha eigenvalues, N = ne/sup ..cap alpha..t/, for supercritical systems has been developed and tested. A direct Monte Carlo approach to calculating a static alpha is to simply follow the buildup in time of neutrons in a supercritical system and evaluate the logarithmic derivative of the neutron population with respect to time. This procedure is expensive, and the solution is very noisy and almost useless for a system near critical. The modified approach is to convert the time-dependent problem to a static ..cap alpha../sup -/eigenvalue problem and regress ..cap alpha.. on solutions of a/sup -/ k/sup -/eigenvalue problem. In practice, this procedure is much more efficient than the direct calculation, and produces much more accurate results. Because the Monte Carlo codes are intrinsically three-dimensional and use elaborate continuous-energy cross sections, this technique is now used as a standard for evaluating other calculational techniques in odd geometries or with group cross sections.

  3. Magnetic Properties and Oxygen Defects of Dilute Metal Doped Tin Oxide Based Semiconductor

    Directory of Open Access Journals (Sweden)

    Kiyoshi Nomura

    2015-12-01

    Full Text Available Chemical and magnetic states of iron doped tin oxide (SnO2 as a diluted magnetic semiconductor (DMS at room temperature have been investigated using 57Fe Mössbauer spectrometry, XRD and magnetometery. The influence of the doping conditions of SnO2 with iron on the generation of oxygen defects was reviewed and discussed on the basis of ab initio calculations. The magnetic properties depended on preparation conditions, such as thermal decomposition and sol-gel processing as well as 57Fe and super-dilute 57Mn implantation. It was shown that Sb codoping in Fe doped SnO2 increases the saturation magnetization. Doping of Fe(Sb-SnO2 with nonmagnetic Zn ions up to 7 % also increases the magnetization although there is no precipitation of crystalline magnetic phases. The co-doping of two transition metal ions (Fe-Co, Fe-Mn, Fe-Ni and Fe-V in SnO2 matrix enhanced the magnetization as compared with that of single metal ion doped samples. It is suggested from different valence states of doped metal ions that double exchange interactions occur through or near the oxygen vacancies in SnO2. The SnO2 doped with dilute 57Fe may show the intrinsic and/or extrinsic DMS properties. Oxygen vacancies play an important role in the intrinsic DMS. The intrinsic nature of DMS is supported by both, experimental results and ab initio calculations. The long range interactions between diluted magnetic ions are considered to occur through electrons produced by oxygen vacancies or electrons induced by Sb5+ doping.

  4. Determination of cortisol in two BCR reference sera by isotope dilution gas chromatography-mass spectrometry

    NARCIS (Netherlands)

    Derks; H.J.G.M.; Freudenthal; J.; Heiningen; A.van; Gramberg; L.G.; Klaasen; R.

    1984-01-01

    In dit rapport wordt een analytische methode voor de juiste en preciese bepaling van cortisol in humaan serum en zijn toepassing bij de certificatie van twee gevriesdroogde referentiesera van de BCR beschreven. De methode is gebaseerd op isotoopverdunnings gaschromatografie-massaspectrometrie

  5. Measurement uncertainty in single, double and triple isotope dilution mass spectrometry.

    Science.gov (United States)

    Vogl, Jochen

    2012-02-15

    Triple IDMS has been applied for the first time to the quantification of element concentrations. It has been compared with single and double IDMS obtained on the same sample set in order to evaluate the advantages and disadvantages of triple IDMS over single and double IDMS as an analytical reference procedure. The measurement results of single, double and triple IDMS are indistinguishable, considering rounding due to the individual measurement uncertainties. As expected, the relative expanded uncertainties (k = 2) achieved with double IDMS (0.08%) are dramatically smaller than those obtained with single IDMS (1.4%). Triple IDMS yields the smallest relative expanded uncertainties (k = 2, 0.077%) unfortunately at the expense of a much higher workload. Nevertheless triple IDMS has the huge advantage that the isotope ratio of the spike does not need to be determined. Elements with high memory effects, highly enriched spikes or highest metrological requirements may be typical applications for triple IDMS. Copyright © 2011 John Wiley & Sons, Ltd.

  6. Dilution in a Dense Bottom Jet in Cross Currents

    DEFF Research Database (Denmark)

    Petersen, O.; Larsen, Torben

    1998-01-01

    A 3-dimensional numerical model describing the dilution in the near field around dense vertical jets in a cross flow is formulated and validated against laboratory experiments. The validation shows that the model reproduces the flow pattern well, though the dilution is underestimated by 20......%. The model is applied to a case study where the dilution from two vertical jets at an angle in shallow water is described. It is demonstrated that a 20% increase in dilution is possible. It is concluded that the model may become a valuable tool in diffusor design....

  7. 21 CFR 866.2500 - Microtiter diluting and dispensing device.

    Science.gov (United States)

    2010-04-01

    ... SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2500... a mechanical device intended for medical purposes to dispense or serially dilute very small...

  8. Monte Carlo alpha deposition

    International Nuclear Information System (INIS)

    Talley, T.L.; Evans, F.

    1988-01-01

    Prior work demonstrated the importance of nuclear scattering to fusion product energy deposition in hot plasmas. This suggests careful examination of nuclear physics details in burning plasma simulations. An existing Monte Carlo fast ion transport code is being expanded to be a test bed for this examination. An initial extension, the energy deposition of fast alpha particles in a hot deuterium plasma, is reported. The deposition times and deposition ranges are modified by allowing nuclear scattering. Up to 10% of the initial alpha particle energy is carried to greater ranges and times by the more mobile recoil deuterons. 4 refs., 5 figs., 2 tabs

  9. Buffett’s Alpha

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Kabiller, David; Heje Pedersen, Lasse

    Berkshire Hathaway has realized a Sharpe ratio of 0.76, higher than any other stock or mutual fund with a history of more than 30 years, and Berkshire has a significant alpha to traditional risk factors. However, we find that the alpha becomes insignificant when controlling for exposures to Betting......-Against-Beta and Quality-Minus-Junk factors. Further, we estimate that Buffett’s leverage is about 1.6-to-1 on average. Buffett’s returns appear to be neither luck nor magic, but, rather, reward for the use of leverage combined with a focus on cheap, safe, quality stocks. Decomposing Berkshires’ portfolio into ownership...

  10. In vitro effect of zearalenone and alpha-zearalenol on boar sperm characteristics and acrosome reaction.

    Science.gov (United States)

    Tsakmakidis, I A; Lymberopoulos, A G; Alexopoulos, C; Boscos, C M; Kyriakis, S C

    2006-10-01

    This study was conducted to determine the in vitro effects of three different concentrations (125, 187.5 and 250 microM in diluted semen) of zearalenone (zen) and alpha-zearalenol (alpha-zen) on boar sperm. Semen parameters such as motility, viability and spontaneous acrosome reaction were evaluated. From the results it was shown that both zen and alpha-zen affected the sperm characteristics significantly (p < 0.05), except for alpha-zen at the low concentration which did not decrease the percentage of live reacted spermatozoa significantly. In conclusion, zen and alpha-zen are directly toxic when they affect boar semen in vitro and consequently decrease the fertilization ability of the sperm. The higher the concentration of mycotoxin tested, the greater the decline of sperm parameters noticed. The influence of mycotoxins was found to be time- and dose-dependent.

  11. Maduramicin. alpha. : Characterization of sup 14 C-derived residues in turkey excreta

    Energy Technology Data Exchange (ETDEWEB)

    Stout, S.J.; daCunha, A.R.; Lee, A. (American Cyanamid Co., Princeton, NJ (United States)); Jinn Wu; King, K.G. (XenoBiotic Labs., Inc., Princeton, NJ (United States))

    1991-02-01

    Maduramicin {alpha}, a highly potent polyether ionophore antibiotic for preventing coccidiosis in poultry, is passed predominantly in turkey excreta following oral feeding. Following isolation and purification, the turkey excreta metabolites were characterized primarily by liquid chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry. Maduramicin {alpha} and its metabolites generate a characteristic pair of ions corresponding to (M + NH{sub 4}){sup +} and (M + Na){sup +} which assist in differentiating the metabolites from matrix coextractives. These two ions also fragment differently in tandem mass spectrometry, thus providing structural information for characterizing the nature of unknown metabolites. The primary metabolic pathway of maduramicin {alpha} in the turkey is O-demethylation at one or more of the methoxy groups. Hydroxylation and glucuronide conjugation are minor secondary metabolic processes.

  12. Measurement of isotope abundance variations in nature by gravimetric spiking isotope dilution analysis (GS-IDA).

    Science.gov (United States)

    Chew, Gina; Walczyk, Thomas

    2013-04-02

    Subtle variations in the isotopic composition of elements carry unique information about physical and chemical processes in nature and are now exploited widely in diverse areas of research. Reliable measurement of natural isotope abundance variations is among the biggest challenges in inorganic mass spectrometry as they are highly sensitive to methodological bias. For decades, double spiking of the sample with a mix of two stable isotopes has been considered the reference technique for measuring such variations both by multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) and multicollector-thermal ionization mass spectrometry (MC-TIMS). However, this technique can only be applied to elements having at least four stable isotopes. Here we present a novel approach that requires measurement of three isotope signals only and which is more robust than the conventional double spiking technique. This became possible by gravimetric mixing of the sample with an isotopic spike in different proportions and by applying principles of isotope dilution for data analysis (GS-IDA). The potential and principle use of the technique is demonstrated for Mg in human urine using MC-TIMS for isotopic analysis. Mg is an element inaccessible to double spiking methods as it consists of three stable isotopes only and shows great potential for metabolically induced isotope effects waiting to be explored.

  13. Dilute Surfactant Methods for Carbonate Formations

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2006-02-01

    There are many fractured carbonate reservoirs in US (and the world) with light oil. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). The process of using dilute anionic surfactants in alkaline solutions has been investigated in this work for oil recovery from fractured oil-wet carbonate reservoirs both experimentally and numerically. This process is a surfactant-aided gravity drainage where surfactant diffuses into the matrix, lowers IFT and contact angle, which decrease capillary pressure and increase oil relative permeability enabling gravity to drain the oil up. Anionic surfactants have been identified which at dilute concentration of 0.05 wt% and optimal salinity can lower the interfacial tension and change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil. The force of adhesion in AFM of oil-wet regions changes after anionic surfactant treatment to values similar to those of water-wet regions. The AFM topography images showed that the oil-wetting material was removed from the surface by the anionic surfactant treatment. Adsorption studies indicate that the extent of adsorption for anionic surfactants on calcite minerals decreases with increase in pH and with decrease in salinity. Surfactant adsorption can be minimized in the presence of Na{sub 2}CO{sub 3}. Laboratory-scale surfactant brine imbibition experiments give high oil recovery (20-42% OOIP in 50 days; up to 60% in 200 days) for initially oil-wet cores through wettability alteration and IFT reduction. Small (<10%) initial gas saturation does not affect significantly the rate of oil recovery in the imbibition process, but larger gas saturation decreases the oil recovery rate. As the core permeability decreases, the rate of oil recovery reduces

  14. Case Study - Alpha

    Directory of Open Access Journals (Sweden)

    Stephen Leybourne

    2016-11-01

    Full Text Available This case study was developed from an actual scenario by Dr. Steve Leybourne of Boston University.  The case documents the historical evolution of an organization, and has been used successfully in courses dealing with organizational and cultural change, and the utilization of ‘soft skills’ in project-based management. This is a short case, ideal for classroom use and discussion.  The issues are easily accessible to students, and there is a single wide ranging question that allows for the inclusion of many issues surrounding strategic decision-making, and behavioural and cultural change. Alpha was one of the earlier companies in the USA to invest in large, edge-of-town superstores, with plentiful free vehicle parking, selling food and related household products. Alpha was created in the 1950s as a subsidiary of a major publicly quoted retail group.  It started business by opening a string of very large discount stores in converted industrial and warehouse premises in the south of the United States. In the early days shoppers were offered a limited range of very competitively priced products. When Alpha went public in 1981 it was the fourth largest food retailer in the US, selling an ever-widening range of food and non-food products.  Its success continued to be based on high volume, low margins and good value for money, under the slogan of ‘Alpha Price.’

  15. Alpha-mannosidosis

    DEFF Research Database (Denmark)

    Borgwardt, Line; Stensland, Hilde Monica Frostad Riise; Olsen, Klaus Juul

    2015-01-01

    of the three subgroups of genotype/subcellular localisation and the clinical and biochemical data were done to investigate the potential relationship between genotype and phenotype in alpha-mannosidosis. Statistical analyses were performed using the SPSS software. Analyses of covariance were performed...

  16. Improved Isotopic Measurement of Plutonium by Thermal Ionization Mass Spectrometry

    International Nuclear Information System (INIS)

    Shick, C. Jr.

    2002-01-01

    Thermal ionization mass spectrometry (TIMS) is accepted widely as the benchmark method for precise and accurate isotopic determination of plutonium. TIMS is one of the few analytical methods capable of determining Pu in bioassay samples at the level required for detecting a 50 yr committed dose of 100 mRem resulting from an inhalation exposure to highly insoluble forms of Pu. Typically, Pu is measured in bioassay samples by radiochemical separation, electrodeposition onto a planchet, and radiometric determination by alpha spectrometry. If, based on the alpha spectrometry results, a sample is deemed to need a more sensitive analysis (i.e. suspected uptake, borderline alpha spectrometry positive for Pu uptake, etc.), then the sample is prepared for analysis by TIMS. Part of the development process for establishing a program to determine Pu in bioassay samples by TIMS at the Savannah River Site involved a careful evaluation of the Pu blank value in the reagents used for sample preparation and in urine blanks. This exercise allowed for the evaluation of the newly developed radiochemical separation procedure, the resin bead loading procedure, and the detection limits of the thermal ionization mass spectrometer

  17. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2003-07-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate wettability. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting adsorption, phase behavior and wettability studies.

  18. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2003-07-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior, interfacial tension (IFT) and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil-wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate-wet for many surfactants and water-wet for one surfactant. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting core adsorption, phase behavior, wettability and mobilization studies.

  19. Dilute antiferromagnetism in magnetically doped phosphorene

    Directory of Open Access Journals (Sweden)

    Andrew Allerdt

    2017-11-01

    Full Text Available We study the competition between Kondo physics and indirect exchange on monolayer black phos-phorous using a realistic description of the band structure in combination with the density matrixrenormalization group (DMRG method. The Hamiltonian is reduced to a one-dimensional problemvia an exact canonical transformation that makes it amenable to DMRG calculations, yielding exactresults that fully incorporate the many-body physics. We find that a perturbative description of theproblem is not appropriate and cannot account for the slow decay of the correlations and the completelack of ferromagnetism. In addition, at some particular distances, the impurities decouple formingtheir own independent Kondo states. This can be predicted from the nodes of the Lindhard function.Our results indicate a possible route toward realizing dilute anti-ferromagnetism in phosphorene. Received: 19 September 2017, Accepted: 12 October 2017; Edited by: K. Hallberg; DOI: http://dx.doi.org/10.4279/PIP.090008 Cite as: A Allerdt, A E Feiguin, Papers in Physics 9, 090008 (2017

  20. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2003-01-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have acquired field oil and core samples and field brine compositions from Marathon. We have conducted preliminary adsorption and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Receding contact angles increase with surfactant adsorption. Plans for the next quarter include conducting adsorption, phase behavior and wettability studies.

  1. Dilution in Transition Zone between Rising Plumes and Surface Plumes

    DEFF Research Database (Denmark)

    Larsen, Torben

    2004-01-01

    The papers presents some physical experiments with the dilution of sea outfall plumes with emphasize on the transition zone where the relative fast flowing vertical plume turns to a horizontal surface plume following the slow sea surface currents. The experiments show that a considerable dilution...

  2. The dilute random field Ising model by finite cluster approximation

    International Nuclear Information System (INIS)

    Benyoussef, A.; Saber, M.

    1987-09-01

    Using the finite cluster approximation, phase diagrams of bond and site diluted three-dimensional simple cubic Ising models with a random field have been determined. The resulting phase diagrams have the same general features for both bond and site dilution. (author). 7 refs, 4 figs

  3. Nonthermal plasma assisted photocatalytic oxidation of dilute benzene

    Indian Academy of Sciences (India)

    to utilize the UV light for photocatalytic decomposition of chlorinated VOCs.23. Benzene, a commonly used industrial solvent, whose abatement under dilute concentrations (<1000 ppm) may not be economical by conventional techniques. The present study was aimed at the total oxidation of dilute benzene in a DBD reactor.

  4. Behaviour of humic-bentonite aggregates in diluted suspensions ...

    African Journals Online (AJOL)

    Formation and disaggregation of micron-size aggregates in a diluted suspension made up of HSs and bentonite (B) were studied by tracing distribution of aggregate sizes and their counts in freshly prepared and aged suspensions, and at high (10 000) and low (1.0) [HS]/[B] ratios. Diluted HSB suspensions are unstable ...

  5. Near-wall molecular ordering of dilute ionic liquids

    NARCIS (Netherlands)

    Jitvisate, Monchai; Seddon, James Richard Thorley

    2017-01-01

    The interfacial behavior of ionic liquids promises tunable lubrication as well as playing an integral role in ion diffusion for electron transfer. Diluting the ionic liquids optimizes bulk parameters, such as electric conductivity, and one would expect dilution to disrupt the near-wall molecular

  6. Enhancement of surface magnetism due to bulk bond dilution

    International Nuclear Information System (INIS)

    Tsallis, C.; Sarmento, E.F.; Albuquerque, E.L. de

    1985-01-01

    Within a renormalization group scheme, the phase diagram of a semi-infinite simple cubic Ising ferromagnet is discussed, with arbitrary surface and bulk coupling constants, and including possible dilution of the bulk bonds. It is obtained that dilution makes easier the appearance of surface magnetism in the absence of bulk magnetism. (Author) [pt

  7. Effect of dietary dilution of energy and nutrients during different ...

    African Journals Online (AJOL)

    A completely randomized design was conducted to evaluate the effect of dietary dilution of energy and nutrients during different growing periods on compensatory growth of Ross broilers. Four replicant pens were assigned per seven treatments. Chicks in each treatment received concentrated and diluted diets in different ...

  8. Study of oxygen diluted silane plasmas applied for the deposition of silicium oxyde

    International Nuclear Information System (INIS)

    Magni, D.

    2001-09-01

    Plasma enhanced chemical vapour deposition of thin films such as silicon dioxide is used in many applications such as the insulator production in semiconductor technology or anticorrosion coating in packaging industry as a substitute for aluminium which is less ecological. Oxygen diluted silane plasmas are often utilized to produce SiO 2 film, but the tendency is to work with organosilicon precursors such as HMDSO (hexamethyldisiloxane ) described as non-toxic and requiring less stringent safety and costly installation. In this study, the species in gaseous phase and the powder produced in oxygen-diluted HMDSO plasmas were experimentally characterized in a radiofrequency (RF) capacitively-coupled reactor at 13.56 MHz. Some aspects of plasma enhanced deposition of SiO 2 were studied in a RF magnetron reactor . The gaseous phase of the oxygen-diluted plasmas were studied by infrared absorption spectroscopy and mass spectrometry .The complementarity of these diagnostics allowed to show that the dominant species in gaseous phase come from the homogeneous reaction between oxygen and the radical CH x (with x 1,2 and 3), abundantly produced in the plasma. Two principal pathways were shown to occur. A first way leads to hydrocarbon formation such as methane (CH 4 ) and acetylene (C 2 H 2 ), whose partial pressures are close to 2 %. A second way leads to the formation of molecules from the combustion of CH x , such as formaldehyde (CH 2 O), formic acid (CH 2 O 2 ), carbon monoxide (CO), carbon dioxide (CO 2 ) and water. Moreover it is shown that the CO 2 results from a heterogeneous reaction between the carbon on the surfaces and the oxygen coming from the plasma. At low dilution conditions, the partial pressures of CO and CO 2 were estimated at 25 and 10 % of the total pressure respectively. In argon or helium diluted HMDSO plasmas, methane, acetylene and hydrogen are the main stable molecules produced in the gaseous phase. Particle formation in oxygen-diluted HMDSO

  9. Alpha cluster states in light nuclei populated through the (6Li,d) reaction

    Energy Technology Data Exchange (ETDEWEB)

    Borello-Lewin, Thereza; Rodrigues, M.R.D.; Horodynski-Matsushigue, L.B.; Duarte, J.L.M.; Rodrigues, C.L.; Souza, M.A. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica; Cunsolo, A.; Cappuzzello, F. [Universita di Catania (Italy). Istituto Nazionale di Fisica Nucleare. Lab. Nazionali del Sud; Ukita, Gilberto Mitsuo [Universidade de Santo Amaro (UNISA), Sao Paulo, SP (Brazil). Fac. de Psicologia

    2011-07-01

    Full text: The alpha cluster correlation is an important concept in the nuclear physics of light nuclei. The main purpose of the research program in progress is the investigation of the alpha clustering phenomenon in (x{alpha}) and(x{alpha}+{nu}) nuclei through the ({sup 6}Li,d) alpha transfer reaction. In fact, there is scarce experimental information on the subject, in particular associated with resonant states predicted near (x{alpha}) and (x{alpha}+{nu}) thresholds. Measurements of the {sup 12},{sup 13}C({sup 6}Li,d) {sup 16},{sup 17}O reactions, at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique. The work is under way and an experimental energy resolution of 30 keV was obtained. Near the (4{alpha}) breakup threshold in {sup 16}O, three narrow alpha resonances, not previously measured, were detected, revealing important {alpha} + {sup 12}C(G.S.) components. One of these resonances corresponds to the known 0{sup +} state at 15.1 MeV[5] of excitation that has probably, according to Funaki et al., the gas like configuration of the 4{alpha} condensate state, with a very dilute density and a large component of {alpha} + {sup 12}C(Hoyle) configuration. As was already mentioned, our experimental information points to the necessity of including the {alpha} + {sup 12}C(G.S.) component in the wave function. (author)

  10. Efficacy comparison between simple mixed-dilution and simple mid-dilution on-line hemodiafiltration techniques: a crossover study.

    Science.gov (United States)

    Susantitaphong, Paweena; Tiranathanagul, Khajohn; Katavetin, Pisut; Hanwiwatwong, Orawadee; Wittayalertpanya, Supeecha; Praditpornsilpa, Kearkiat; Tungsanga, Kriang; Eiam-Ong, Somchai

    2012-12-01

    Mid-dilution and mixed-dilution on-line hemodiafiltration (OL-HDF) techniques are innovated to overcome the limitations of two standard techniques including predilution and postdilution. Unfortunately, the head-to-head comparisons between these two novel techniques in the same study are still limited. Moreover, the original mid-dilution and mixed-dilution OL-HDF need special dialyzers and special machines. In the present study, simple mid-dilution and simple mixed-dilution OL-HDF were settled with the aim for clinical use in general hemodialysis (HD) centers. The efficacies of uremic toxins removal between both modalities were measured and compared. This prospective randomized crossover study was conducted on 12 stable HD patients undergoing simple mixed-dilution and simple mid-dilution OL-HDF techniques. HD prescriptions were similar in both techniques. The dialysis efficacies were determined by calculating small- (urea, creatinine, and phosphate) and middle-molecule (beta-2 microglobulin [β2M]) removal. Moreover, potential complications such as high transmembrane pressure (TMP) and protein loss were also observed. Simple mixed-dilution OL-HDF provided significantly greater clearances of urea, creatinine, and β2M when compared with the simple mid-dilution OL-HDF techniques. Phosphate clearances in both techniques were comparable. In addition, TMP and dialysate albumin loss were not different. There were no intradialytic complications in both techniques. Simple mixed-dilution OL-HDF could provide greater efficacy for small- and middle-molecule clearances and acceptable potential risks, while phosphate removal is comparable. © 2012, Copyright the Authors. Artificial Organs © 2012, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  11. Identification of metabolites in urine and feces from rats dosed with the heterocyclic amine, 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeA alpha C)

    DEFF Research Database (Denmark)

    Frederiksen, H; Frandsen, H

    2004-01-01

    , the in vivo metabolism of MeA alpha C in rats was investigated. Rats were dosed with tritium-labeled MeA alpha C, and urine and feces were collected over 3 days. The metabolites of MeA alpha C were identified by high performance liquid chromatography-mass spectrometry and quantified by liquid scintillation...

  12. Methods of neutron spectrometry

    International Nuclear Information System (INIS)

    Doerschel, B.

    1981-01-01

    The different methods of neutron spectrometry are based on the direct measurement of neutron velocity or on the use of suitable energy-dependent interaction processes. In the latter case the measuring effect of a detector is connected with the searched neutron spectrum by an integral equation. The solution needs suitable unfolding procedures. The most important methods of neutron spectrometry are the time-of-flight method, the crystal spectrometry, the neutron spectrometry by use of elastic collisions with hydrogen nuclei, and neutron spectrometry with the aid of nuclear reactions, especially of the neutron-induced activation. The advantages and disadvantages of these methods are contrasted considering the resolution, the measurable energy range, the sensitivity, and the experimental and computational efforts. (author)

  13. The dilution effect on the extinction of wall diffusion flame

    Directory of Open Access Journals (Sweden)

    Ghiti Nadjib

    2014-12-01

    Full Text Available The dynamic process of the interaction between a turbulent jet diffusion methane flame and a lateral wall was experimentally studied. The evolution of the flame temperature field with the Nitrogen dilution of the methane jet flame was examined. The interaction between the diffusion flame and the lateral wall was investigated for different distance between the wall and the central axes of the jet flame. The dilution is found to play the central role in the flame extinction process. The flame response as the lateral wall approaches from infinity and the increasing of the dilution rate make the flame extinction more rapid than the flame without dilution, when the nitrogen dilution rate increase the flame temperature decrease.

  14. Studies of core response in local boron dilution accidents

    International Nuclear Information System (INIS)

    Siltanen, P.; Antila, M.

    1995-01-01

    During the past few years major attention has been given to analyzing the possibilities and potential consequences of a slug of diluted water entering the core of the WWER-440 reactors in Loviisa. Suitable countermeasures have already been implemented to reduce the probability of external inhomogeneous dilution. Inhomogeneous dilution scenarios with their high reactivity disturbance potential were not included in the original safe analyses. The presentation concentrates on typical dilution scenarios. Results of potential consequences in the core are presented for three typical dilution scenarios for the hot reactor condition. The calculations have been performed using the 3-dimensional dynamic core model HEXTRAN coupled with the circuit model SMABRE. The principles of the new preventive automation recently implemented at Loviisa NPS are also described. (7 refs., 6 figs.)

  15. Measurement of cross sections for alpha-induced reactions on 197Auand thick-target yields for the (alpha,gamma) process on 64Zn and63Cu

    Energy Technology Data Exchange (ETDEWEB)

    Basunia, M.S.; Shugart, H.A.; Smith, A.R.; Norman, E.B.

    2006-08-07

    We have measured the cross sections for the197Au(alpha,gamma)201Tl and 197Au(alpha,2n)199Tl reactions in the 17.9-to 23.9-MeV energy range, and 197Au(alpha,n)200Tl reaction in the 13.4-to 23.9-MeV energy range using an activation technique. Thick-targetyields for the 64Zn(alpha,gamma)68Ge (7- to 14-MeV) and63Cu(alpha,gamma)67Ga (7-MeV) reactions were measured. For allmeasurements, natural elements were bombarded with He+ beams from the88-inch Cyclotron at the Lawrence Berkeley National Laboratory (LBNL).Irradiated samples were counted using a gamma-spectrometry system at LBNLs Low Background Facility. Measured 197Au(alpha,gamma)201Tlcross-sections were compared with the NON-SMOKER theoretical values. Thethick-target yields for the 64Zn(alpha,gamma)68Ge and63Cu(alpha,gamma)67Ga reactions are also compared with the theoreticalyield, calculated numerically using the energy dependent NON-SMOKER crosssection data. In both cases, measured values are found to follow a trendof overlapping the predicted value near the alpha nucleus barrier heightand fall below with a slowly widening difference between them in the subbarrier energy points.

  16. Demystifying AlphaGo Zero as AlphaGo GAN

    OpenAIRE

    Dong, Xiao; Wu, Jiasong; Zhou, Ling

    2017-01-01

    The astonishing success of AlphaGo Zero\\cite{Silver_AlphaGo} invokes a worldwide discussion of the future of our human society with a mixed mood of hope, anxiousness, excitement and fear. We try to dymystify AlphaGo Zero by a qualitative analysis to indicate that AlphaGo Zero can be understood as a specially structured GAN system which is expected to possess an inherent good convergence property. Thus we deduct the success of AlphaGo Zero may not be a sign of a new generation of AI.

  17. $\\alpha$-Representation for QCD

    OpenAIRE

    Tuan, Richard Hong

    1998-01-01

    An $\\alpha$-parameter representation is derived for gauge field theories.It involves, relative to a scalar field theory, only constants and derivatives with respect to the $\\alpha$-parameters. Simple rules are given to obtain the $\\alpha$-representation for a Feynman graph with an arbitrary number of loops in gauge theories in the Feynman gauge.

  18. Alpha Theta Meditation: Phenomenological, neurophysiologic ...

    African Journals Online (AJOL)

    Alpha Theta Meditation: Phenomenological, neurophysiologic, mindfulness, mood, health and sport implications. ... the single alpha theta meditation was associated with elevated alpha and theta activity, as well as decrease in negative mood perceptions, especially with regard to anxiety, sadness and confusion scores.

  19. Dilute Oxygen Combustion Phase I Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, H.M.; Riley, M.F.; Kobayashi, H.

    1997-10-31

    A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NOx) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NOx through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting thermal NOx production. The results of a fundamental and applied research effort on the development of the DOC burner are presented. In addition, the results of a market survey detailing the potential commercial impact of the DOC system are disclosed. The fundamental aspects of the burner development project involved examining the flame characteristics of a natural gas turbulent jet in a high-temperature (~1366 K) oxidant (7-27% O2 vol. wet). Specifically, the mass entrainment rate, the flame lift-off height, the velocity field and major species field of the jet were evaluated as a function of surrounding-gas temperature and composition. The measured entrainment rate of the fuel jet decreased with increasing oxygen content in the surrounding high-temperature oxidant, and was well represented by the d+ scaling correlation found in the literature. The measured flame lift-off height decreased with increasing oxygen content and increasing temperature of the surrounding gas. An increase in surrounding-gas oxygen content and/or temperature inhibited the velocity decay within the jet periphery as a function of axial distance as compared to isothermal turbulent jets. However, the velocity measurements were only broadly represented by the d+ scaling correlation. Several DOC burner configurations were tested in a laboratory-scale furnace at a nominal firing rate of 185 kW (~0.63 MMBtu/h). The flue gas composition was recorded as a function of furnace nitrogen content, furnace temperature, burner geometric arrangement, firing rate, and fuel injection velocity. NOx emissions

  20. Dilute oxygen combustion. Phase I report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-01

    A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NO{sub x}) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NO{sub x} through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting thermal NO{sub x} production. The results of a fundamental and applied research effort on the development of the DOC burner are presented. In addition, the results of a market survey detailing the potential commercial impact of the DOC system are disclosed. The fundamental aspects of the burner development project involved examining the flame characteristics of a natural gas turbulent jet in a high-temperature ({approximately}1366 K) oxidant (7-27% O{sub 2} vol. wet). Specifically, the mass entrainment rate, the flame lift-off height, the velocity field and major species field of the jet were evaluated as a function of surrounding-gas temperature and composition. The measured entrainment rate of the fuel jet decreased with increasing oxygen content in the surrounding high-temperature oxidant, and was well represented by the d{sup +} scaling correlation found in the literature. The measured flame lift-off height decreased with increasing oxygen content and increasing temperature of the surrounding gas. An increase in surrounding-gas oxygen content and/or temperature inhibited the velocity decay within the jet periphery as a function of axial distance as compared to isothermal turbulent jets. However, the velocity measurements were only broadly represented by the d{sup +} scaling correlation. Several DOC burner configurations were tested in a laboratory-scale furnace at a nominal firing rate of 185 kW ({approximately}0.63 MMBtu/h). The flue gas composition was recorded as a function of furnace nitrogen content, furnace temperature, burner geometric

  1. Ionic liquids behave as dilute electrolyte solutions

    Science.gov (United States)

    Gebbie, Matthew A.; Valtiner, Markus; Banquy, Xavier; Fox, Eric T.; Henderson, Wesley A.; Israelachvili, Jacob N.

    2013-01-01

    We combine direct surface force measurements with thermodynamic arguments to demonstrate that pure ionic liquids are expected to behave as dilute weak electrolyte solutions, with typical effective dissociated ion concentrations of less than 0.1% at room temperature. We performed equilibrium force–distance measurements across the common ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2]) using a surface forces apparatus with in situ electrochemical control and quantitatively modeled these measurements using the van der Waals and electrostatic double-layer forces of the Derjaguin–Landau–Verwey–Overbeek theory with an additive repulsive steric (entropic) ion–surface binding force. Our results indicate that ionic liquids screen charged surfaces through the formation of both bound (Stern) and diffuse electric double layers, where the diffuse double layer is comprised of effectively dissociated ionic liquid ions. Additionally, we used the energetics of thermally dissociating ions in a dielectric medium to quantitatively predict the equilibrium for the effective dissociation reaction of [C4mim][NTf2] ions, in excellent agreement with the measured Debye length. Our results clearly demonstrate that, outside of the bound double layer, most of the ions in [C4mim][NTf2] are not effectively dissociated and thus do not contribute to electrostatic screening. We also provide a general, molecular-scale framework for designing ionic liquids with significantly increased dissociated charge densities via judiciously balancing ion pair interactions with bulk dielectric properties. Our results clear up several inconsistencies that have hampered scientific progress in this important area and guide the rational design of unique, high–free-ion density ionic liquids and ionic liquid blends. PMID:23716690

  2. Calculation of Weighted Geometric Dilution of Precision

    Directory of Open Access Journals (Sweden)

    Chien-Sheng Chen

    2013-01-01

    Full Text Available To achieve high accuracy in wireless positioning systems, both accurate measurements and good geometric relationship between the mobile device and the measurement units are required. Geometric dilution of precision (GDOP is widely used as a criterion for selecting measurement units, since it represents the geometric effect on the relationship between measurement error and positioning determination error. In the calculation of GDOP value, the maximum volume method does not necessarily guarantee the selection of the optimal four measurement units with minimum GDOP. The conventional matrix inversion method for GDOP calculation demands a large amount of operation and causes high power consumption. To select the subset of the most appropriate location measurement units which give the minimum positioning error, we need to consider not only the GDOP effect but also the error statistics property. In this paper, we employ the weighted GDOP (WGDOP, instead of GDOP, to select measurement units so as to improve the accuracy of location. The handheld global positioning system (GPS devices and mobile phones with GPS chips can merely provide limited calculation ability and power capacity. Therefore, it is very imperative to obtain WGDOP accurately and efficiently. This paper proposed two formations of WGDOP with less computation when four measurements are available for location purposes. The proposed formulae can reduce the computational complexity required for computing the matrix inversion. The simpler WGDOP formulae for both the 2D and the 3D location estimation, without inverting a matrix, can be applied not only to GPS but also to wireless sensor networks (WSN and cellular communication systems. Furthermore, the proposed formulae are able to provide precise solution of WGDOP calculation without incurring any approximation error.

  3. Alpha-1-antitrypsin is an endogenous inhibitor of proinflammatory cytokine production in whole blood.

    Science.gov (United States)

    Pott, Gregory B; Chan, Edward D; Dinarello, Charles A; Shapiro, Leland

    2009-05-01

    Several observations suggest endogenous suppressors of inflammatory mediators are present in human blood. alpha-1-Antitrypsin (AAT) is the most abundant serine protease inhibitor in blood, and AAT possesses anti-inflammatory activity in vitro and in vivo. Here, we show that in vitro stimulation of whole blood from persons with a genetic AAT deficiency resulted in enhanced cytokine production compared with blood from healthy subjects. Using whole blood from healthy subjects, dilution of blood with RPMI tissue-culture medium, followed by incubation for 18 h, increased spontaneous production of IL-8, TNF-alpha, IL-1 beta, and IL-1R antagonist (IL-1Ra) significantly, compared with undiluted blood. Dilution-induced cytokine production suggested the presence of one or more circulating inhibitors of cytokine synthesis present in blood. Serially diluting blood with tissue-culture medium in the presence of cytokine stimulation with heat-killed Staphylococcus epidermidis (S. epi) resulted in 1.2- to 55-fold increases in cytokine production compared with S. epi stimulation alone. Diluting blood with autologous plasma did not increase the production of IL-8, TNF-alpha, IL-1 beta, or IL-1Ra, suggesting that the endogenous, inhibitory activity of blood resided in plasma. In whole blood, diluted and stimulated with S. epi, exogenous AAT inhibited IL-8, IL-6, TNF-alpha, and IL-1 beta significantly but did not suppress induction of the anti-inflammatory cytokines IL-1Ra and IL-10. These ex vivo and in vitro observations suggest that endogenous AAT in blood contributes to the suppression of proinflammatory cytokine synthesis.

  4. Measurement of lead isotope ratios in wine by ICP-MS and its applications to the determination of lead concentration by isotope dilution

    International Nuclear Information System (INIS)

    Augagneur, S.; Medina, B.; Grousset, F.

    1997-01-01

    Methods are described for the accurate and precise determination of lead concentrations and the isotopic composition of lead in wine samples using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). This method needs little sample preparation. A comparison with lead isotope ratios measured by Thermal Ionization Mass Spectrometry (TIMS) in three wine samples reveals a good agreement between the two techniques. The lead concentration in three certified wine samples were measured by isotope dilution (ID) and the results are compared with those obtained by external calibration ICP-MS. (orig.). With 1 fig., 4 tabs

  5. Method Development for Rapid Analysis of Natural Radioactive Nuclides Using Sector Field Inductively Coupled Plasma Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lim, J.M.; Ji, Y.Y.; Lee, H.; Park, J.H.; Jang, M.; Chung, K.H.; Kang, M.J.; Choi, G.S. [Korea Atomic Energy Research Institute (Korea, Republic of)

    2014-07-01

    As an attempt to reduce the social costs and apprehension arising from radioactivity in the environment, an accurate and rapid assessment of radioactivity is highly desirable. Naturally occurring radioactive materials (NORM) are widely spread throughout the environment. The concern with radioactivity from these materials has therefore been growing for the last decade. In particular, radiation exposure in the industry when handling raw materials (e.g., coal mining and combustion, oil and gas production, metal mining and smelting, mineral sands (REE, Ti, Zr), fertilizer (phosphate), and building materials) has been brought to the public's attention. To decide the proper handling options, a rapid and accurate analytical method that can be used to evaluate the radioactivity of radionuclides (e.g., {sup 238}U, {sup 235}U, {sup 232}Th, {sup 226}Ra, and {sup 40}K) should be developed and validated. Direct measuring methods such as alpha spectrometry, a liquid scintillation counter (LSC), and mass-spectrometry are usually used for the measurement of radioactivity in NORM samples, and they encounter the most significant difficulties during pretreatment (e.g., purification, speciation, and dilution/enrichment). Since the pretreatment process consequently plays an important role in the measurement uncertainty, method development and validation should be performed. Furthermore, a-spectrometry has a major disadvantage of a long counting time, while it has a prominent measurement capability at a very low activity level of {sup 238}U, {sup 235}U, {sup 232}Th, and {sup 226}Ra. Contrary to the α-spectrometry method, a measurement technique using ICP-MS allow radioactivity in many samples to be measured in a short time period with a high degree of accuracy and precision. In this study, a method was developed for a rapid analysis of natural radioactive nuclides using ICP-MS. A sample digestion process was established using LiBO{sub 2} fusion and Fe co-precipitation. A magnetic

  6. Alpha scintillation radon counting

    International Nuclear Information System (INIS)

    Lucas, H.F. Jr.

    1977-01-01

    Radon counting chambers which utilize the alpha-scintillation properties of silver activated zinc sulfide are simple to construct, have a high efficiency, and, with proper design, may be relatively insensitive to variations in the pressure or purity of the counter filling. Chambers which were constructed from glass, metal, or plastic in a wide variety of shapes and sizes were evaluated for the accuracy and the precision of the radon counting. The principles affecting the alpha-scintillation radon counting chamber design and an analytic system suitable for a large scale study of the 222 Rn and 226 Ra content of either air or other environmental samples are described. Particular note is taken of those factors which affect the accuracy and the precision of the method for monitoring radioactivity around uranium mines

  7. Intrinsic Ferromagnetism in the Diluted Magnetic Semiconductor Co :TiO2

    Science.gov (United States)

    Saadaoui, H.; Luo, X.; Salman, Z.; Cui, X. Y.; Bao, N. N.; Bao, P.; Zheng, R. K.; Tseng, L. T.; Du, Y. H.; Prokscha, T.; Suter, A.; Liu, T.; Wang, Y. R.; Li, S.; Ding, J.; Ringer, S. P.; Morenzoni, E.; Yi, J. B.

    2016-11-01

    Here we present a study of magnetism in Co0.05 Ti0.95 O2 -δ anatase films grown by pulsed laser deposition under a variety of oxygen partial pressures and deposition rates. Energy-dispersive spectrometry and transmission electron microscopy analyses indicate that a high deposition rate leads to a homogeneous microstructure, while a very low rate or postannealing results in cobalt clustering. Depth resolved low-energy muon spin rotation experiments show that films grown at a low oxygen partial pressure (≈10-6 torr ) with a uniform structure are fully magnetic, indicating intrinsic ferromagnetism. First principles calculations identify the beneficial role of low oxygen partial pressure in the realization of uniform carrier-mediated ferromagnetism. This work demonstrates that Co :TiO2 is an intrinsic diluted magnetic semiconductor.

  8. Intrinsic Ferromagnetism in the Diluted Magnetic Semiconductor Co:TiO_{2}.

    Science.gov (United States)

    Saadaoui, H; Luo, X; Salman, Z; Cui, X Y; Bao, N N; Bao, P; Zheng, R K; Tseng, L T; Du, Y H; Prokscha, T; Suter, A; Liu, T; Wang, Y R; Li, S; Ding, J; Ringer, S P; Morenzoni, E; Yi, J B

    2016-11-25

    Here we present a study of magnetism in Co_{0.05}Ti_{0.95}O_{2-δ} anatase films grown by pulsed laser deposition under a variety of oxygen partial pressures and deposition rates. Energy-dispersive spectrometry and transmission electron microscopy analyses indicate that a high deposition rate leads to a homogeneous microstructure, while a very low rate or postannealing results in cobalt clustering. Depth resolved low-energy muon spin rotation experiments show that films grown at a low oxygen partial pressure (≈10^{-6}  torr) with a uniform structure are fully magnetic, indicating intrinsic ferromagnetism. First principles calculations identify the beneficial role of low oxygen partial pressure in the realization of uniform carrier-mediated ferromagnetism. This work demonstrates that Co:TiO_{2} is an intrinsic diluted magnetic semiconductor.

  9. Combining Alphas via Bounded Regression

    Directory of Open Access Journals (Sweden)

    Zura Kakushadze

    2015-11-01

    Full Text Available We give an explicit algorithm and source code for combining alpha streams via bounded regression. In practical applications, typically, there is insufficient history to compute a sample covariance matrix (SCM for a large number of alphas. To compute alpha allocation weights, one then resorts to (weighted regression over SCM principal components. Regression often produces alpha weights with insufficient diversification and/or skewed distribution against, e.g., turnover. This can be rectified by imposing bounds on alpha weights within the regression procedure. Bounded regression can also be applied to stock and other asset portfolio construction. We discuss illustrative examples.

  10. Regional distribution of cytosolic and particulate 5alpha-dihydroprogesterone 3alpha-hydroxysteroid oxidoreductases in female rat brain.

    Science.gov (United States)

    Li, X; Bertics, P J; Karavolas, H J

    1997-03-01

    Numerous studies have indicated that progesterone metabolites, particularly 3alpha,5alpha-tetrahydroprogesterone, can potently influence multiple brain functions, e.g. they have the capacity to mediate gonadotropin regulation and various anticonvulsive, anesthetic and anxiolytic effects. These circulating progesterone metabolites are likely to represent only a fraction of the bioavailable pool of these steroids in that the central nervous system (CNS) also possesses enzymes that can synthesize these metabolites in situ. Therefore, because the ability of the CNS to produce these neuroactive progestins is an important consideration when assessing overall progestin function and metabolism, we measured the major progesterone metabolizing enzyme activities, namely the cytosolic NADPH and particulate NADH 5alpha-dihydroprogesterone 3alpha-hydroxysteroid oxidoreductase (3alpha-HSOR) and progesterone 5alpha-reductase activities in nine brain regions from random cycling and ovariectomized rats. These assays entailed the use of reverse isotopic dilution analysis and revealed that all three enzymic activities were present in each of the brain regions examined, but that these regions displayed differential patterns with regard to their levels of cytosolic and particulate 3alpha-HSOR activity. The cytosolic 3alpha-HSOR activity was highest in the olfactory bulb/tubercle and colliculi regions which were greater than levels in the hypothalamus/preoptic area and cerebellum which were greater than levels in the amygdala/striatum and hippocampus/dentate gyrus. Midbrain/thalamus, cerebral cortex and pons/medulla were different only from the olfactory bulb/tubercle and colliculi regions. The particulate 3alpha-HSOR activity was highest in the olfactory bulb/tubercle region followed by colliculi, hippocampus/dentate gyrus and pons/medulla which were greater than levels in the hypothalamus/preoptic area, cerebellum and amygdala/striatum. Cerebral cortex and midbrain/thalamus were

  11. Optical and Magnetic Properties of Ni Doped ZnS Diluted Magnetic Semiconductors Synthesized by Hydrothermal Method

    OpenAIRE

    Meirong Wu; Zhiqiang Wei; Wenhua Zhao; Xuan Wang; Jinlong Jiang

    2017-01-01

    Diluted magnetic semiconductors Zn1-xNixS with different consistency ratio (x = 0, 0.01, 0.03, 0.05, and 0.07) were successfully synthesized by hydrothermal method using ethylenediamine as a modifier. The influence of Ni doping concentration on the microstructure, morphology, and optical and magnetic properties of undoped and Ni doped ZnS nanocrystals was characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray energy dispersive spectrometry (X...

  12. Atomic mass spectrometry

    International Nuclear Information System (INIS)

    Sanz-Medel, A.

    1997-01-01

    The elemental inorganic analysis seems to be dominated today by techniques based on atomic spectrometry. After an evaluation of advantages and limitations of using mass analysers (ion detectors) versus conventional photomultipliers (photon detector) a brief review of the more popular techniques of the emerging Atomic Mass spectrometry is carried out. Their huge potential for inorganic trace analysis is such that in the future we could well witness how this end of the century and millennium marked the fall of the photons empire in Analytical Atomic Spectrometry. (Author)

  13. Specific heat in diluted magnetic semiconductor quantum ring

    Science.gov (United States)

    Babanlı, A. M.; Ibragimov, B. G.

    2017-11-01

    In the present paper, we have calculated the specific heat and magnetization of a quantum ring of a diluted magnetic semiconductor (DMS) material in the presence of magnetic field. We take into account the effect of Rashba spin-orbital interaction, the exchange interaction and the Zeeman term on the specific heat. We have calculated the energy spectrum of the electrons in diluted magnetic semiconductor quantum ring. Moreover we have calculated the specific heat dependency on the magnetic field and Mn concentration at finite temperature of a diluted magnetic semiconductor quantum ring.

  14. Alpha-bungarotoxin binding to target cell in a developing visual system by carboxylated nanodiamond

    Energy Technology Data Exchange (ETDEWEB)

    Liu, K-K; Chen, P-Y; Lee, Tony J F; Chao, J-I [Institute of Pharmacology and Toxicology, Tzu Chi University, Hualien 970, Taiwan (China); Chen, M-F [Neuro-Medical Scientific Center, Tzu Chi General Hospital, Hualien 970, Taiwan (China); Cheng, C-L [Department of Physics, National Dong Hwa University, Hualien 974, Taiwan (China); Chang, C-C [Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu 300, Taiwan (China); Ho, Y-P [Department of Chemistry, National Dong Hwa University, Hualien 974, Taiwan (China)], E-mail: chaoji@mail.tcu.edu.tw

    2008-05-21

    Biological molecules conjugating with nanoparticles are valuable for applications including bio-imaging, bio-detection, and bio-sensing. Nanometer-sized diamond particles have excellent electronic and chemical properties for bio-conjugation. In this study, we manipulated the carboxyl group produced on the surface of nanodiamond (carboxylated nanodiamond, cND) for conjugating with alpha-bungarotoxin ({alpha}-BTX), a neurotoxin derived from Bungarus multicinctus with specific blockade of alpha7-nicotinic acetylcholine receptor ({alpha}7-nAChR). The electrostatic binding of cND-{alpha}-BTX was mediated by the negative charge of the cND and the positive charge of the {alpha}-BTX in physiological pH conditions. Sodium dodecyl sulfate-polyacrylamide gel analysis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI/TOF-MS) spectra displayed that {alpha}-BTX proteins were conjugated with cND particles via non-covalent bindings. The green fluorescence of the cND particles combining with the red fluorescence of tetramethylrhodamine-labeled {alpha}-BTX presented a yellow color at the same location, which indicated that {alpha}-BTX proteins were conjugated with cND particles. Xenopus laevis's oocytes expressed the human {alpha}7-nAChR proteins by microinjection with {alpha}7-nAChR mRNA. The cND-{alpha}-BTX complexes were bound to {alpha}7-nAChR locating on the cell membrane of oocytes and human lung A549 cancer cells analyzed by laser scanning confocal microscopy. The choline-evoked {alpha}7-nAChR-mediated inward currents of the oocytes were blocked by cND-{alpha}-BTX complexes in a concentration-dependent manner using two-electrode voltage-clamp recording. Furthermore, the fluorescence intensity of cND-{alpha}-BTX binding on A549 cells could be quantified by flow cytometry. These results indicate that cND-conjugated {alpha}-BTX still preserves its biological activity in blocking the function of {alpha}7-nAChR, and provide a visual

  15. Evaluation of method for phthalate extraction from milk related to milk dilution ratio

    Directory of Open Access Journals (Sweden)

    Milojković Danica S.

    2015-01-01

    Full Text Available Liquid-liquid extraction techniques were compared coupled with gas chromatography-mass spectrometry (GC-MS, for the extraction and the determination of four phthalates: dimethyl phthalate (DMP, di-n-butyl phthalate (DBP, benzyl butyl phthalate (BBP and di-(2-ethylhexyl phthalate (DEHP in six different kinds of milk-based samples. Extraction factors: sample preparation, organic solvent type and volume, salt effect, agitation and the extraction time were optimized. The ion of base peaks (m/z 149 for DBP, BBP and DEHP and m/z 163 for DMP for investigated phthalates were selected for the screening studies. The acquisition was performed at the selected ion monitoring mode. The MSD response for GC-MS phthalate calibration standards was linear between 0.25 and 2.50 μg mL-1 with calculated LODs between 0.01 μg mL-1 to 0.04 μg mL-1 and LOQs of 0.05 μg mL-1 to 0.12 μg mL-1, while repeatability was between 1.7 % to 4.9 % RSD. The study demonstrated an increase of the recovery of less polar phthalates in matrix milk standards by matrix dilution. Recovery for hydrophilic phthalates, like DMP, was not changed by matrix dilution and it was continuously low for the investigated method. Two spiking levels were tested for influence of matrix dilution on phthalate recovery, showed the same trend. [Projekat Ministarstva nauke Republike Srbije, br. 31060

  16. Isotope Dilution - Thermal Ionisation Mass Spectrometric Analysis for Tin in a Fly Ash Material

    International Nuclear Information System (INIS)

    Hernandez, C.; Fernandez, M.; Quejido, A. L.

    2006-01-01

    Isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) analysis has been applied to the determination of tin in a fly ash sample supplied by the EC Joint Research Centre (Ispra, Italy). The proposed procedure includes the silica gel/phosphoric acid technique for tin thermal ionisation activation and a strict heating protocol for isotope ratio measurements. Instrumental mass discrimination factor has been previously determined measuring a natural tin standard solution. Spike solutions has been prepared from 112Sn-enriched metal and quantified by reverse isotope dilution analysis. Two sample aliquots were spiked and tin was extracted with 4,5 M HCI during 25 min ultrasound esposure time. Due to the complex matrix of this fly ash material, a two-steps purification stage using ion-exchange chromatography was required prior TIMS analysis. Obtained results for the two sample-spike blends (10,10 + - 0,55 y 10,50 + - 0,64 imolg-1) are comprarable, both value and uncertainty. Also a good reproducibility is observed between measurements. The proposed ID-TIMS procedure, as a primary method and due to the lack of fly ash reference material certified for tin content, can be used to validate more routine methodologies applied to tin determination in this kind of materials. (Author) 75 refs

  17. Isotope dilution-thermal ionisation mass spectrometric analysis for tin in a fly ash material

    International Nuclear Information System (INIS)

    Hernandez, Carolina; Fernandez, Marta; Quejido, Alberto J.; Sanchez, Dolores M.; Morante, Ramon; Martin, Raul

    2006-01-01

    Isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) analysis has been applied to the determination of tin in a fly ash sample supplied by the EC Joint Research Centre (Ispra, Italy). The proposed procedure includes the silica gel/phosphoric acid technique for tin thermal ionisation activation and a strict heating protocol for isotope ratio measurements. Instrumental mass discrimination factor has been previously determined measuring a natural tin standard solution. Spike solution has been prepared from 112 Sn-enriched metal and quantified by reverse isotope dilution analysis. Two sample aliquots were spiked and tin was extracted with 4.5 M HCl during 25 min ultrasound exposure time. Due to the complex matrix of this fly ash material, a two-step purification stage using ion-exchange chromatography was required prior TIMS analysis. Obtained results for the two sample-spike blends (10.11 ± 0.55 and 10.50 ± 0.64 μmol g -1 ) are comparable, both value and uncertainty. Also a good reproducibility is observed between measurements. The proposed ID-TIMS procedure, as a primary method and due to the lack of fly ash reference materials certified for tin content, can be used to validate more routine methodologies applied to tin determination in this kind of samples

  18. Pulsed Dilution Method for the Recovery of Aggregated Mouse TNF-α

    Directory of Open Access Journals (Sweden)

    Merat Mahmoodi

    2017-05-01

    Full Text Available Background: The expression of mouse tumor necrosis factor alpha (TNF-α in Escherichia coli is a favorable way to get high yield of protein; however, the formation of cytoplasmic inclusion bodies, which is the consequence of insoluble accumulated proteins, is a major obstacle in this system. To overcome this obstacle, we used a pulsed dilution method to convert the product to its native conformation. Methods: Reducing agent and guanidine hydrochloride were used to solubilize inclusion bodies formed after TNF-(α expression. Then, the refolding procedure was performed by pulsed dilution of the denatured protein into a refolding buffer. The properly-folded protein was purified by metal affinity chromatography. Results: SDS-PAGE showed a 19.9 kDa band related to the mature TNF-(α protein. The protein was recognized by anti-mouse TNF-(α on western blots. The final concentration of the purified recombinant TNF-(α was 62.5 μg/mL. Conclusions: Our study demonstrates the efficiency of this method to produce a high yield of folded mature TNF- (α.

  19. Role of {sup 8}Be heavy stripping mechanism in the {alpha} + {sup 12}C inelastic scattering to the near-3{alpha}-threshold states in {sup 12}C

    Energy Technology Data Exchange (ETDEWEB)

    Belyaeva, T. L. [Universidad Autonoma del Estado de Mexico (Mexico); Danilov, A. N.; Demyanova, A. S. [NRC Kurchatov Institute (Russian Federation); Goncharov, S. A., E-mail: gsa@srd.sinp.msu.ru [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation); Ogloblin, A. A. [NRC Kurchatov Institute (Russian Federation); Perez-Torres, R. [Estado de Mexico, Instituto Tecnologico del Valle de Toluca (Mexico)

    2011-11-15

    The angular distributions of {alpha} + {sup 12}C elastic and inelastic (to the 4.44 MeV, 2{sup +}; 7.65MeV, 0{sup +}; and 9.64MeV, 3{sup -} states) scattering at 110 MeV are characterized by pronounced enhancement and strong oscillations at large angles. We performed calculations of the differential cross sections of these reactions assuming a potential scattering in the forward hemisphere and the direct transfer of {sup 8}Be cluster {theta}{sub c.m.} > 90 Degree-Sign . We showed that the {alpha} + {sup 8}Be cluster configuration with relative angular momentum L = 0 dominates in the Hoyle state being 4.4 times larger than that in the ground state. This result also contributes to the verification of {alpha}BEC hypothesis and is consistent with the conjecture of a dilute 3{alpha} structure of the Hoyle state. In the 9.64 MeV, 3{sup -} state, a positive interference of all allowed {alpha} + {sup 8}Be configurations with a dominance of the p-orbital (49%) {alpha}-{sup 8}Be relative motion is found. This finding manifests the exotic 3{alpha}, but hardly condensed structure of the 9.64-MeV 3{sup -} state in {sup 12}C.

  20. Molecular Imaging Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Kovac, S.

    2009-05-01

    Full Text Available Molecular imaging mass spectrometry (IMS is a recently developed method for direct determination of spatial distribution of biopolymers, preferably proteins on cell surface and tissues. Imaging mass spectrometry data are mainly based on Matrix-Assisted Laser Desorption/Ionization- Time of Flight (MALDI TOF. The MALDI TOF based imaging mass spectrometry was applied for determination of changes in kidney tissue of sensitive mice after poisoning with aristolochic acid I. The second application presented here were changes in the gastric tissue in mice after infection with Helicobacter pylori, as a model of gastric cancer in humans caused by this pathogen microorganism. Molecular imaging mass spectrometry can be applied in medicine, mostly for identification of candidate biomarkers for malignant and non-malignant diseases. Furthermore, imaging MS has almost unlimited capacity in agriculture, food technology and biotechnology, e. g. for monitoring, process development and quality control of manufactured tissue of animal, plant and microbial origin.

  1. Software for nuclear spectrometry

    International Nuclear Information System (INIS)

    1998-10-01

    The Advisory Group Meeting (AGM) on Software for Nuclear Spectrometry was dedicated to review the present status of software for nuclear spectrometry and to advise on future activities in this field. Because similar AGM and consultant's meetings had been held in the past; together with an attempt to get more streamlined, this AGM was devoted to the specific field of software for gamma ray spectrometry. Nevertheless, many of the issues discussed and the recommendations made are of general concern for any software on nuclear spectrometry. The report is organized by sections. The 'Summary' gives conclusions and recommendations adopted at the AGM. These conclusions and recommendations resulted from the discussions held during and after presentations of the scientific and technical papers. These papers are reported here in their integral form in the following Sections

  2. Ion mobility spectrometry

    CERN Document Server

    Eiceman, GA

    2005-01-01

    Key Developments for Faster, More Precise Detection Capabilities Driven by the demand for the rapid and advanced detection of explosives, chemical and biological warfare agents, and narcotics, ion mobility spectrometry (IMS) undergone significant refinements in technology, computational capabilities, and understanding of the principles of gas phase ion chemistry and mobility. Beginning with a thorough discussion of the fundamental theories and physics of ion mobility, Ion Mobility Spectrometry, Second Edition describes the recent advances in instrumentation and newly

  3. Identification of a novel bean alpha-amylase inhibitor with chitinolytic activity.

    Science.gov (United States)

    Dayler, Charles S A; Mendes, Paulo A M; Prates, Maura V; Bloch, Carlos; Franco, Octavio L; Grossi-de-Sá, Maria F

    2005-10-24

    Zabrotes subfasciatus is a devastating starch-dependent storage bean pest. In this study, we attempted to identify novel alpha-amylase inhibitors from wild bean seeds, with efficiency toward pest alpha-amylases. An inhibitor named Phaseolus vulgaris chitinolytic alpha-amylase inhibitor (PvCAI) was purified and mass spectrometry analyses showed a protein with 33330 Da with the ability to form dimers. Purified PvCAI showed significant inhibitory activity against larval Z. subfasciatus alpha-amylases with no activity against mammalian enzymes. N-terminal sequence analyses showed an unexpected high identity to plant chitinases from the glycoside hydrolase family 18. Furthermore, their chitinolytic activity was also detected. Our data provides compelling evidence that PvCAI also possessed chitinolytic activity, indicating the emergence of a novel alpha-amylase inhibitor class.

  4. A Cold Cycle Dilution Refrigerator for Space Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The cold cycle dilution refrigerator is a continuous refrigerator capable of cooling to temperatures below 100 mK that makes use of a novel thermal magnetic pump....

  5. Sorption-cooled continuous miniature dilution refrigeration for astrophysical applications

    Science.gov (United States)

    May, Andrew J.; Calisse, Paolo G.; Coppi, Gabriele; Haynes, Vic; Martinis, Lorenzo; McCulloch, Mark A.; Melhuish, Simon J.; Piccirillo, Lucio

    2016-07-01

    A progress report is provided on the development of a tiltable continuous miniature dilution refrigerator and associated 3He/4He sorption coolers. These systems are currently being developed to provide sub-Kelvin cooling of the bolometer arrays for several ground- and balloon-based experiments which aim to measure the polarization of the Cosmic Microwave Background (QUBIC, LSPE and POLARBEAR-2). The novel tiltable miniaturised system benefits from a lack of external circulation pumps and a mechanically simple design. The condenser of the twin-pumped recirculating diluter is cooled continuously by two 3He/4He sorption coolers. The sorption pumps are operated by convective heat switches. The dilution unit features a thermally separated mixing chamber, still and step heat exchangers. The designs and analyses of both the sorption coolers and the diluter are reported; both systems have been manufactured and are presently under test.

  6. Treatment of alpha bearing wastes

    International Nuclear Information System (INIS)

    1988-01-01

    This report deals with the current state of the art of alpha waste treatment, which is an integral part of the overall nuclear waste management system. The International Atomic Energy Agency (IAEA) defines alpha bearing waste as 'waste containing one or more alpha emitting radionuclides, usually actinides, in quantities above acceptable limits'. The limits are established by national regulatory bodies. The limits above which wastes are considered as alpha contaminated refer to the concentrations of alpha emitters that need special consideration for occupational exposures and/or potential safety, health, or environmental impact during one or more steps from generation through disposal. Owing to the widespread use of waste segregation by source - that is, based upon the 'suspect origin' of the material - significant volumes of waste are being handled as alpha contaminated which, in fact, do not require such consideration by reason of risk or environmental concern. The quantification of de minimis concepts by national regulatory bodies could largely contribute to the safe reduction of waste volumes and associated costs. Other factors which could significantly contribute to the reduction of alpha waste arisings are an increased application of assaying and sorting, instrumentation and the use of feedback mechanisms to control or modify the processes which generate these wastes. Alpha bearing wastes are generated during fabrication and reprocessing of nuclear fuels, decommissioning of alpha contaminated facilities, and other activities. Most alpha wastes are contact handled, but a small portion may require shielding or remote handling because of high levels of neutron (n), beta (β), or gamma (γ) emissions associated with the waste material. This report describes the sources and characteristics of alpha wastes and strategies for alpha waste management. General descriptions of treatment processes for solid and liquid alpha wastes are included. 71 refs, 14 figs, 9 tabs

  7. The alpha effect

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    Much of the recent interest in RAM system reliability stems from concern over alpha particle soft error rates reported for the initial 64 k RAMs. With increasing memory density likely in the next few years the problem of soft errors is rearing its head again. A few years ago ITT carried out experiments on 16k RAMs and found no significant problems. However, recent tests have shown a raise in the number of soft errors with 64k RAMs, and the launch of 256k and 512k memories is likely to make the problem acute

  8. Alpha-mannosidosis

    Directory of Open Access Journals (Sweden)

    Nilssen Øivind

    2008-07-01

    Full Text Available Abstract Alpha-mannosidosis is an inherited lysosomal storage disorder characterized by immune deficiency, facial and skeletal abnormalities, hearing impairment, and intellectual disability. It occurs in approximately 1 of 500,000 live births. The children are often born apparently normal, and their condition worsens progressively. Some children are born with ankle equinus or develop hydrocephalus in the first year of life. Main features are immune deficiency (manifested by recurrent infections, especially in the first decade of life, skeletal abnormalities (mild-to-moderate dysostosis multiplex, scoliosis and deformation of the sternum, hearing impairment (moderate-to-severe sensorineural hearing loss, gradual impairment of mental functions and speech, and often, periods of psychosis. Associated motor function disturbances include muscular weakness, joint abnormalities and ataxia. The facial trait include large head with prominent forehead, rounded eyebrows, flattened nasal bridge, macroglossia, widely spaced teeth, and prognathism. Slight strabismus is common. The clinical variability is significant, representing a continuum in severity. The disorder is caused by lysosomal alpha-mannosidase deficiency. Alpha-mannosidosis is inherited in an autosomal recessive fashion and is caused by mutations in the MAN2B1 gene located on chromosome 19 (19 p13.2-q12. Diagnosis is made by measuring acid alpha-mannosidase activity in leukocytes or other nucleated cells and can be confirmed by genetic testing. Elevated urinary secretion of mannose-rich oligosaccharides is suggestive, but not diagnostic. Differential diagnoses are mainly the other lysosomal storage diseases like the mucopolysaccharidoses. Genetic counseling should be given to explain the nature of the disease and to detect carriers. Antenatal diagnosis is possible, based on both biochemical and genetic methods. The management should be pro-active, preventing complications and treating

  9. Assessment of measurement result uncertainty in determination of 210Pb with the focus on matrix composition effect in gamma-ray spectrometry

    International Nuclear Information System (INIS)

    Iurian, A.R.; Pitois, A.; Kis-Benedek, G.; Migliori, A.; Padilla-Alvarez, R.; Ceccatelli, A.

    2016-01-01

    Reference materials were used to assess measurement result uncertainty in determination of 210 Pb by gamma-ray spectrometry, liquid scintillation counting, or indirectly by alpha-particle spectrometry, using its daughter 210 Po in radioactive equilibrium. Combined standard uncertainties of 210 Pb massic activities obtained by liquid scintillation counting are in the range 2–12%, depending on matrices and massic activity values. They are in the range 1–3% for the measurement of its daughter 210 Po using alpha-particle spectrometry. Three approaches (direct computation of counting efficiency and efficiency transfer approaches based on the computation and, respectively, experimental determination of the efficiency transfer factors) were applied for the evaluation of 210 Pb using gamma-ray spectrometry. Combined standard uncertainties of gamma-ray spectrometry results were found in the range 2–17%. The effect of matrix composition on self-attenuation was investigated and a detailed assessment of uncertainty components was performed. - Highlights: • Confirmed 210 Pb certified values by LSC and alpha-particle spectrometry ( 210 Po). • Assessed 210 Po measurement result uncertainty by alpha-particle spectrometry. • Matrix composition effect on gamma-ray spectrometry measurement result uncertainty. • Assessment of 210 Pb measurement result uncertainty by gamma-ray spectrometry. • Comparison of techniques and approaches: ‘fit-for-purpose’ considerations.

  10. Dilution Refrigeration of Multi-Ton Cold Masses

    CERN Document Server

    Wikus, P; CERN. Geneva

    2007-01-01

    Dilution refrigeration is the only means to provide continuous cooling at temperatures below 250 mK. Future experiments featuring multi-ton cold masses require a new generation of dilution refrigeration systems, capable of providing a heat sink below 10 mK at cooling powers which exceed the performance of present systems considerably. This thesis presents some advances towards dilution refrigeration of multi-ton masses in this temperature range. A new method using numerical simulation to predict the cooling power of a dilution refrigerator of a given design has been developed in the framework of this thesis project. This method does not only allow to take into account the differences between an actual and an ideal continuous heat exchanger, but also to quantify the impact of an additional heat load on an intermediate section of the dilute stream. In addition, transient behavior can be simulated. The numerical model has been experimentally verified with a dilution refrigeration system which has been designed, ...

  11. Effects of dissolved species on radiolysis of diluted seawater

    International Nuclear Information System (INIS)

    Hata, Kuniki; Hanawa, Satoshi; Kasahara, Shigeki; Motooka, Takafumi; Tsukada, Takashi; Muroya, Yusa; Yamashita, Shinichi; Katsumura, Yosuke

    2014-01-01

    Fukushima Daiichi Nuclear Power Plants (NPPs) experienced seawater injection into the cores and fuel pools as an emergent measure after the accident. After the accident, retained water has been continuously desalinized, and subsequently the concentration of chloride ion (Cl - ) has been kept at a lower level these days. These ions in seawater are known to affect water radiolysis, which causes the production of radiolytic products, such as hydrogen peroxide (H 2 O 2 ), molecular hydrogen (H 2 ) and molecular oxygen (O 2 ). However, the effects of dissolved ions relating seawater on the production of the stable radiolytic products are not well understood in the diluted seawater. To understand of the production behavior in diluted seawater under radiation, radiolysis calculations were carried out. Production of H 2 is effectively suppressed by diluting by up to vol10%. The concentrations of oxidants (H 2 O 2 and O 2 ) are also suppressed by dilution of dissolved species. The effect of oxidants on corrosion of materials is thought to be low when the seawater was diluted by less than 1 vol% by water. It is also shown that deaeration is one of the effective measure to suppress the concentrations of oxidants at a lower level for any dilution conditions. (author)

  12. alpha-particle radioactivity from LR 115 by two methods of analysis

    CERN Document Server

    Azkour, K; Adloff, J C; Pape, A

    1999-01-01

    LR115 track detectors were exposed to samples of Moroccan phosphate and phosphogypsum to measure their alpha-particle radioactivity. Then two formalisms were used for the dosimetry: simulation by a Monte Carlo method and determination of concentrations from a numerically integrated track registration equation. The results were compared with those deduced gamma-ray spectrometry.

  13. The role of sulfur and sulfur isotope dilution analysis in quantitative protein analysis.

    Science.gov (United States)

    Rappel, Christina; Schaumlöffel, Dirk

    2008-01-01

    The element sulfur is almost omnipresent in all natural proteomes and plays a key role in protein quantification. Incorporated in the amino acids cysteine and methionine, it has been served as target for many protein-labeling reactions in classic quantitative proteomic approaches based on electrospray or MALDI mass spectrometry. This critical review discusses the potential and limitations of sulfur isotope dilution analysis (IDA) by inductively coupled plasma-mass spectrometry (ICP-MS) for absolute protein quantification. The development of this approach was made possible due to the improved sensitivity and accuracy of sulfur isotope ratio measurement by ICP-MS in recent years. The unique feature of ICP-MS, compound-independent ionization, enables compound (species)-unspecific sulfur IDA. This has the main advantage that only one generic sulfur standard (i.e., one isotopically labeled sulfur spike) is required to quantify each peptide or protein in a sample provided that they are completely separated in chromatography or electrophoresis and that their identities are known. The principles of this approach are illustrated with selected examples from the literature. The discussion includes also related fields of P/S and metal/S ratio measurements for the determination of phosphorylation degrees of proteins and stoichiometries in metalloproteins, respectively. Emerging new areas and future trends such as protein derivatization with metal tags for improved sensitivity of protein detection in ICP-MS are discussed.

  14. Alpha activity measurement with lsc

    International Nuclear Information System (INIS)

    Dobrin, R. I.; Dulama, C. N.; Ciocirlan, C. N.; Toma, A.; Stoica, S. M.; Valeca, M.

    2013-01-01

    Recently, we showed that the alpha activity in liquid samples can be measured using a liquid scintillation analyzer without alpha/beta discrimination capability. The purpose of this work was to evaluate the performances of the method and to optimize the procedure of the sample preparation. A series of tests was performed to validate the procedure of alpha emitting radionuclides extraction in aqueous samples with Actinide Resin, especially regarding to the contact time required to extract all alpha nuclides. The main conclusions were that a minimum 18 hours stirring time is needed to achieve a percent recovery of the alpha nuclides grater than 90% and that the counting efficiency of alphas measurements with LSC is nearly 100%. (authors)

  15. SELECTIVE INHIBITION OF HEPATITIS C VIRUS REPLICATION BY ALPHA-ZAM, A NIGELLA SATIVA SEED FORMULATION.

    Science.gov (United States)

    Oyero, Olufunmilayo G; Toyama, Masaaki; Mitsuhiro, Naoki; Onifade, Abdulfatah A; Hidaka, Akemi; Okamoto, Mika; Baba, Masanori

    2016-01-01

    Hepatitis C virus (HCV) infection became curable because of the development of direct acting antivirals (DAAs). However, the high cost of DAAs has greatly impeded their potential impact on the treatment of HCV infection. As a result, hepatitis C will continue to cause substantial morbidity, and mortality among chronically infected individuals in low and middle income countries. Thus, urgent need exists for developing cheaper drugs available to hepatitis C patients in these countries. Alpha-zam, an indigenous herbal formulation from Nigella sativa seed, was examined for its anti-HCV activity and cytotoxicity in genotype 1b HCV replicon cells. The antiviral activity was determined by luciferase expression and viral RNA synthesis, while the cytotoxicity was assessed by viable cell number and glyceraldehyde-3-phosphate dehydrogenase RNA synthesis in the replicon cells. Alpha-zam was found to be a selective inhibitor of HCV replication. The 50% effective dilution and 50% cytotoxic dilution of Alpha-zam were 761- and < 100-fold, respectively, in the subgenomic replicon cells LucNeo#2. Its selective inhibition of HCV was also confirmed by HCV RNA levels in LucNeo#2 and in the full-genome HCV replicon cells NNC#2 using real-time reverse transcriptase polymerase chain reaction. Furthermore, the anti-HCV activity of Alpha-zam was not due to the induction of interferon. Alpha-zam selectively inhibits HCV replication and therefore has potential for a novel antiviral agent against HCV infection.

  16. Formulation and Validation of a Computational Model for a Dilute Biomass Slurry Undergoing Rotational Mixing

    Energy Technology Data Exchange (ETDEWEB)

    Sprague, Michael A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stickel, Jonathan J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sitaraman, Hariswaran [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Crawford, Nathan [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-02-17

    In this paper we develop a computational model for the mixing and transport of a dilute biomass slurry. The objective was to create a sufficiently simple and efficient model for biomass transport that can be coupled with reaction models for the study of conversion of cellulosic biomass into fermentable sugars. Our target system is 5%-by-mass ..alpha..-cellulose, which is our proxy for more complex lignocellulosic biomass. In the authors' previous work, an experimental investigation with ..alpha..-cellulose under two vane-mixer configurations showed a bifurcation between a settling regime, for which settling effects dominate, and a suspended regime, for which solids are mostly suspended. Here, a mixed-fluid model was chosen, for which the model for the mixture-velocity field is the incompressible Navier-Stokes equations under the Boussinesq approximation for buoyancy. Solids transport includes solids motion due to diffusion, settling, advection, and shear. Comparison of simulated and experimental results show good agreement in the suspended regime, and in capturing the bifurcation rate. While the model captured well the distribution of solids in the settling regime, the model was incapable of capturing the high torque values seen in experiments with vanishing mixer rotation rate.

  17. Prostaglandin E1 and prostaglandin F2 alpha in exudate in nickel allergy

    DEFF Research Database (Denmark)

    Lerche, A; Bisgaard, H; Kassis, V

    1989-01-01

    Ten nickel-allergic patients and 5 healthy control subjects participated in a study of the kinetics of the flux and concentration of migrated leukocytes and extracellular PGE1 and PGF2 alpha during a 48 h period, using a skin chamber technique. The patients were provided with two skin chambers, one...... with and one without nickel challenge. A higher flux of leukocytes, PGE1 and PGF2 alpha was observed during the second day of allergen exposure, while the concentrations probably due to dilution were unchanged or diminished, indicating an unspecific role of the prostaglandins during the contact allergic...

  18. Highly sensitive quantification of 7alpha-hydroxy-4-cholesten-3-one in human serum by LC-ESI-MS/MS.

    Science.gov (United States)

    Honda, Akira; Yamashita, Kouwa; Numazawa, Mitsuteru; Ikegami, Tadashi; Doy, Mikio; Matsuzaki, Yasushi; Miyazaki, Hiroshi

    2007-02-01

    We describe a highly sensitive and specific method for the quantification of serum 7alpha-hydroxy-4-cholesten-3-one (C4), which has been used as a biomarker for bile acid biosynthesis. This method is based upon a stable isotope dilution technique by liquid chromatography-tandem mass spectrometry (LC-MS/MS). C4 was extracted from human serum (2-50 mul) by a salting-out procedure, derivatized into the picolinoyl ester (C4-7alpha-picolinate), and then purified using a disposable C(18) cartridge. The resulting picolinoyl ester derivative of C4 was quantified by LC-MS/MS using the electrospray ionization mode. The detection limit of the C4 picolinoyl ester was found to be 100 fg (signal-to-noise ratio = 10), which was approximately 1,000 times more sensitive than the detection limit of C4 with a conventional HPLC-ultraviolet method. The relative standard deviations between sample preparations and between measurements by our method were calculated to be 5.7% and 3.9%, respectively, by one-way layout analysis. The recovery experiments were performed using serum spiked with 20.0-60.0 ng/ml C4 and were validated by a polynomial equation. The results showed that the estimated concentration with 95% confidence limit was 23.1 +/- 2.8 ng/ml, which coincided completely with the observed X(0) +/- SD = 23.3 +/- 1.0 ng/ml with a mean recovery of 93.4%. This method provides highly reliable and reproducible results for the quantification of C4, especially in small volumes of blood samples.

  19. Molecular characterization of alpha 1- and alpha 2-adrenoceptors.

    Science.gov (United States)

    Harrison, J K; Pearson, W R; Lynch, K R

    1991-02-01

    Three 'alpha 1-adrenoceptors' and three 'alpha 2-adrenoceptors' have now been cloned. How closely do these receptors match the native receptors that have been identified pharmacologically? What are the properties of these receptors, and how do they relate to other members of the cationic amine receptor family? Kevin Lynch and his colleagues discuss these questions in this review.

  20. Modeling syngas-fired gas turbine engines with two dilutants

    Science.gov (United States)

    Hawk, Mitchell E.

    2011-12-01

    Prior gas turbine engine modeling work at the University of Wyoming studied cycle performance and turbine design with air and CO2-diluted GTE cycles fired with methane and syngas fuels. Two of the cycles examined were unconventional and innovative. The work presented herein reexamines prior results and expands the modeling by including the impacts of turbine cooling and CO2 sequestration on GTE cycle performance. The simple, conventional regeneration and two alternative regeneration cycle configurations were examined. In contrast to air dilution, CO2 -diluted cycle efficiencies increased by approximately 1.0 percentage point for the three regeneration configurations examined, while the efficiency of the CO2-diluted simple cycle decreased by approximately 5.0 percentage points. For CO2-diluted cycles with a closed-exhaust recycling path, an optimum CO2-recycle pressure was determined for each configuration that was significantly lower than atmospheric pressure. Un-cooled alternative regeneration configurations with CO2 recycling achieved efficiencies near 50%, which was approximately 3.0 percentage points higher than the conventional regeneration cycle and simple cycle configurations that utilized CO2 recycling. Accounting for cooling of the first two turbine stages resulted in a 2--3 percentage point reduction in un-cooled efficiency, with air dilution corresponding to the upper extreme. Additionally, when the work required to sequester CO2 was accounted for, cooled cycle efficiency decreased by 4--6 percentage points, and was more negatively impacted when syngas fuels were used. Finally, turbine design models showed that turbine blades are shorter with CO2 dilution, resulting in fewer design restrictions.

  1. Comparison of Dilution, Filtration, and Microwave Digestion Sample Pretreatments in Elemental Profiling of Wine by ICP-MS

    Directory of Open Access Journals (Sweden)

    Joshua Godshaw

    2017-09-01

    Full Text Available Wine elemental composition varies by cultivar, geographic origin, viticultural and enological practices, and is often used for authenticity validation. Elemental analysis of wine by Inductively Coupled Plasma Mass Spectrometry (ICP-MS is challenging due to the potential for non-spectral interferences and plasma instability arising from organic matrix components. Sample preparation mitigates these interferences, however, conflicting recommendations of best practices in ICP-MS analysis of wine have been reported. This study compared direct dilution, microwave-assisted acid digestion, and two filtration sample pretreatments, acidification prior to filtration and filtration followed by acidification, in elemental profiling of one white and three red table wines by ICP-MS. Of 43 monitored isotopes, 37 varied by sample preparation method, with significantly higher results of 17 isotopes in the microwave-digested samples. Both filtration treatments resulted in lower results for 11 isotopes compared to the other methods. Finally, isotope dilution determination of copper based on natural abundances and the 63Cu:65Cu instrument response ratio agreed with external calibration and confirmed a significant sample preparation effect. Overall, microwave digestion did not compare favorably, and direct dilution was found to provide the best compromise between ease of use and result accuracy and precision, although all preparation strategies were able to differentiate the wines.

  2. Comparison of Dilution, Filtration, and Microwave Digestion Sample Pretreatments in Elemental Profiling of Wine by ICP-MS.

    Science.gov (United States)

    Godshaw, Joshua; Hopfer, Helene; Nelson, Jenny; Ebeler, Susan E

    2017-09-25

    Wine elemental composition varies by cultivar, geographic origin, viticultural and enological practices, and is often used for authenticity validation. Elemental analysis of wine by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is challenging due to the potential for non-spectral interferences and plasma instability arising from organic matrix components. Sample preparation mitigates these interferences, however, conflicting recommendations of best practices in ICP-MS analysis of wine have been reported. This study compared direct dilution, microwave-assisted acid digestion, and two filtration sample pretreatments, acidification prior to filtration and filtration followed by acidification, in elemental profiling of one white and three red table wines by ICP-MS. Of 43 monitored isotopes, 37 varied by sample preparation method, with significantly higher results of 17 isotopes in the microwave-digested samples. Both filtration treatments resulted in lower results for 11 isotopes compared to the other methods. Finally, isotope dilution determination of copper based on natural abundances and the 63 Cu: 65 Cu instrument response ratio agreed with external calibration and confirmed a significant sample preparation effect. Overall, microwave digestion did not compare favorably, and direct dilution was found to provide the best compromise between ease of use and result accuracy and precision, although all preparation strategies were able to differentiate the wines.

  3. Quantification of urinary 0,0'-dityrosine, a biomarker for oxidative damage to proteins, by high performance liquid chromatography with triple quadrupole tandem mas spectrometry. A comparison with ion-trap tandem mass spectrometry.

    NARCIS (Netherlands)

    Orhan, H.; Coolen, S.; Meerman, J.H.N.

    2005-01-01

    We recently described an isotope dilution reversed-phase liquid chromatography-atmospheric pressure chemical ionization-ion-trap-tandem mass spectrometry (HPLC-APCI-MS/MS) method for the quantitative determination of oxidized amino acids in human urine, including o,o′-dityrosine, a specific marker

  4. Alpha wastes treatment

    International Nuclear Information System (INIS)

    Thouvenot, P.

    2000-01-01

    Alter 2004, the alpha wastes issued from the Commissariat a l'Energie Atomique installations will be sent to the CEDRA plant. The aims of this installation are decontamination and wastes storage. Because of recent environmental regulations concerning ozone layer depletion, the use of CFC 113 in the decontamination unit, as previously planned, is impossible. Two alternatives processes are studied: the AVD process and an aqueous process including surfactants. Best formulations for both processes are defined issuing degreasing kinetics. It is observed that a good degreasing efficiency is linked to a good decontamination efficiency. Best results are obtained with the aqueous process. Furthermore, from the point of view of an existing waste treatment unit, the aqueous process turns out to be more suitable than the AVD process. (author)

  5. Determination of cadmium in aluminium by atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Batistoni, D.A.; Erlijman, L.H.

    1978-12-01

    A direct method for the determination of cadmium in elemental aluminium is described. Metal samples are dissolved in diluted hydrochloric acid and cadmium is determined by atomic absorption spectrometry in an air-acetylene flame. Interference by non-specific absorption observed at the analytical wavelength incorrected for by means of a non-absorbing line emitted by the hollow-cathode lamp. Relatively large amounts of arsenic do not interfere. The minimun determinable concentration of cadmium for this procedure is 2-3 ppm, expressed on aluminium basis. (author) [es

  6. Ion Mobility Spectrometry (IMS) and Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Shvartsburg, Alexandre A.

    2010-04-20

    In a media of finite viscosity, the Coulomb force of external electric field moves ions with some terminal speed. This dynamics is controlled by “mobility” - a property of the interaction potential between ions and media molecules. This fact has been used to separate and characterize gas-phase ions in various modes of ion mobility spectrometry (IMS) developed since 1970. Commercial IMS devices were introduced in 1980-s for field detection of volatile traces such as explosives and chemical warfare agents. Coupling to soft-ionization sources, mass spectrometry (MS), and chromatographic methods in 1990-s had allowed IMS to handle complex samples, enabling new applications in biological and environmental analyses, nanoscience, and other areas. Since 2003, the introduction of commercial systems by major instrument vendors started bringing the IMS/MS capability to broad user community. The other major development of last decade has been the differential IMS or “field asymmetric waveform IMS” (FAIMS) that employs asymmetric time-dependent electric field to sort ions not by mobility itself, but by the difference between its values in strong and weak electric fields. Coupling of FAIMS to conventional IMS and stacking of conventional IMS stages have enabled two-dimensional separations that dramatically expand the power of ion mobility methods.

  7. New and effective multi-element alpha-hematite systems for reduction of trichloroethylene.

    Science.gov (United States)

    Ghorpade, Praveen A; Kim, Jung-Hwan; Choi, Won-Ho; Park, Joo-Yang

    2014-01-01

    The reactivity of different alpha-hematite (alpha-Fe203) systems for dechlorination of trichloroethylene (TCE) in the presence of Fe(II) and CaO was investigated. Initially different experiments were conducted to investigate the reactivity of pure and doped alpha-Fe203. It was found that the presence of elements such as Si, Cu, and Mn in alpha-Fe203 had a significant effect on TCE reduction potential of alpha-Fe203; however, the reduction potential was less than that of alpha-Fe203 (Bayferrox- 110 M, used in a previous study). Further studies were carried out and alpha-Fe203 was synthesized in a manner similar to that of Bayferrox-110 M. This synthetic alpha-Fe203 showed improved reactivity and was found to follow pseudo-first-order kinetics when used in TCE reduction experiments. The preliminary end products analysis showed that TCE degradation was probably via beta-elimination pathway. Detailed investigations ofa-Fe203 systems were carried out using X-ray diffraction, X-ray fluorescence, and scanning electron microscopy with energy-dispersive spectrometry. The results demonstrated that the TCE reduction capacity of alpha-Fe203 was strongly dependent on the other elements present in iron powder used to synthesize alpha-Fe203. It was suspected that these multi-elements in alpha-Fe203 helped to improve its conduction property. Current findings suggest that alpha-Fe203 not in the pure but combined with other elements could be thought as a potential system for TCE reduction.

  8. Analysis of perfluoroalkyl substances in cord blood by turbulent flow chromatography coupled to tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Llorca, Marta; Perez, Francisca [Department of Environmental Chemistry, IDAEA-CSIC, Barcelona (Spain); Farre, Marinella, E-mail: mfuqam@cid.csic.es [Department of Environmental Chemistry, IDAEA-CSIC, Barcelona (Spain); Agramunt, Silvia [Centre for Research in Environmental Epidemiology (CREAL), Barcelona (Spain); IMIM (Hospital del Mar Research Institute), Barcelona (Spain); Kogevinas, Manolis [Centre for Research in Environmental Epidemiology (CREAL), Barcelona (Spain); IMIM (Hospital del Mar Research Institute), Barcelona (Spain); CIBER Epidemiologia y Salud Publica (CIBERESP), Barcelona (Spain); National School of Public Health, Athens (Greece); Barcelo, Damia [Department of Environmental Chemistry, IDAEA-CSIC, Barcelona (Spain); Catalan Institute for Water Research (ICRA), Girona (Spain); King Saud University, Riyadh (Saudi Arabia)

    2012-09-01

    A fast on-line analytical method based on turbulent flow chromatography (TFC) in combination with tandem mass spectrometry has been applied for the first time for the analysis of eighteen perfluoroalkyl substances (PFASs), in cord blood. A simple and rapid sample pre-treatment was optimised consisting on protein precipitation of 100 {mu}L of sample with acetonitrile (1:1) followed by centrifugation during 10 min. The method was adapted to be sensitive enough and robust with minimum sample injection volume requirements (20 {mu}L). The optimised methodology presented method limits of detection (MLOD) between 0.031 and 0.76 {mu}g/L, detection capabilities (CC{alpha}) in the range between 0.005 and 0.99 {mu}g/L and decision limits (CC{beta}) ranging from 0.006 to 1.16 {mu}g/L. The recoveries in blank blood were calculated by spiking experiments with a mixture of 18 PFASs and established between 70 and 126% for most of compounds. Isotopic dilution was carried out for quantification of selected analytes. In-house validation of this new approach was carried out according to the requirements in the 2002/657/EC Decision. Finally the good applicability of this new approach was proved by the analysis of 60 cord blood samples from two different Mediterranean cities, Barcelona (Spain) and Heraklion (Greece). Ions perfluorohexanesulfonate (PFHxS) and perfluorooctanesulfonate (PFOS) were found at highest concentration and the more frequently compounds were PFHxS, PFOS and perfluorooctanoic acid (PFOA). The newly developed method proved to be suitable for large-scale epidemiologic studies, and to the data on PFASs exposure during pregnancy. -- Highlights: Black-Right-Pointing-Pointer An on-line method has been developed for the analysis of 18 perfluoroalkyl substances. Black-Right-Pointing-Pointer The method is based on turbulent flow chromatography tandem mass spectrometry. Black-Right-Pointing-Pointer The method was applied in 60 cord blood samples from 2 Mediterranean cities

  9. Lack of co-ordinate expression of the alpha1(I) and alpha1(III) procollagen genes in fibroblast clonal cultures.

    Science.gov (United States)

    Yamaguchi, Y; Crane, S; Zhou, L; Ochoa, S M; Falanga, V

    2000-12-01

    Several extracellular matrix genes, most notably alpha1(I) and alpha1(III) procollagen, are reported to be co-ordinately expressed in cultures of dermal fibroblasts. However, it remains unclear whether the expression of these genes is truly co-ordinate or whether it may be the result of averaging the phenotypic expression of different fibroblast subpopulations present within each culture. Objectives To determine by Northern analysis the correlation between alpha1(I) and alpha1(III) procollagen mRNA levels in clonal populations of human dermal fibroblasts. As previously described, clonal cultures were derived from parent strains of human dermal fibroblasts by a microscopically controlled dilution technique and by stimulation of single cells with low oxygen tension in the early phases of clonal growth. In agreement with previous reports, we found that baseline steady-state levels of alpha1(I) procollagen mRNA were co-ordinately regulated with the alpha1(III) procollagen mRNA in 26 parent strains (r = 0. 9003; P ordinate regulation observed in non-clonal cultures, suggesting that these two genes operate under different sets of regulatory controls. This clonal heterogeneity may provide additional flexibility to the process of tissue repair and fibroblast clonal expansion.

  10. A probabilistic analysis of rapid boron dilution scenarios

    International Nuclear Information System (INIS)

    Kohut, P.; Diamond, D.J.

    1993-01-01

    A probabilistic and deterministic analysis of a rapid boron dilution scenario related to reactor restart was performed. The event is initiated by a loss of off-site power during the startup dilution process. The automatic restart of the charging pump in such cases may lead to the accumulation of a diluted slug of water in the lower plenum. The restart of the reactor coolant pumps may send the diluted slug through the core, adding sufficient reactivity to overcome the shutdown margin and cause a power excursion. The concern is that the power excursion is sufficient in certain circumstances to cause fuel damage. The estimated core damage frequency based on the scoping analysis is 1.0--3.0E-05/yr for the plants analyzed. These are relatively significant values when compared to desirable goals. The analysis contained assumptions related to plant specific design characteristics which may lead to non-conservative estimates. The most important conservative assumptions were that mixing of the injected diluted water is insignificant and that fuel damage occurs when the slug passes through the core

  11. Initial magnetic susceptibility of the diluted magnetopolymer elastic composites

    International Nuclear Information System (INIS)

    Borin, D.Yu.; Odenbach, S.

    2017-01-01

    In this work diluted magnetopolymer elastic composites based on magnetic microparticles are experimentally studied. Considered samples have varied concentration of the magnetic powder and different structural anisotropy. Experimental data on magnetic properties are accomplished by microstructural observations performed using X-Ray tomography. Influence of the particles amount and structuring effects on the initial magnetic susceptibility of the composites as well as the applicability of the Maxwell-Garnett approximation, which is widely used in considerations of magnetopolymer elastic composites, are evaluated. It is demonstrated that the approximation works well for diluted samples containing randomly distributed magnetic particles and for the diluted samples with chain-like structures oriented perpendicular to an externally applied field, while it fails to predict the susceptibility of the samples with structures oriented parallel to the field. Moreover, it is shown, that variation of the chains morphology does not significantly change the composite initial magnetic susceptibility. - Highlights: • The Maxwell-Garnet prediction works well for the diluted isotropic composites. • The Maxwell-Garnet prediction can be used for composites with structures oriented perpendicular to an applied field. • Chains oriented parallel to an applied field significantly increase the composite initial magnetic susceptibility. • The number and thickness of chains is not of the highest importance for the diluted composites. • The crucial reason of the observed effect is expected to be the demagnetisation factor of the chains.

  12. Mind Your p's and Alphas.

    Science.gov (United States)

    Stallings, William M.

    In the educational research literature alpha, the a priori level of significance, and p, the a posteriori probability of obtaining a test statistic of at least a certain value when the null hypothesis is true, are often confused. Explanations for this confusion are offered. Paradoxically, alpha retains a prominent place in textbook discussions of…

  13. Summary of Alpha Particle Transport

    Energy Technology Data Exchange (ETDEWEB)

    Medley, S.S.; White, R.B.; Zweben, S.J.

    1998-08-19

    This paper summarizes the talks on alpha particle transport which were presented at the 5th International Atomic Energy Agency's Technical Committee Meeting on "Alpha Particles in Fusion Research" held at the Joint European Torus, England in September 1997.

  14. A low-makeup beveled tip capillary electrophoresis /electrospray ionization mass spectrometry interface for micellar electrokinetic chromatography and nonvolatile buffer capillary electrophoresis.

    Science.gov (United States)

    Tseng, Mei-Chun; Chen, Yet-Ran; Her, Guor-Rong

    2004-11-01

    A robust interface has been developed for interfacing micellar electrokinetic chromatography (MEKC) and nonvolatile buffer capillary electrophoresis (CE) to electrospray ionization mass spectrometry (ESI-MS). The interface consists of two parallel capillaries for separation (50 microm i.d. x 155 microm o.d.) and makeup (50 microm i.d. x 155 microm o.d.) housed within a larger capillary (530 microm i.d. x 690 microm o.d.). The capillaries terminate in a single tapered tip having a beveled edge. The use of a tapered beveled edge results in a greater tip orifice diameter (75 microm) than in a previous design from our laboratory (25 microm) that used a flat tip. While maintaining a similar optimum flow rate and consequently similar sample dilution, a 75-microm beveled emitter is more rugged than a 25-microm flat tip. Furthermore, the incorporation of a sheath liquid capillary allows the compositions of the final spray solution to be controlled. The application of this novel CE/ESI-MS interface was demonstrated for MEKC using mixtures of triazines (positive ion mode) and phenols (negative ion mode). The ability to perform CE/ESI-MS using a nonvolatile buffer was demonstrated by the analysis of gangliosides with a buffer consisting of 40 mM borate and 20 mM alpha-cyclodextrin.

  15. Non‐diluted seawater enhances nasal ciliary beat frequency and wound repair speed compared to diluted seawater and normal saline

    Science.gov (United States)

    Bonnomet, Arnaud; Luczka, Emilie; Coraux, Christelle

    2016-01-01

    Background The regulation of mucociliary clearance is a key part of the defense mechanisms developed by the airway epithelium. If a high aggregate quality of evidence shows the clinical effectiveness of nasal irrigation, there is a lack of studies showing the intrinsic role of the different irrigation solutions allowing such results. This study investigated the impact of solutions with different pH and ionic compositions, eg, normal saline, non‐diluted seawater and diluted seawater, on nasal mucosa functional parameters. Methods For this randomized, controlled, blinded, in vitro study, we used airway epithelial cells obtained from 13 nasal polyps explants to measure ciliary beat frequency (CBF) and epithelial wound repair speed (WRS) in response to 3 isotonic nasal irrigation solutions: (1) normal saline 0.9%; (2) non‐diluted seawater (Physiomer®); and (3) 30% diluted seawater (Stérimar). The results were compared to control (cell culture medium). Results Non‐diluted seawater enhanced the CBF and the WRS when compared to diluted seawater and to normal saline. When compared to the control, it significantly enhanced CBF and slightly, though nonsignificantly, improved the WRS. Interestingly, normal saline markedly reduced the number of epithelial cells and ciliated cells when compared to the control condition. Conclusion Our results suggest that the physicochemical features of the nasal wash solution is important because it determines the optimal conditions to enhance CBF and epithelial WRS thus preserving the respiratory mucosa in pathological conditions. Non‐diluted seawater obtains the best results on CBF and WRS vs normal saline showing a deleterious effect on epithelial cell function. PMID:27101776

  16. Non-diluted seawater enhances nasal ciliary beat frequency and wound repair speed compared to diluted seawater and normal saline.

    Science.gov (United States)

    Bonnomet, Arnaud; Luczka, Emilie; Coraux, Christelle; de Gabory, Ludovic

    2016-10-01

    The regulation of mucociliary clearance is a key part of the defense mechanisms developed by the airway epithelium. If a high aggregate quality of evidence shows the clinical effectiveness of nasal irrigation, there is a lack of studies showing the intrinsic role of the different irrigation solutions allowing such results. This study investigated the impact of solutions with different pH and ionic compositions, eg, normal saline, non-diluted seawater and diluted seawater, on nasal mucosa functional parameters. For this randomized, controlled, blinded, in vitro study, we used airway epithelial cells obtained from 13 nasal polyps explants to measure ciliary beat frequency (CBF) and epithelial wound repair speed (WRS) in response to 3 isotonic nasal irrigation solutions: (1) normal saline 0.9%; (2) non-diluted seawater (Physiomer®); and (3) 30% diluted seawater (Stérimar). The results were compared to control (cell culture medium). Non-diluted seawater enhanced the CBF and the WRS when compared to diluted seawater and to normal saline. When compared to the control, it significantly enhanced CBF and slightly, though nonsignificantly, improved the WRS. Interestingly, normal saline markedly reduced the number of epithelial cells and ciliated cells when compared to the control condition. Our results suggest that the physicochemical features of the nasal wash solution is important because it determines the optimal conditions to enhance CBF and epithelial WRS thus preserving the respiratory mucosa in pathological conditions. Non-diluted seawater obtains the best results on CBF and WRS vs normal saline showing a deleterious effect on epithelial cell function. © 2016 The Authors International Forum of Allergy & Rhinology, published by ARSAAOA, LLC.

  17. Uptake of (3H)progesterone and (3H)5alpha-dihydroprogesterone by rat tissues in vivo and analysis of accumulated radioactivity: accumulation of 5alpha-dihydroprogesterone by pituitary and hypothalamic tissues.

    Science.gov (United States)

    Karavolas, H J; Hodges, D; O'Brien, D

    1976-01-01

    These in vivo studies explored the possibility that the metabolism of progesterone to 5alpha-dihydroprogesterone (5alpha-DHP) and 3alpha-hydroxy-5alpha-pregnan-20-one in hypothalamus and pituitary may influence gonadotropin release. [3H]progesterone or [3H]5alpha-DHP was injected iv into ovariectomized or ovariectomized-adrenalectomized rats for 10 0r 30 min. 3H content was determined for plasma, anterior pituitary, medial basal hypothalamus (MBH), cerebral cortex, muscle and uterus. Isotopic dilution analyses of the accumulated 3H were made for progesterone, 5alpha-DHP, 3alpha-hydroxy-5alpha-pregnan-20-one, 20alpha-dihydroprogesterone, 20alpha-hydroxy-5alpha-pregnan-3-one, and 5alpha-pregnane-3alpha, 20alpha-diol on samples from the 10 min groups. With progesterone injections, most of the tissue 3H was distributed among progesterone, 5alpha-DHP, and 3alpha-hydroxy-5alpha-pregnan-20-one. Progesterone was the predominant 3H-steroid in uterus, MBH, cerebral cortex and muscle. [3H]5alpha-DHP was the other major 3H-steroid in MBH and the predominant one in pituitary. In terms of tissue/plasma concentration comparisons, no tissue concentration of [3H]progesterone was greater than that in plasma except for MBH in the ovariectomized-adrenalectomized group. In contrast, [3H]5alpha-DHP levels in pituitary, MBH and cerebral cortex were many fold greater than those in plasma and muscle. MBH and pituitary levels were significantly greater than that in cerebral cortex. With 5alpha-DHP injections, most tissue 3H was associated with 5alpha-DHP and/or 3alpha-hydroxy-5alpha-pregnan-20-one. No [3H]progesterone was detected. [3H]5alpha-DHP predominated in pituitary and MBH, while 3alpha-hydroxy-5alpha-pregnan-20-one predominated in the others. In terms of tissue and plasma concentration comparisons, MBH, pituitary and cerebral cortical concentrations of [3H]5alpha-DHP were markedly higher than plasma, muscle, and uterine levels. Pituitary and MBH concentrations were also greater than

  18. Overexpression, purification, and characterization of recombinant barley alpha-amylases 1 and 2 secreted by the methylotrophic yeast Pichia pastoris

    DEFF Research Database (Denmark)

    Juge, N; Andersen, Jens S.; Tull, D

    1996-01-01

    Recombinant barley alpha-amylase isozymes 1 and 2 were secreted by Pichia pastoris at up to 50 and 1 mg/liter, respectively, representing approximately a 50-fold increase compared to the levels of the heterologous expression by Saccharomyces cerevisiae. The cDNA clones E or pM/C encoding isozymes 1...... with a value of 45,447 calculated from the sequence, liquid chromatography/mass spectrometry of endo Lys C-generated peptides followed by tandem mass spectrometry on a nanoelectrospray ionization/mass spectrometry/mass spectrometry system identified additional recombinant isozyme 1 forms to be glycosylated...... on Thr410, N-acetylated on His1, S-glutathionylated on Cys95, or C-terminally truncated of -412RS, -411QRS, and -410LQRS. The recombinant enzymes and the alpha-amylases from barley malt closely resembled each other in enzymatic activity on insoluble Blue Starch, amylose of degree of polymerization 17...

  19. Analytical applications of resonance ionization mass spectrometry (RIMS)

    International Nuclear Information System (INIS)

    Fassett, J.D.; Travis, J.C.

    1988-01-01

    A perspective on the role of resonance ionization mass spectrometry (RIMS) in the field of analytical chemistry is presented. RIMS provides new, powerful, and complementary capabilities relative to traditional methods of inorganic mass spectrometry. Much of the initial work in RIMS has been to illustrate these capabilities and define the potential of RIMS in the generalized field of chemical analysis. Three areas of application are reviewed here: (1) noble gas measurements; (2) materials analysis using isotope dilution (IDMS); and, (3) solids analysis using direct sampling. The role of RIMS is discussed relative to the more traditional mass spectrometric methods of analysis in these areas. The applications are meant to illustrate the present state-of-the-art as well as point to the future state-of-the-art of RIMS in chemical analysis. (author)

  20. Proteinaceous alpha-araylase inhibitors

    DEFF Research Database (Denmark)

    Svensson, Birte; Fukuda, Kenji; Nielsen, P.K.

    2004-01-01

    Proteins that inhibit alpha-amylases have been isolated from plants and microorganisms. These inhibitors can have natural roles in the control of endogenous a-amylase activity or in defence against pathogens and pests; certain inhibitors are reported to be antinutritional factors. The alpha-amylase...... inhibitors belong to seven different protein structural families, most of which also contain evolutionary related proteins without inhibitory activity. Two families include bifunctional inhibitors acting both on alpha-amylases and proteases. High-resolution structures are available of target alpha-amylases...... in complex with inhibitors from five families. These structures indicate major diversity but also some similarity in the structural basis of alpha-amylase inhibition. Mutational analysis of the mechanism of inhibition was performed in a few cases and various protein engineering and biotechnological...