The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
John S. Vogel - One of the best experts on this subject based on the ideXlab platform.
-
Analytical validation of Accelerator Mass Spectrometry for pharmaceutical development
Bioanalysis, 2010Co-Authors: Bradly D. Keck, Ted Ognibene, John S. VogelAbstract:The validation parameters for pharmaceutical analyses were examined for the Accelerator Mass Spectrometry measurement of 14C/C ratio, independent of chemical separation procedures. The isotope ratio measurement was specific (owing to the 14C label), stable across samples storage conditions for at least 1 year, linear over four orders of magnitude with an analytical range from 0.1 Modern to at least 2000 Modern (instrument specific). Furthermore, accuracy was excellent (between 1 and 3%), while precision expressed as coefficient of variation was between 1 and 6% determined primarily by radiocarbon content and the time spent analyzing a sample. Sensitivity, expressed as LOD and LLOQ was 1 and 10 attomoles of 14C, respectively (which can be expressed as compound equivalents) and for a typical small molecule labeled at 10% incorporated with 14C corresponds to 30 fg equivalents. Accelerator Mass Spectrometry provides a sensitive, accurate and precise method of measuring drug compounds in biological matrices.
-
Accelerator Mass Spectrometry for quantitative in vivo tracing.
Sustainability, 2005Co-Authors: John S. VogelAbstract:Accelerator Mass Spectrometry (AMS) counts individual rare, usually radio-, isotopes such as radiocarbon at high efficiency and specificity in milligram-sized samples. AMS traces very low chemical doses (micrograms) and radiative doses (100 Bq) of isotope-labeled compounds in animal models and directly in humans for pharmaceutical, nutritional, or toxicological research. Absorption, metabolism, distribution, binding, and elimination are all quantifiable with high precision after appropriate sample definition.
-
Neuroscience and Accelerator Mass Spectrometry.
Journal of mass spectrometry : JMS, 2005Co-Authors: Magnus Palmblad, Bruce A. Buchholz, Darren J. Hillegonds, John S. VogelAbstract:Accelerator Mass Spectrometry (AMS) is a Mass spectrometric method for quantifying rare isotopes. It has had great impact in geochronology and archaeology and is now being applied in biomedicine. AMS measures radioisotopes such as {sup 3}H, {sup 14}C, {sup 26}Al, {sup 36}Cl and {sup 41}Ca, with zepto- or attomole sensitivity and high precision and throughput, enabling safe human pharmacokinetic studies involving: microgram doses, agents having low bioavailability, or toxicology studies where administered doses must be kept low (
-
Technetium measurements by Accelerator Mass Spectrometry at LLNL
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2000Co-Authors: B.a Bergquist, J.e. Mcaninch, A. A. Marchetti, R. E. Martinelli, G. J. Nimz, I.d. Proctor, John Southon, John S. VogelAbstract:Technetium-99 is a long-lived, high-abundance fission product which has been widely distributed in the environment through atmospheric testing, the nuclear fuel cycle, and nuclear medicine. It has a high potential for migration in the environment as the pertechnetate anion. At the Center for Accelerator Mass Spectrometry, methods are being developed for the detection of this radionuclide by Accelerator Mass Spectrometry (AMS), including extraction from environmental samples, concentration and purification of the 99Tc, conversion to a form appropriate for AMS analysis, and quantification by AMS. Besides interference from the stable (though relatively rare) atomic isobar 99Ru, the detection of 99Tc by AMS presents some technical challenges which are not present for the other radionuclides typically measured by AMS. These challenges are related to the lack of a stable Tc isotope. Here we present the status of our 99Tc methods including discussion of interferences and sensitivity, and recent results for environmental samples and the IAEA reference material IAEA-381, Irish Sea Water. Sensitivity is presently ∼10 μBq (∼1×108 atoms) per sample, limited primarily by 99Ru introduced from process chemicals, and precision/reproducibility is ∼15–25%.
-
Accelerator Mass Spectrometry as a bioanalytical tool
1997Co-Authors: John S. VogelAbstract:This paper presents data that supports Accelerator Mass Spectrometry (AMS) as a valid bioanalytical tool for tracing long lived radioisotopes in uses as molecular labels or elemental tracers.
X.-l. Zhao - One of the best experts on this subject based on the ideXlab platform.
-
Determination of 135Cs by Accelerator Mass Spectrometry
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2015Co-Authors: C. M. Macdonald, William E. Kieser, X.-l. Zhao, C. R. J. Charles, R.j. Cornett, A.e. LitherlandAbstract:Abstract The ratio of anthropogenic 135 Cs and 137 Cs isotopes is characteristic of a uranium fission source. This research evaluates the technique of isotope dilution (yield tracing) for the purpose of quantifying 135 Cs by Accelerator Mass Spectrometry with on-line isobar separation. Interferences from Ba, Zn 2 , and isotopes of equal Mass to charge ratios were successfully suppressed. However, some sample crosstalk from source contamination remains. The transmission and di-fluoride ionization efficiencies of Cs isotopes were found to be 8 × 10 −3 and 1.7 × 10 −7 respectively. This quantification of 135 Cs using yield tracing by Accelerator Mass Spectrometry shows promise for future environmental sample analysis once the issues of sample crosstalk and low efficiency can be resolved.
-
isobar separation at low energy in Accelerator Mass Spectrometry
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2004Co-Authors: Jonathan P. Doupe, A.e. Litherland, Ilia Tomski, X.-l. ZhaoAbstract:The use of ion reactions at keV and eV energies for atomic or molecular isobar separation with applications in Accelerator Mass Spectrometry (AMS) is discussed briefly. It is shown that by a combination of techniques, isobar suppression may be extended to additional rare radioactive isotopes.
-
Observation of Yb- by Accelerator Mass Spectrometry
Journal of Physics B: Atomic Molecular and Optical Physics, 1991Co-Authors: A.e. Litherland, Linas R. Kilius, M. J. Nadeau, M.a. Garwan, X.-l. ZhaoAbstract:Negative ions of Yb have been observed for the first time using high-resolution heavy-ion Accelerator Mass Spectrometry to remove the intense molecular interferences. The existence of stable negative ions of this element has been predicted recently.
Walter Kutschera - One of the best experts on this subject based on the ideXlab platform.
-
Accelerator Mass Spectrometry: state of the art and perspectives
Advances in Physics: X, 2016Co-Authors: Walter KutscheraAbstract:Accelerator Mass Spectrometry (AMS) is sometimes called ‘the art of counting atoms one by one’. In addition to counting individual atoms, AMS is also capable to determine both Mass number (A) and a...
-
Accelerator Mass Spectrometry – from DNA to astrophysics
EPJ Web of Conferences, 2013Co-Authors: Walter KutscheraAbstract:A brief review of Accelerator Mass Spectrometry (AMS) is presented. The present work touches on a few technical aspects and recent developments of AMS, and describes two specific applications of AMS, the dating of human DNA with the 14 C bomb peak and the search for superheavy elements in nature. Since two extended general reviews on technical developments in AMS [1] and applications of AMS [2] will appear in 2013, frequent reference to these reviews is made.
-
Applications of Accelerator Mass Spectrometry
International Journal of Mass Spectrometry, 2013Co-Authors: Walter KutscheraAbstract:Abstract Applications of Accelerator Mass Spectrometry (AMS) evolved into multi-disciplinary research covering virtually every domain of our environment at large. The possibilities of applications are clearly coupled to technical developments of AMS, which will be covered by the accompanying article of H.-A. Synal. The present review therefore concentrates on describing AMS applications to the largest extent possible. Since the knowledge of the author on the many fields where AMS measurements are performed is, of course, limited, the selection of examples discussed in this review is somewhat biased. In order to compensate for this, a rather long list of references is presented, which should be consulted for a deeper understanding of the respective fields. The seven domains of our environment at large (atmosphere, biosphere, hydrosphere, cryosphere, lithosphere, cosmosphere, and technosphere) are being used as a guideline for the present review.
-
Accelerator Mass Spectrometry at VERA
2000Co-Authors: Walter KutscheraAbstract:The Vienna Environmental Research Accelerator (VERA) is a dedicated facility for Accelerator Mass Spectrometry (AMS), operated at the University of Vienna since 1996. The principle of AMS with VERA and the advantage of measuring long-lived radioisotopes by atom counting (AMS) rather than decay counting (s decay) is described. A brief overview on AMS applications is also presented.
-
Accelerator Mass Spectrometry-big and small
The eighth international conference on heavy-ion accelerator technology, 1999Co-Authors: Walter KutscheraAbstract:A brief review of the current status of Accelerator Mass Spectrometry is presented, with emphasis on some of the most recent technical developments.
Mark L. Roberts - One of the best experts on this subject based on the ideXlab platform.
-
A gas-accepting ion source for Accelerator Mass Spectrometry: Progress and applications
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2013Co-Authors: Mark L. Roberts, Karl F. Von Reden, Cameron Mcintyre, Joshua R. Burton, Steven R. BeaupréAbstract:The National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility at the Woods Hole Oceanographic Institution has developed an Accelerator Mass Spectrometry (AMS) system designed specifically for the analysis of 14C in a continuously flowing stream of carrier gas. A key part of the system is a gas-accepting microwave ion source. Recently, substantial progress has been made in the development of this source, having achieved ion currents rivaling that of a traditional graphite source (albeit at relatively low efficiency). Details and present performance of the gas source are given. Additionally, representative results obtained from coupling the source to both a gas chromatograph and gas bench are presented.
-
Design and reality: Continuous-flow Accelerator Mass Spectrometry (CFAMS)
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2011Co-Authors: Karl F. Von Reden, Mark L. Roberts, Cameron Mcintyre, Joshua R. BurtonAbstract:Abstract In 2007 we published [1] the design of a novel Accelerator Mass Spectrometry (AMS) system capable of analyzing gaseous samples injected continuously into a microwave plasma gas ion source. Obvious advantages of such a system are drastically reduced processing times and avoidance of potentially contaminating chemical preparation steps. Another paper in these proceedings will present the progress with the development of the microwave gas ion source that has since been built and tested at the National Ocean Sciences AMS Facility in Woods Hole [2] . In this paper we will review the original design and present updates, reflecting our recent encouraging experience with the system. A simple summary: large acceptance ion beam optics design is beneficial to Accelerator Mass Spectrometry in general, but essential to AMS with plasma gas ion sources.
-
A High-Performance 14C Accelerator Mass Spectrometry System
Radiocarbon, 2010Co-Authors: Mark L. Roberts, Karl F. Von Reden, Cameron Mcintyre, Joshua R. Burton, K.l. Elder, Brett E. Longworth, B.x. Han, Brad E. Rosenheim, William J. Jenkins, E GalutschekAbstract:A new and unique radiocarbon Accelerator Mass Spectrometry (AMS) facility has been constructed at the Woods Hole Oceanographic Institution. The defining characteristic of the new system is its large-gap optical elements that provide a larger-than-standard beam acceptance. Such a system is ideally suited for high-throughput, high-precision measurements of 14C. Details and performance of the new system are presented.
-
Use of tritium Accelerator Mass Spectrometry for tree ring analysis.
Environmental science & technology, 2002Co-Authors: Adam H. Love, Mark L. Roberts, John Southon, James R. Hunt, ‖ And Marina L. Chiarappa-zucca, Karen H. DingleyAbstract:Public concerns over the health effects associated with low-level and long-term exposure to tritium released from industrial point sources have generated the demand for better methods to evaluate historical tritium exposure levels for these communities. The cellulose of trees accurately reflects the tritium concentration in the source water and may contain the only historical record of tritium exposure. The tritium activity in the annual rings of a tree was measured using Accelerator Mass Spectrometry to reconstruct historical annual averages of tritium exposure. Milligram-sized samples of the annual tree rings from a Tamarix located at the Nevada Test Site are used for validation of this methodology. The salt cedar was chosen since it had a single source of tritiated water that was well-characterized as it varied over time. The decay-corrected tritium activity of the water in which the salt cedar grew closely agrees with the organically bound tritium activity in its annual rings. This demonstrates that the milligram-sized samples used in tritium Accelerator Mass Spectrometry are suited for reconstructing anthropogenic tritium levels in the environment.
A.e. Litherland - One of the best experts on this subject based on the ideXlab platform.
-
Determination of 135Cs by Accelerator Mass Spectrometry
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2015Co-Authors: C. M. Macdonald, William E. Kieser, X.-l. Zhao, C. R. J. Charles, R.j. Cornett, A.e. LitherlandAbstract:Abstract The ratio of anthropogenic 135 Cs and 137 Cs isotopes is characteristic of a uranium fission source. This research evaluates the technique of isotope dilution (yield tracing) for the purpose of quantifying 135 Cs by Accelerator Mass Spectrometry with on-line isobar separation. Interferences from Ba, Zn 2 , and isotopes of equal Mass to charge ratios were successfully suppressed. However, some sample crosstalk from source contamination remains. The transmission and di-fluoride ionization efficiencies of Cs isotopes were found to be 8 × 10 −3 and 1.7 × 10 −7 respectively. This quantification of 135 Cs using yield tracing by Accelerator Mass Spectrometry shows promise for future environmental sample analysis once the issues of sample crosstalk and low efficiency can be resolved.
-
isobar separation at low energy in Accelerator Mass Spectrometry
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2004Co-Authors: Jonathan P. Doupe, A.e. Litherland, Ilia Tomski, X.-l. ZhaoAbstract:The use of ion reactions at keV and eV energies for atomic or molecular isobar separation with applications in Accelerator Mass Spectrometry (AMS) is discussed briefly. It is shown that by a combination of techniques, isobar suppression may be extended to additional rare radioactive isotopes.
-
Observation of Yb- by Accelerator Mass Spectrometry
Journal of Physics B: Atomic Molecular and Optical Physics, 1991Co-Authors: A.e. Litherland, Linas R. Kilius, M. J. Nadeau, M.a. Garwan, X.-l. ZhaoAbstract:Negative ions of Yb have been observed for the first time using high-resolution heavy-ion Accelerator Mass Spectrometry to remove the intense molecular interferences. The existence of stable negative ions of this element has been predicted recently.
