TY - JOUR T1 - 14C Blank Corrections for 25–100 μg Samples at the National Ocean Sciences AMS Laboratory JF - Radiocarbon Y1 - 2019 A1 - Roberts, M. L. A1 - Elder, K. L. A1 - Jenkins, W. J. A1 - Gagnon, A. R. A1 - Xu, L. A1 - Hlavenka, J. D. A1 - Longworth, B. E. KW - AMS KW - AMS dating KW - blank corrections AB - Replicate radiocarbon (14C) measurements of organic and inorganic control samples, with known Fraction Modern values in the range Fm = 0–1.5 and mass range 6 μg–2 mg carbon, are used to determine both the mass and radiocarbon content of the blank carbon introduced during sample processing and measurement in our laboratory. These data are used to model, separately for organic and inorganic samples, the blank contribution and subsequently “blank correct” measured unknowns in the mass range 25–100 μg. Data, formulas, and an assessment of the precision and accuracy of the blank correction are presented. VL - 61 SN - 0033-8222, 1945-5755 UR - https://www.cambridge.org/core/journals/radiocarbon/article/14c-blank-corrections-for-25100-g-samples-at-the-national-ocean-sciences-ams-laboratory/494B9CF72445198570213B4A2CC303D0 IS - 5 ER - TY - JOUR T1 - Comparison of large and ultra-small delta c-14 measurements in core top benthic foraminifera from the Okhotsk Sea JF - Radiocarbon Y1 - 2015 A1 - Keigwin, L. D. A1 - Gagnon, A. R. AB - The radiocarbon activity of benthic foraminifera was investigated in surface sediments from a high deposition rate location at a depth of 1000 m in the Okhotsk Sea. Sediments were preserved and stained with Rose Bengal to identify foraminifera that contain cytoplasm. The benthic fauna at this site is dominated by large specimens of Uvigerina peregrina, and bulk samples (similar to 150 individuals) of stained and unstained specimens were dated. The stained sample was about 240 C-14 yr younger than the unstained, and the presence of bomb C-14 is inferred by comparison to water column data in the nearby open North Pacific. Using new methods, multiple measurements were also made on samples of three stained and unstained individuals (as small as 7 mu g C). Results are consistent with those from the bulk samples. This suggests that similar ultra-small measurements could be made at other locations to reveal the age distribution of individuals in a sediment sample in order to assess the extent of bioturbation and the presence of bomb C-14 contamination. VL - 57 IS - 1 N1 - PT: J; TC: 1; UT: WOS:000351052600010 JO - Comparison of large and ultra-small delta c-14 measurements in core top benthic foraminifera from the Okhotsk Sea ER - TY - JOUR T1 - The NOSAMS sample preparation laboratory in the next millenium: Progress after the WOCE program JF - Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms Y1 - 2000 A1 - Gagnon, A. R. A1 - McNichol, A. P. A1 - Donoghue, J. C. A1 - Stuart, D. R. A1 - von Reden, K. AB - Since 1991, the primary charge of the National Ocean Sciences AMS (NOSAMS) facility at the Woods Hole Oceanographic Institution has been to supply high throughput, high precision AMS C-14 analyses for seawater samples collected as part of the World Ocean Circulation Experiment (WOCE). Approximately 13,000 samples taken as part of WOCE should be fully analyzed by the end of Y2K. Additional sample sources and techniques must be identified and incorporated if NOSAMS is to continue in its present operation mode.A trend in AMS today is the ability to routinely process and analyze radiocarbon samples that contain tiny amounts (<100 g) of carbon. The capability to mass-produce small samples for C-14 analysis has been recognized as a major facility goal. The installation of a new 134-position MC-SNICS ion source, which utilizes a smaller graphite target cartridge than presently used, is one step towards realizing this goal. New preparation systems constructed in the sample preparation laboratory (SPL) include an automated bank of 10 small-volume graphite reactors, an automated system to process organic carbon samples, and a multi-dimensional preparative capillary gas chromatograph (PCGC). (C) 2000 Elsevier Science B.V. All rights reserved. VL - 172 IS - 172 N1 - 372jrTimes Cited:20Cited References Count:12 JO - The NOSAMS sample preparation laboratory in the next millenium: Progress after the WOCE program ER - TY - JOUR T1 - Oceanic uptake of CO2 re-estimated through d13C in WOCE samples JF - Nuclear Instruments and Methods in Physics Research Y1 - 2000 A1 - Lerperger, M. A1 - McNichol, A. P. A1 - Peden, J. A1 - Gagnon, A. R. A1 - Elder, K. L. A1 - Kutschera, W. A1 - Rom, W. A1 - Steier, P. VL - B (172) IS - 1-4 N1 - id: 1817 ER - TY - CONF T1 - The radiocarbon gradient at the Antarctic Polar Front T2 - AGU Ocean Sciences Meeting Y1 - 2000 A1 - Schneider, R. J. A1 - McNichol, A. P. A1 - von Reden, K. F. A1 - Elder, K. L. A1 - Gagnon, A. R. A1 - Key, R. M. A1 - Quay, P. D. A1 - Schlosser, P. M. JF - AGU Ocean Sciences Meeting CY - San Antonio, TX N1 - id: 317 ER - TY - CONF T1 - Ten years after - the WOCE AMS radiocarbon program T2 - Accelerator Mass Spectrometer Conference Y1 - 2000 A1 - McNichol, A. P. A1 - Schneider, R. J. A1 - von Reden, K. F. A1 - Gagnon, A. R. A1 - Elder, K. L. A1 - Key, R. M. A1 - Quay, P. D. JF - Accelerator Mass Spectrometer Conference N1 - id: 316 ER - TY - JOUR T1 - Ten years after - The WOCE AMS radiocarbon program JF - Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms Y1 - 2000 A1 - McNichol, A. P. A1 - Schneider, R. J. A1 - von Reden, K. F. A1 - Gagnon, A. R. A1 - Elder, K. L. A1 - Key, R. M. A1 - Quay, P. D. AB - The National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Facility is measuring all of the samples collected as part of the US WOCE Program - over 13,000 samples. We designed our extraction lines so that we also measure precise, oceanographically useful delta C-13-Sigma CO2 values. We have completed the analysis of samples from the Pacific and Southern Oceans and are processing those from the Indian Ocean now. At present, this constitutes the world's largest AMS data set. Reviews of the Pacific radiocarbon data are available and demonstrate the increased penetration of the "bomb signal" into the water column since the 1970s. Stable isotope data are being combined with those collected as part of NOAA's Ocean-Atmosphere Carbon Exchange Study to study the ocean's role in the anthropogenic CO2 cycle. The relationship of delta C-13 to other chemical tracers, e.g., PO4, O-2 and chlorofluorocarbons, will further our understanding of basic oceanographic processes. We present preliminary results from these studies as well as investigate the relationship of C-14 to C-13 in the ocean. (C) 2000 Elsevier Science B.V. All rights reserved. VL - 172 IS - 1-4 N1 - 372jrTimes Cited:14Cited References Count:12 JO - Ten years after - The WOCE AMS radiocarbon program ER - TY - CONF T1 - Installation and First Results of a 134-Sample MC-SNICS Ion Source at NOSAMS T2 - 8th International Conference on Accelerator Mass Spectrometry Y1 - 1999 A1 - von Reden, K. F. A1 - Schneider, R. J. A1 - McNichol, A. P. A1 - Elder, K. F. A1 - Gagnon, A. R. JF - 8th International Conference on Accelerator Mass Spectrometry CY - Vienna, Austria N1 - id: 1802 ER - TY - JOUR T1 - Evaluating reproducibility of seawater, inorganic and organic carbon 14C results at the National Ocean Sciences AMS Facility (NOSAMS) JF - Radiocarbon Y1 - 1998 A1 - Elder, K. L. A1 - McNichol, A. P.
 A1 - Gagnon, A. R. VL - 40 IS - 1 ER - TY - CONF T1 - High-precision Measurements of 14C as a Circulation Tracer in the Pacific, Indian, and Southern Oceans with Accelerator Mass Spectrometry (AMS) T2 - 8th International Conference on Heavy Ion Accelerator Technology Y1 - 1998 A1 - von Reden, K. F. A1 - Peden, J. C. A1 - Schneider, R. J. A1 - Bellino, M. A1 - Donoghue, J. A1 - Elder, K. L. A1 - Gagnon, A. R. A1 - Long, P. A1 - McNichol, A. P. A1 - Morin, T. A1 - Stuart, D. A1 - Hayes, J. M. A1 - Key, R. M. ED - Shepard, K. American Institute of Physics JF - 8th International Conference on Heavy Ion Accelerator Technology CY - Argonne National Lab N1 - id: 1636 ER - TY - CONF T1 - The NOSAMS Sample Preparation Laboratory: Systems and graphite performance analysis T2 - 16th International 14C Conference Y1 - 1998 A1 - Gagnon, A. R. A1 - McNichol, A. P. A1 - Donaghue, J. C. A1 - Morin, T. J. A1 - Peden, J. C. JF - 16th International 14C Conference CY - Groninghen N1 - id: 1628 ER - TY - CONF T1 - Reproducibility of seawater, inorganic and organic 14C results at NOSAMS T2 - Sixteenth International 14C Conference Y1 - 1998 A1 - Elder, K. L. A1 - McNichol, A. P. A1 - Gagnon, A. R. JF - Sixteenth International 14C Conference CY - Groningen VL - 40(1) N1 - id: 1625 ER - TY - JOUR T1 - Status Report of the National Ocean Sciences AMS Facility at Woods Hole Oceanographic Institution: Operations and Recent Developments JF - 15th International Conference on the Applications of Accelerators in Research and Industry Y1 - 1998 A1 - Bellino, M. A1 - von Reden, K. F. A1 - Schneider, R. J. A1 - Peden, J. C. A1 - Donoghue, J. A1 - Elder, K. L. A1 - Gagnon, A. R. A1 - Long, P. A1 - McNichol, A. P. A1 - Odegaard, A. P. A1 - Stuart, D. A1 - Handwork, S. A1 - Hayes, J. M. VL - A.I.P. Conference Proceedings IS - 475, part 2 N1 - id: 1647 ER - TY - CONF T1 - AMS measurements of the 14C distribution in the Pacific Ocean T2 - Proceedings of the Seventh International Conference on Accelerator Mass Spectrometry Y1 - 1997 A1 - von Reden, K. F. A1 - McNichol, A. P. A1 - Peden, J. C. A1 - Elder, K. L. A1 - Gagnon, A. R. A1 - Schneider, R. J. ED - Jull, A. J. T. JF - Proceedings of the Seventh International Conference on Accelerator Mass Spectrometry CY - Tucson, AZ VL - B123 N1 - id: 1644; B123 ER - TY - JOUR T1 - AMS measurements of the 14C distribution in the Pacific Ocean JF - Nuclear Instruments and Methods in Physics Research Y1 - 1997 A1 - von Reden, K. F. A1 - McNichol, A. P. A1 - Peden, J. C. A1 - Elder, K. L. A1 - Gagnon, A. R. A1 - Schneider, R. J. VL - B123 N1 - id: 1673 ER - TY - CONF T1 - Evaluating reproducibility of seawater, inorganic and organic carbon 14C results at the National Ocean Sciences AMS Facility (NOSAMS) T2 - 16th International Radiocarbon Conference Y1 - 1997 A1 - Elder, K. L. A1 - McNichol, A. P. A1 - Gagnon, A. R. JF - 16th International Radiocarbon Conference T3 - Book of Abstracts CY - Groningen N1 - id: 956 ER - TY - CONF T1 - The National Ocean Sciences AMS (NOSAMS) Sample Preparation Laboratory: Systems and Graphite Performance Analysis T2 - International Radiocarbon Conference Y1 - 1997 A1 - Gagnon, A. R. A1 - McNichol, A. P. A1 - Donoghue, J. C. A1 - Morin, T. J. A1 - Peden, J. C. JF - International Radiocarbon Conference CY - Groningen, Nethlands N1 - id: 962 ER - TY - CONF T1 - The NOSAMS sample preparation laboratory: overview of systems and techniques T2 - 16th International Radiocarbon Conference Y1 - 1997 A1 - Gagnon, A. R. A1 - McNichol, A. A1 - Donoghue, J. C. A1 - Merkle, K. M. A1 - Morin, T. J. JF - 16th International Radiocarbon Conference PB - Book of Abstracts CY - Groningen N1 - id: 955 ER - TY - CONF T1 - Reproducibility of 14C AMS analyses at NOSAMS T2 - 16th International Radiocarbon Conference Y1 - 1997 A1 - Elder, K. L. A1 - Gagnon, A. R. A1 - McNichol, A. P. JF - 16th International Radiocarbon Conference PB - Book of Abstracts CY - Groningen N1 - id: 961 ER - TY - JOUR T1 - Automated systems and techniques utilized at the NOSAMS sample preparation laboratory: An update of productivity and quality issues JF - Radiocarbon Y1 - 1996 A1 - Gagnon, A. R. A1 - McNichol, A. P. A1 - Hutton, D. L. A1 - Osborne, E. A. A1 - Donoghue, J. C. VL - 38 IS - 1 N1 - id: 959 ER - TY - CONF T1 - Improvements in procedural blanks at NOSAMS: Reflections of improvements in sample preparation and accelerator operation T2 - 15th International 14C Conference Y1 - 1995 A1 - McNichol, A. P. A1 - Gagnon, A. R. A1 - Osborne, E. a A1 - Hutton, D. L. A1 - von Reden, K. F. A1 - Schneider, R. J. JF - 15th International 14C Conference PB - Radiocarbon VL - 37 N1 - id: 1641; 15th International Radiocarbon Conference, Glasgow, Scotland, August 15-19, 1994 ER - TY - JOUR T1 - Improvements in procedural blanks at NOSAMS: Reflections of improvements in sample preparation and accelerator operation JF - Radiocarbon Y1 - 1995 A1 - McNichol, A. P. A1 - Gagnon, A. R. A1 - Osborne, E. A. A1 - Hutton, D. L. A1 - vonReden, K. F. A1 - Schneider, R. J. KW - SPECTROMETRY AB - During the four years the Sample Preparation Laboratory (SPL) at the National Ocean Sciences Accelerator Mass Spectrometer (NOSAMS) Facilty has been in operation we have accumulated much data from which we can assess our progress. We evaluate our procedural blanks here and describe modifications in our procedures that have improved our analyses of older samples. In the SPL, we convert three distinct types of samples-seawater, CaCO3 and organic carbon-to CO2 prior to preparing graphite for the accelerator and have distinct procedural blanks for each procedure. Dissolved inorganic carbon (Sigma CO2) is extracted from acidified seawater samples by sparging with a nitrogen carrier gas. We routinely analyze ''line blanks'' by processing CO2 from a C-14-dead source through the entire stripping procedure. Our hydrolysis blank, IAEA C-1, is prepared by acidifying in vacuo with 100% H3PO4 at 60 degrees C overnight, identical to our sample preparation. We use a dead graphite, NBS-21, or a commercially available carbon powder for our organic combustion blank; organic samples are combusted at 850 degrees C for 5 h using CuO to provide the oxidant. Analysis of our water stripping data suggests that one step in the procedure contributes the major portion of the line blank. At present, the contribution from the line blank has no effect on our seawater analyses (fraction modern (fm) between 0.7 and 1.2). Our hydrolysis blanks can have an fm value as low as 0.0006, but are more routinely between 0.0020 and 0.0025. The fm of our best organic combustion blanks is higher than those routinely achieved in other laboratories and we are currently altering our methods to reduce it. VL - 37 SN - 0033-8222 IS - 2 N1 - Ud868Times Cited:16 Cited References Count:6 JO - Radiocarbon ER - TY - JOUR T1 - Automated Sample Processing at the National Ocean Sciences Ams Facility JF - Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms Y1 - 1994 A1 - Cohen, G. J. A1 - Hutton, D. L. A1 - Osborne, E. A. A1 - vonReden, K. F. A1 - Gagnon, A. R. A1 - McNichol, A. P. A1 - Jones, G. A. AB - The high throughput and high precision requirements for the NOSAMS facility have made it essential to automate many of the stages in sample processing. These automated procedures increase the sample capacity for the lab while reducing errors in sample preparation. Automation has also allowed sample histories to be recorded and saved in Sybase, a relational data base. VL - 92 IS - 1-4 N1 - Nv547Times Cited:9Cited References Count:1 JO - Automated Sample Processing at the National Ocean Sciences Ams Facility ER - TY - JOUR T1 - High-precision AMS radiocarbon measurements of central Arctic Ocean seawaters JF - Nuclear Instruments and Methods in Physics Research Y1 - 1994 A1 - Jones, G. A. A1 - Gagnon, A. R. A1 - Schneider, R. J. A1 - von Reden, K. F. A1 - McNichol, A. P. VL - B92 N1 - id: 52 ER - TY - JOUR T1 - Internal and External Checks in the Nosams Sample Preparation Laboratory for Target Quality and Homogeneity JF - Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms Y1 - 1994 A1 - Osborne, E. A. A1 - McNichol, A. P. A1 - Gagnon, A. R. A1 - Hutton, D. L. A1 - Jones, G. A. AB - In the NOSAMS sample preparation laboratory (SPL) we have developed rigorous internal procedures aimed at ensuring that sample preparation introduces as little error into our analyses as possible and identifying problems rapidly. Our three major CO2 preparation procedures are: stripping inorganic carbon from seawater, hydrolyzing CaCO3, and oxidizing organic matter. For seawater, approximately 10% of our analyses are standards or blanks which we use to demonstrate extraction of virtually all the inorganic carbon. Analysis of the stable carbon isotopic composition of the CO2 extracted from our standards indicates a precision of better than 0.15-0.20 parts per thousand. We also routinely process C-14-free CO2 in our stripping lines to demonstrate the absence of a significant process-dependent blank. For organic combustions and CaCO3 hydrolyses, we use the carbon yield (% organic carbon (OC) or % CaCO3 by weight) as a check on our sample procedures. We have analyzed the blank contribution of these procedures as a function of sample size. Our organic carbon blank is constant at approximately 0.4% modem for samples containing greater than 1 mg C and our carbonate blank is less than 0.2% modern for samples containing more than 0.5 mg C. We use a standard Fe/H-2 catalytic reduction to prepare graphite from CO2. We check the completeness of our reactions with the pressure data stored during the reaction as well as use a robot to determine a gravimetric yield. All graphite undergoes a visual inspection and is rejected if any heterogeneities are present. We have recombusted graphite made from CO2 with deltaC-13 values ranging from -42 to 1 parts per thousand and determined that the deltaC-13 of the recombusted carbon agrees with that from the pure gas to within 0.05 parts per thousand, demonstrating little or no fractionation during the treatment of the sample. The deltaC-13 we measure on the CO2 generated from more than 75% of our samples is compared to the deltaC-13 measured on the AMS as a further check of our procedures. As further external checks, we analyzed the International Atomic Energy Association (IAEA) samples during the establishment of our laboratory and are presently participating in the third international radiocarbon intercalibration (TIRI) exercise. VL - 92 IS - 1-4 N1 - Nv547Times Cited:14Cited References Count:5 JO - Internal and External Checks in the Nosams Sample Preparation Laboratory for Target Quality and Homogeneity ER - TY - JOUR T1 - Radiocarbon Chronology of Black-Sea Sediments JF - Deep-Sea Research Part I-Oceanographic Research Papers Y1 - 1994 A1 - Jones, G. A. A1 - Gagnon, A. R. AB - Accelerator Mass Spectrometer (AMS) radiocarbon analyses have been made on 102 samples from 12 sediment cores and 23 samples from two water column profiles. These materials, collected during the first leg of the 1988 joint U.S.-Turkish Black Sea Expedition, provide the most comprehensive radiocarbon chronology of Black Sea sediments vet attempted. Radiocarbon analyses from carefully collected box cores and a molluse shell collected live in 1931 suggest the prebomb surface waters had a DELTAC-14 value of -55 parts per thousand (460 years) and that the maximum detrital correction for radiocarbon ages of Unit I sediments is 580 years for the organic carbon and 260 years for the carbonate fractions. Evidence does not support the 1430-2000 year pre-bomb surface water and/or detrital corrections argued for in past studies. The best estimates for the age of the beginning of the final invasion of the coccolithophore Emiliania huxleyi (Unit 1/2 boundary of Ross and DEGENS, 1974, The Black Sea-geology, chemistry and biology, pp. 183-199) and the age of the first invasion of E. huxleyi (Unit I/II boundary of HAY et al., 1991, Deep-Sea Research, 38, S1211-S1235) are 1635 +/- 60 and 2720 +/- 160 years BP, respectively. Sapropel formation began at approximately 7540 +/- 130 years BP at all depths in the basin, a pattern in disagreement with those predicted by existing time-evolution models of sapropel formation for this basin. Our data suggest that the oxic-anoxic interface has remained relatively stable throughout the Holocene, is controlled largely by the physical oceanography of the basin, and has not evolved as assumed by previous workers. VL - 41 IS - 3 N1 - Nm252Times Cited:121Cited References Count:44 JO - Radiocarbon Chronology of Black-Sea Sediments ER - TY - JOUR T1 - Rapid analysis of seawater samples at the National Ocean Sciences Accelerator Mass Spectrometry Facility, Woods Hole, MA JF - Radiocarbon Y1 - 1994 A1 - McNichol, A. P. A1 - Jones, G. A. A1 - Hutton, D. L. A1 - Gagnon, A. R. A1 - Key, R. M. VL - 36 IS - 2 N1 - id: 305 ER - TY - JOUR T1 - The Rapid Preparation of Seawater Sigma-Co2 for Radiocarbon Analysis at the National Ocean Sciences Ams Facility JF - Radiocarbon Y1 - 1994 A1 - McNichol, A. P. A1 - Jones, G. A. A1 - Hutton, D. L. A1 - Gagnon, A. R. A1 - Key, R. M. KW - accelerator mass-spectrometry KW - C-14 KW - samples AB - We have established a laboratory for extracting Sigma CO2 from seawater samples for AMS analysis of the radiocarbon content. The seawater samples are collected at sea, poisoned and stored until analysis in the laboratory. Each sample is acidified; the inorganic carbon is stripped out as CO2 with an inert carrier gas and then converted to graphite. We present results for Buzzards Bay surface H2O and Na2CO3 standards that demonstrate we strip > 98% of inorganic carbon from seawater. Stable isotope analyses are performed to better than 0.2 parts per thousand, and the reproducibility of C-14 measurements on Buzzards Bay seawater is better than 13 parts per thousand. Finally, we compare data from samples collected in 1991 to those collected in the 1970s and to large volume samples. VL - 36 SN - 0033-8222 IS - 2 N1 - Pz926Times Cited:61 Cited References Count:14 JO - Radiocarbon ER - TY - JOUR T1 - Tic, Toc, Dic, Doc, Pic, Poc - Unique Aspects in the Preparation of Oceanographic Samples for C-14 Ams JF - Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms Y1 - 1994 A1 - McNichol, A. P. A1 - Osborne, E. A. A1 - Gagnon, A. R. A1 - Fry, B. A1 - Jones, G. A. AB - The radiocarbon content of discrete carbon pools (total (T), dissolved (D), and particulate (P) inorganic (I) and organic (O) carbon (C)) is a useful tracer of carbon cycling within the modem and past ocean. The isolation of different carbon pools in the ocean environment and conversion to CO2 presents unique analytical problems for the radiocarbon chemist. In general, isolation and preparation of inorganic carbon presents few problems; dissolved carbon is easily extracted by acidifying the sample and stripping with an inert gas. Carbon is also readily isolated from particulate carbonate samples; in this case, CO2 is prepared by hydrolysis of the substrate with phosphoric acid. The isolation and preparation of organic carbon presents a much greater problem. Dissolved organic carbon (DOC) must first be isolated from DIC and then oxidized in the presence of very high salt concentrations. We present results from a closed-tube combustion method in which the DIC-free seawater is evaporated to dryness, transferred to a clean combustion tube, and oxidized overnight at 550-degrees-C. Combustion of total organic carbon (TOC) in sediments with a high inorganic carbon content is also difficult. Removal of CaCO3 with acid leaves severely deliquescent salts which, if not thoroughly dried, cause combustion tubes to explode. Removal of the salts by rinsing can also remove significant amounts of organic matter. Finally, we present results from a local coastal region. VL - 92 IS - 1-4 N1 - Nv547Times Cited:82Cited References Count:9 JO - Tic, Toc, Dic, Doc, Pic, Poc - Unique Aspects in the Preparation of Oceanographic Samples for C-14 Ams ER - TY - JOUR T1 - Ams-Graphite Target Production Methods at the Woods-Hole Oceanographic Institution during 1986-1991 JF - Radiocarbon Y1 - 1993 A1 - Gagnon, A. R. A1 - Jones, G. A. KW - accelerator mass-spectrometry KW - facility KW - ocean KW - radiocarbon KW - samples KW - sediments AB - In July 1986, an AMS radiocarbon target preparation laboratory was established at the Woods Hole Oceanographic Institution to produce graphite to be analyzed at the NSF-Accelerator Facility for Radioisotope Analysis at the University of Arizona (Tucson). By June 1991, 923 graphite targets had been prepared and 847 analyzed. Our lab procedures during this time included the careful documentation of weights of all starting samples, catalysts and final graphite yields, as well as the volume of CO2 gas evolved during CaCO3 hydrolysis or closed-tube organic carbon combustions. From these data, we evaluate the methods used in general and in our lab. VL - 35 SN - 0033-8222 IS - 2 N1 - Lg927Times Cited:12 Cited References Count:14 JO - Radiocarbon ER - TY - CONF T1 - Internal and external checks in the NOSAMS Sample Preparation Laboratory for target quality and homogeneity T2 - 6th International Conference on Accelerator Mass Spectrometry Y1 - 1993 A1 - McNichol, A. P. A1 - Gagnon, A. R. A1 - Osborne, E. A. A1 - Hutton, D. L. A1 - Jones, G. A. JF - 6th International Conference on Accelerator Mass Spectrometry CY - Canberra, Australia N1 - id: 958 ER - TY - CONF T1 - The National Ocean Sciences AMS Facility at Woods Hole Oceanographic Institution T2 - 6th International Conference on Accelerator Mass Spectrometry Y1 - 1993 A1 - Jones, G. A. A1 - Schneider, R. J. A1 - von Reden, K. F. A1 - McNichol, A. P. A1 - Gagnon, A. R. A1 - Cohen, G. J. A1 - Osborne, E. A. A1 - Hutton, D. L. A1 - Kessel, E. D. A1 - Elder, K. L. JF - 6th International Conference on Accelerator Mass Spectrometry CY - Canberra, Australia N1 - id: 930 ER - TY - JOUR T1 - Illumination of a Black-Box - Analysis of Gas-Composition during Graphite Target Preparation JF - Radiocarbon Y1 - 1992 A1 - McNichol, A. P. A1 - Gagnon, A. R. A1 - Jones, G. A. A1 - Osborne, E. A. KW - deposition AB - We conducted a study of relative gas composition changes of CO2, CO and CH4 during the formation of graphite targets using different temperatures, catalysts and methods. Reduction with H-2 increases the reaction rate without compromising the quality of the AMS target produced. Methane is produced at virtually any temperature, and the amount produced is greater at very low temperatures. The reduction of CO to graphite is very slow when H-2 is not included in the reaction. VL - 34 SN - 0033-8222 IS - 3 N1 - Kf389Times Cited:63 Cited References Count:10 JO - Radiocarbon ER - TY - CONF T1 - AMS radiocarbon results obtained from graphite targets produced at the Woods Hole Oceanographic Institution between 1986 and 1991 T2 - 14th Internation Radiocarbon Conference Y1 - 1991 A1 - Gagnon, A. R. A1 - Jones, G. A. JF - 14th Internation Radiocarbon Conference CY - Tucson, AZ N1 - id: 957 ER - TY - JOUR T1 - Illumination of a black box: Gas composition changes during graphite target preparation for AMS (Proceedings of the 14th International Radiocarbon Conference, 1991) JF - Radiocarbon Y1 - 1991 A1 - McNichol, A. P. A1 - Gagnon, A. R. A1 - Jones, G. A. A1 - Osborne, E. A. VL - 34 N1 - id: 1745 ER - TY - CONF T1 - The optimization of target production for AMS T2 - 14th International Radiocarbon Conference Y1 - 1991 A1 - McNichol, A. P. A1 - Gagnon, A. R. A1 - Jones, G. A. A1 - Schneider, R. J. A1 - von Reden, K. F. JF - 14th International Radiocarbon Conference CY - Tucson, AZ N1 - id: 922 ER -