scholarly journals 14C Background Levels in An Accelerator Mass Spectrometry System

Radiocarbon ◽  
1987 ◽  
Vol 29 (3) ◽  
pp. 323-333 ◽  
Author(s):  
J S Vogel ◽  
D E Nelson ◽  
J R Southon
Keyword(s):  
Mass Spectrometry ◽  
Late Pleistocene ◽  
Accelerator Mass Spectrometry ◽  
Measurement Precision ◽  
Small Samples ◽  
Present System ◽  
Total System ◽  
The Holocene ◽  
Anthracite Coal ◽  
Mass Spectrometry System

The levels and sources of the measurement background in an AMS 14C dating system have been studied in detail. The relative contributions to the total background from combustion, graphitization, storage, handling, and from the accelerator were determined by measuring the C concentrations in samples of anthracite coal ranging in size from 15μg to 20mg. The results show that, for the present system, the uncertainty in the background is greater than that due to measurement precision alone for very old or for very small samples. While samples containing 100μg of carbon can yield useful 14C dates throughout the Holocene, 200 to 500μg are required for dating late Pleistocene materials. With the identification of the procedures that introduce contamination, the level and uncertainty of the total system background should both be reducible to the point that 100μg of carbon would be sufficient for dating most materials.

scholarly journals Sample Dilution for AMS 14C Analysis of Small Samples (30–150 μg C)

Radiocarbon ◽  
2008 ◽  
Vol 50 (3) ◽  
pp. 413-436 ◽  
Author(s):  
M de Rooij ◽  
J van der Plicht ◽  
H A J Meijer
Keyword(s):  
Mass Spectrometry ◽  
Isotope Fractionation ◽  
Ice Core ◽  
Measurement Precision ◽  
Small Samples ◽  
Test Case ◽  
Routine Method ◽  
Optimum Conditions ◽  
Dilution Technique ◽  
Sample Dilution

We investigated sample dilution as a technique for accelerator mass spectrometry (AMS) radiocarbon analysis of very small samples (down to 30 μg). By diluting such samples up to a total weight of 200 μg, we can still perform reliable AMS measurements and improve the success rate significantly for targets that are difficult to measure. A disadvantage of this dilution technique is a loss of measurement precision. In addition, calculations of the 14C/12C isotope ratios and the uncertainties therein are not straightforward because of peculiarities in isotope fractionation processes in the AMS system. Therefore, to make sample dilution a routine method in our laboratory, we did extensive theoretical and experimental research to find the optimum conditions for all relevant parameters. Here, we report on the first detailed study dealing with all aspects of sample dilution. Our results can be applied in general. As an illustrative test case, we analyze 14C data for CO2 extracted from an ice core, from which samples of 35 μg C or less are available.

scholarly journals 10Be Analyses with a Compact AMS Facility—Are Bef2 Samples the Solution?

Radiocarbon ◽  
2004 ◽  
Vol 46 (1) ◽  
pp. 83-88 ◽  
Author(s):  
L Wacker ◽  
M Grajcar ◽  
S Ivy-Ochs ◽  
PW Kubik ◽  
M Suter
Keyword(s):  
Mass Spectrometry ◽  
Charge State ◽  
Accelerator Mass Spectrometry ◽  
Ionization Detector ◽  
Isobaric Interference ◽  
Rock Samples ◽  
Exposure Dating ◽  
Gas Ionization ◽  
Terminal Voltage ◽  
Mass Spectrometry System

The injection of 10BeF- instead of 10BeO- into a compact accelerator mass spectrometry system with a terminal voltage of 0.58 MV was investigated, because BF- molecules are unstable and isobaric interference of 10B with 10Be can thus be significantly reduced. We describe the method we developed to prepare BeF2 samples. 10Be was measured in a segmented gas ionization detector. Separation of 10Be from 10B could be achieved both for ions in the 1+ charge state with an energy of 0.8 MeV and in the 2+ charge state with an energy of 1.4 MeV. The 2+ ions are better separated, whereas the 1+ charge state has a higher transmission. 10Be/9Be ratios (~10-12) in a suite of rock samples were successfully determined for exposure dating in either charge state and compared with measurements made on the 6MV tandem.

scholarly journals The Chemical Preparation of AgCl for Measuring 36Cl in Polar Ice with Accelerator Mass Spectrometry

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 556-560 ◽  
Author(s):  
N J Conard ◽  
David Elmore ◽  
P W Kubik ◽  
H E Gove ◽  
L E Tubbs ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Accelerator Mass Spectrometry ◽  
Chemical Separation ◽  
Small Samples ◽  
Metal Powders ◽  
Separation And Purification ◽  
Polar Ice ◽  
Yield Data ◽  
Glacial Ice ◽  
Selection Of

A method of chemical separation and purification of chloride from relatively small samples (500 to 2100g) of glacial ice is presented. With this procedure the first successful measurements of pre-bomb levels of 36Cl in Greenland ice have been made. Emphasis is placed on methods of reducing sulfur, which causes interference in the accelerator mass spectrometry, and in maximizing the yield. Data regarding the selection of materials for sample holders and the use of metal powders for extending the lifetime of the sample are also presented.

scholarly journals Progress in Radiocarbon Target Preparation at the Antares AMS Centre

Radiocarbon ◽  
2001 ◽  
Vol 43 (2A) ◽  
pp. 275-282 ◽  
Author(s):  
Q Hua ◽  
G E Jacobsen ◽  
U Zoppi ◽  
E M Lawson ◽  
A A Williams ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Sample Preparation ◽  
Accelerator Mass Spectrometry ◽  
Sample Pretreatment ◽  
Small Samples ◽  
Sample Processing ◽  
Target Preparation ◽  
Recent Developments ◽  
Technical Details ◽  
Fe Reduction

We present routine methods of target preparation for radiocarbon analysis at the ANTARES Accelerator Mass Spectrometry (AMS) Centre, as well as recent developments which have decreased our procedural blank level and improved our ability to process small samples containing less than 200 μg of carbon. Routine methods of 14C sample preparation include sample pretreatment, CO2 extraction (combustion, hydrolysis and water stripping) and conversion to graphite (graphitization). A new method of cleaning glassware and reagents used in sample processing, by baking them under a stream of oxygen, is described. The results show significant improvements in our procedural blanks. In addition, a new graphitization system dedicated to small samples, using H2/Fe reduction of CO2, has been commissioned. The technical details of this system, the graphite yield and the level of fractionation of the targets are discussed.

scholarly journals Development of Graphitization of μg-Sized Samples at Lund University

Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 1270-1276 ◽  
Author(s):  
J Genberg ◽  
K Stenström ◽  
M Elfman ◽  
M Olsson
Keyword(s):  
Mass Spectrometry ◽  
Detection Limit ◽  
Accelerator Mass Spectrometry ◽  
Atmospheric Aerosol ◽  
Pressure Transducer ◽  
Small Sample ◽  
Small Samples ◽  
Mass Detection ◽  
Small Pressure ◽  
Small Sample Sizes

To be able to successfully measure radiocarbon with accelerator mass spectrometry (AMS) in atmospheric aerosol samples, graphitization of small sample sizes (<50 μg carbon) must provide reproducible results. At Lund University, a graphitization line optimized for small samples has been constructed. Attention has been given to minimize the reduction reactor volume and each reactor is equipped with a very small pressure transducer that enables constant monitoring of the reaction. Samples as small as 25 μg of carbon have been successfully analyzed, and the mass detection limit of the system has probably not been reached.

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