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On-line Radiocarbon Measurements of Small Samples Using Elemental Analyzer and MICADAS Gas Ion Source

Published online by Cambridge University Press:  18 July 2016

M Ruff ,
S Fahrni ,
H W Gäggeler ,
I Hajdas ,
M Suter ,
H-A Synal ,
S Szidat  and
L Wacker
M Ruff*
Affiliation:
Laboratory for Radio- and Environmental Chemistry, University of Bern, Switzerland. Paul Scherrer Institute, Villigen, Switzerland. Laboratory for Ion Beam Physics, ETH Zurich, Switzerland.
S Fahrni
Affiliation:
Laboratory for Radio- and Environmental Chemistry, University of Bern, Switzerland. Paul Scherrer Institute, Villigen, Switzerland.
H W Gäggeler
Affiliation:
Laboratory for Radio- and Environmental Chemistry, University of Bern, Switzerland. Paul Scherrer Institute, Villigen, Switzerland.
I Hajdas
Affiliation:
Laboratory for Ion Beam Physics, ETH Zurich, Switzerland.
M Suter
Affiliation:
Laboratory for Ion Beam Physics, ETH Zurich, Switzerland.
H-A Synal
Affiliation:
Laboratory for Ion Beam Physics, ETH Zurich, Switzerland.
S Szidat
Affiliation:
Laboratory for Radio- and Environmental Chemistry, University of Bern, Switzerland. Paul Scherrer Institute, Villigen, Switzerland.
L Wacker
Affiliation:
Laboratory for Ion Beam Physics, ETH Zurich, Switzerland.
*
Corresponding author. Email: matthias.ruff@eawag.ch.
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Abstract

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An on-line measurement system was installed at the MICADAS in Zurich, using an elemental analyzer (EA) as a combustion unit to enable direct radiocarbon measurement of samples containing carbon in the range of 5–100 μg possible with minimum effort. The samples are combusted in small capsules and the gaseous combustion products are separated by the EA. The carbon dioxide leaving the EA in a high helium flow is concentrated on a small external trap containing X13 zeolite adsorber material. This new concept, avoiding a cryogenic trapping for the enrichment step, allows the construction of a very compact system able to work even with the smallest samples. Concentrated on the external trap, the carbon dioxide is flushed into the gas-tight syringe of our gas inlet system using a low helium stream. The gas mixture is measured with the MICADAS gas ion source. Several different sample capsules were analyzed to minimize the major blank contribution coming from the sample vessel. The best results were achieved with 25-μL tin capsules, which contained only 0.34 ± 0.13 μg carbon at 65 pMC. This work describes the development of the on-line system and the protocol for measurement runs. Results are presented for on-line measurements of reference materials and a comparison is performed with typical dating samples measured previously as graphite targets. Finally, relevance and limitations of on-line measurements are discussed.

Type
Methods and Developments
Information
Radiocarbon , Volume 52 , Issue 4 , 2010 , pp. 1645 - 1656
Copyright
Copyright © The American Journal of Science 

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