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Illinois State Geological Survey Radiocarbon Dates I

Published online by Cambridge University Press:  18 July 2016

Stephen M. Kim  and
R. R. Ruch
Stephen M. Kim
Affiliation:
Illinois State Geological Survey, Urbana, Illinois 61801
R. R. Ruch
Affiliation:
Illinois State Geological Survey, Urbana, Illinois 61801
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The radiocarbon dating laboratory of the Illinois State Geological Survey has been established to satisfy a growing need for radiocarbon dates for an active Pleistocene research program. Because of the age and type of material dated, the benzene liquid scintillation counting method is employed in this laboratory. The detailed chemical procedure for converting carbon to benzene has been published by Noakes, Kim, and Stipp (1965) and Noakes, Kim, and Akers (1967); however, the procedures for benzene synthesis and sample counting are briefly explained below to clarify this laboratory's procedure.

An organic sample, such as peat, organic silt, or wood, is burned and the CO2 evolved is absorbed in NH4OH. SrCl2 solution is added to precipitate the carbonate, and the solution plus precipitate is boiled and cooled before filtration of SrCO3. The SrCO3 is acidified with dilute H3PO4 to liberate CO2 in a closed system, and the CO2 is converted to C2H2, as reported by Barker (1953). In this method, 2.4 gm of dry packed lithium, obtainable from the Lithium Corporation of America, is used for each liter of CO2 that is converted to C2H2. Trimerization of the C2H2 to form C6H6 is accomplished using a vanadium-alumina catalyst.

To the C6H6 synthesized from the sample carbon, 2 cc of toluene containing 100 mg Butyl-PBD, 2-(4-tert-Butylphenyl)-5-(4-Biphenylyl)-1,3,4-Oxadiazole, are added, and this mixture is made to a total volume of 10 cc with spectrograde C6H6. A modified Packard Instrument Co. liquid scintillation spectrometer (Model 3375) is used for measurement of C14 activity.

Ages are calculated from a C14 half-life of 5568 years, and the standard deviation (1σ) is based only on counting errors; however, if calculated error is less than 200 years, 200 years is chosen as one standard deviation (1σ).

Type
Research Article
Information
Radiocarbon , Volume 11 , Issue 2 , 1969 , pp. 394 - 395
Copyright
Copyright © The American Journal of Science 

References

Date lists: Google Scholar
ANU I Polach, , Stipp, , Golson, , and Lovering, , 1967 Google Scholar
FSU I Stipp, , Knauer, , and Goodell, , 1966 Google Scholar
ORINS I Noakes, , Kim, , and Akers, , 1967 Google Scholar
Barker, H., 1953, Radiocarbon dating; large scale preparation of acetylene from organic material: Nature, v. 172, p. 631–632.CrossRefGoogle Scholar
Noakes, J. E., Kim, S. M., and Akers, L. K., 1967, Recent improvements in benzene chemistry for radiocarbon dating: Geochim. et Cosmochim. Acta, v. 31, p. 1094–1096.CrossRefGoogle Scholar
Noakes, J. E., Kim, S. M., and Akers, L. K. 1967, Oak Ridge Institute of Nuclear Studies radiocarbon dates I: Radiocarbon, v. 9, p. 309–315.CrossRefGoogle Scholar
Noakes, J. E., Kim, S. M., and Stipp, J. J., 1965, Chemical and counting advances in liquid scintillation radiocarbon dating: Sixth Internatl. Conf. Radiocarbon and Tritium Dating Proc., Conf-650652, p. 68–98.Google Scholar