The key issue for radiocarbon dating to extend its applicability to older ages is to reduce its background level in particular for the laboratory that employs Liquid Scintillation method (LSC). LSC is still widely used in the radiocarbon measurements since the system can be relatively easily handle. There are mainly two types of secondary carbon contaminations namely that occurred before and after sample preparation in a laboratory. Former can be minimized using thorough cleaning method such as AAA and this is equally important for both LSC as well as Accelerator Mass Spectrometric method (AMS). However the latter is more significant for LSC laboratory since the method requires larger amount of samples, chemical regents, and more preparation steps. We conducted AMS measurements using intermediate product after the each pretreatment steps of LSC to find the degree of secondary carbon input during the laboratory experiments. As the result, the memory effect in benzene chemical compounding system of LS spectrometry was found as the most significant contributor of secondary carbon to the final product. It is possible to reduce the background of the pretreatment system using the protocol employed in this study, when the facility of the LSC is installed.
See more of Poster Session II
See more of The 10th International Conference on Accelerator Mass Spectrometry (September 5-10, 2005)