Liquid Scintillation 14C Spectrometry: Errors and Assurances

Abstract

Liquid scintillation (LS) 14C spectrometry, using ultra low-level, high-efficiency and resolution alpha and Beta particle detection equipment is seen as an excellent tool supporting future 14C radiometry. Modern technology ensures electronic excellence: high-precision, smallsample (100mg) dating ability, flexibility of use for the detection of alpha and Beta particle emitting radioisotopes at and below natural abundance levels. Multiple applications to environmental research, supported by elegant software and commercial availability, are its attributes. However, mastering the new technology takes time as lessons learned in gas-proportional 14C radiometry and high-background counting are not directly applicable to ultra low-level 14C LS spectrometry using benzene as the counting medium. That discordant results can be obtained by any technique based on physical measurement is well established. This is demonstrated for 14C age determination by reference to an international cross-check organized by the University of Glasgow. Reasons for aberrations are explored and the question is raised if it is not timely to introduce the type of quality assurance practiced by other analytical disciplines. Better results will not only serve the daters and users but will generally enhance the value of worldwide 14C research.