T01_P02

The progress of AMS ¹⁴C analysis for small samples down to ultra-microscale size (μg level) at Xi’an AMS Center

Du H^1,2,  Fu Y^1,2, Yang B³, Zhou W^1,2

¹ State Key Laboratory of Loess and Quaternary Geology，Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China, ² Shaanxi Key Laboratory of Accelerator Mass Spectrometry Technology and Application, Xi’an AMS Center，, Xi'an, China, ³Australian Nuclear Science and Technology Organisation, Sydney,  Australia

As the urgent requirement at Xi’an AMS Center for Chronological Research and Tracer applications to radiocarbon (¹⁴C) analyze samples smaller than 0.1 mg carbon (mgC), a compact microgram carbon sample graphitization system has been  applied. The system include two small-volume graphitization reaction units connected quartz manifold and a stainless steel cold finger which can be used as a transfer line for measuring carbon mass and effective trapping of water vapour during the reaction. In a 1.2 mL graphitization reactors we can prepare samples containing 10–600μgC using an iron catalyst with an excess of hydrogen,and even a few micrograms graphite(<10μg) can be obtained. We detailed the effect of the chemical reaction rates with different brand iron catalysts and the morphology analysis of microscale graphite,compared the conventional closed-tube combustion method with the combustion and purification system based on an elemental analyzer (EA) connected to cryogenic traps, especially for the preparation performance of microscale sample. Futhermore, we made some case studies of chronological research on several foraminiferal samples from marine sediment core，and got a series of microgram graphites which have been performed well by our upgrade 3MV Xi’an AMS facility.This is mainly a report of our current capability with the preparation and measurement of micro-sample ¹⁴C-AMS and in the future we will expand the application of microgram carbon sample ¹⁴C-AMS analysis to archaeological bone samples, the microgram carbon graphitisation system will provide the technological opportunities to develop some challenging research.