The 1-MV spectrometer at the Center for Accelerator Mass Spectrometry, located at Lawrence Livermore National Laboratory, is dedicated to quantitating 14C and, recently, 3H within biochemical samples. Over 30,000 samples have been analyzed since operations began in May, 2001. High measurement throughput is enabled by the use of the LLNL high-output Cs-sputter solid sample ion source. The use of solid targets necessitates the off-line conversion of materials to graphite or TiH2. Ion sources that are compatible with the direct input of biochemical separation instrumentation such as liquid chromatography, capillary electrophoresis or other instruments would allow for real-time, automated sample preparation, potentially leading to increased resolution, minimal handling and the ability to do molecule-specific tracing of very small samples, but with a cost in precision. Such an approach involves the direct introduction of carbon, as CO2, or hydrogen, as H2, into the ion source. We have purchased a gas-accepting ion source from National Electrostatics Corporation (Middleton, WI) and plan to install it onto our 1-MV AMS spectrometer to use in addition to our current ion source. We have performed ion–optics calculations and designed a beam line to transport both carbon and hydrogen isotopes, while matching the phase space of the ion beam to the acceptance of the accelerator. Presently, this source and beam line are under construction on a test bench where we will evaluate performance. If necessary, we will modify the ion source to maximize output in the ionization and ion beam transport of both gaseous and solid targets. Once installed onto our existing spectrometer, we plan to link a nanoflow LC system to this ion source through an online combustion furnace to provide directly coupled AMS quantitation of 14C and 3H from biochemically separated compounds. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48 and under the National Center for Research Resources Grant # RR13461.
See more of Poster Session I
See more of The 10th International Conference on Accelerator Mass Spectrometry (September 5-10, 2005)