*** 9634259 Klinkowstein This Small Business Innovation Research Phase II project is to develop a compact, low cost accelerator mass spectrometry (AMS) system for the measurement of ultra-low quantities of carbon-14 and tritium in labeled biological samples. The instrument will have a sensitivity 100-1000 times higher than that of liquid scintillation decay counters and will allow the measurement of carbon-14 concentrations at or below naturally occurring levels in contemporary samples. The high sensitivity afforded by AMS allows the fate of environmental carcinogens, mutagens, and toxins to be studied on the molecular level at extremely low levels of exposure. Existing AMS systems use large, costly nuclear physics accelerators which are not generally available to biomedical researcher and are not compatible with interface to standard chromatographs used for the purification of biological samples. The research is intended to lead to development of a dedicated, biomedical AMS system based on a new approach which allows the accelerator energy to be lowered by approximately a factor-of-three compared with existing systems. This greatly reduces the size, cost, and complexity of the instrument. The feasibility of this approach was demonstrated in the Phase I experiments which showed that an AMS system using a 1 MV tandem accelerator will allow the unambiguous detection of 14C in labeled contemporary samples. The Phase II research will focus on the construction and testing of the first on-line sample purification and injection interface for biomedical AMS. The interface will make possible the direct introduction of biological samples from a gas chromatograph into an AMS system thereby allowing the use of AMS in conjunction with standard, high resolution chemical separation techniques. The system will provide the critical front-end technology for a dedicated low energy AMS instrument and will also make possible the use of any existing AMS system for on-line analysis of biological samples. This system will be of interest to research and analytical laboratories studying the biological effects of environmental carcinogens and genotoxins. ***
