Determination of uranium in the urine of workers is required by the NRC at nuclear facilities. Extremely low concentrations of uranium, especially in small samples, are difficult to measure using existing technology. Future NRC plans to characterize bioavailable uranium fractions comprising the uranium body burden will require even higher sensitivities. High sensitivity technology developed for uranium is potentially amenable to numerous bioassay, environmental, geological, and semiconductor materials applications. Recent developments in autoionization-mediated laser photoionization (A-MLAP) mass spectrometry suggest that new levels of sensitivity and selectivity may be attainable to meet evolving needs for iranium (bio)assay. The purpose of this project is to explore the feasibility of A-MLAP for uranium analysis. We propose to evaluate autoionization pathways, atomization efficiency, a pilot uranium in urine quantification study and extrapolation of the methodology to continuous wave solid- state laser systems. A successful completion of this project would permit implementation of the technology in a high sensitivity analysis system in phase ii and beyond. Res: