Increasingly stringent requirements are being placed on the detection and accurate characterization of toxic elements in environmental health. The toxicology of nickel, in elemental and metallo-organic form, has been the subject of much attention in recent years. Nickel has been implicated in numerous carcinogenetic, mutagenetic, metabolic and epidemiological studies. As the knowledge of biological mechanisms expands, the desire to characterize the role of nickel and other metals at incipient and microscopic levels increases accordingly. Recent developments in resonance ionization spectroscopy portend a quantum leap in sensitivity for trace metals. The selectivity and sensitivity of resonance ionization suggest that absolute sensitivities of a few thousand atoms may be achieved for nickel, with attendant benefits of reduced sample preparation, isotope dilution reliability and multielement potential. The specific aims are to: investigate resonance ionization schemes for nickel; develop simplified separation methods for nickel in biological matrices: investigate atomization methods for nickel; and demonstrate ultrasensitive nickel analyses. In Phase II the methodology base would be extended to other toxic elements and a collaborative research program established to integrate the technology into the scientific community. Commercial potential of the technology is expected for analytical services in regional laboratories, and in the dissemination of instrumentation.