GAMMA-METRICS and Oak Ridge National Laboratory have developed a prototype portable toxic chemical analyzer (TCA) for environmental screening using surface enhanced Raman scattering technology. The focus is on detection of anthropogenic chemicals such as polycyclic aromatic compounds. In this instrument, a laser illuminates a small sample of analyte on a substrate of silver coated particles. Light scattered from the illuminated spot is analyzed to determine the chemicals in the analyte. The development process involved miniaturizing the instrument from a large laboratory table-top device to a small portable package, then ruggedizing the components and the packaging to withstand field conditions. A reference design for a commercial instrument has been developed. The instrument employs internal direct optics or, optionally, an external, in-situ probe connected by fiber optics to