As the use of marihuana has continued to grow, the need for accurate and reliable means of measuring cannabinoid levels has become more urgent. This proposal addresses the development of new chemical assays for the cannabinoids. The Phase I application outlines our interest in developing such an assay, which will be rapid, non-isotopic and capable of being performed in a 'field' setting. Our 2 specific Phase I goals will be 1. generate murine monoclonal antibodies to THC and 2. commence development of a sensitive and versatile THC fluorescence immunoassay which will be faster, easier and at least as sensitive as current radioimmunoassays (detects 10ng/ml THC). Purified monoclonal antibodies will be conjugated to B-galactosidase and used in a heterogeneous competitive assay format. We intend to pursue solid-phase technology for immobilization of THC-BSA conjugates, which will then compete with test sample for binding to antibody-enzyme conjugates. Enzyme activity (and subsequently, THC concentrations) will be measured in a fluorescence assay, monitoring the formation of methyl-umbelliferone from the non-fluorescent substrate, methyl-umbelliferyl galactoside. The final (fluorescence) measurements can be made in any appropriately set fluorimeter, or in a low-cost, portable photon-counting fluorimeter which we have been developing for use with such immunoassays. Both the instrument and the assay format are geared towards rapid, technically facile performance in a laboratory or 'field' setting. We are aware of the need for such assays by law enforcement agencies, civilian groups, and the military and we believe that as sensitive, reliable and simple THC (cannabinoid) detection system wil have a significant commercial market. Our group is also well positioned to attract follow-on funding for this project, and develop/market such a commercial product(s). We feel that the methodologies developed will be generally applicable and should eventually lead to convenient and sensitive assays for other drugs of abuse.