A primary objective of this study will be to identify and quantify metabolites of selected dinitroaniline herbicides from rats in both in vivo and liver microsomal in vitro metabolism studied. Particular attention will be directed toward identification of polar metabolites by chromatographic and spectral methods. To this end, it will be necessary to synthesize prospective metabolites of dinitroaniline herbicides, particularly the polar derivatives such as benzimidazoles and their N-oxides, dihydroxy-benzimidazolines, etc., for use as reference standards. In many instances the polar products from metabolic studies have been ignored or regarded as innocuous. However, some benzimidazole compounds are recognized as being mutagenic as are a number of diamino aromatic hair dye components which are structurally similar to known metabolites of dinitroaniline herbicides. Therefore, the mutagenicity of synthetic dinitroaniline derivatives will be evaluated in the Ames Salmonella/mammalian-microsome mutagenicity assay. Four tester strains, TA 1535, TA 1537, TA 100, and TA 98 will be used with and without activation by "S-9" liver homogenate fraction. Appropriate positive and negative controls will be utilized. An attempt will be made to correlate the in vitro metabolism of a dinitroaniline herbicide or a metabolite with microbial mutagenesis using parallel incubations. The incubation conditions will vary using different inducers of liver microsomal enzymes, anaerobic vs aerobic conditions, and varying substrate and enzyme concentrations.