The proposed research is directed towards the further development of precise, accurate and sensitive electroanalytical methods for volatile and non-volatile N-nitrosamines and the nitrosamine precursors nitrate and nitrite. The methods must be capable of analyzing a wide variety of complex matrices including various body fluids. They must also be useful for in situ studies and be applicable to the analysis of small samples. The analytical methods will be applied to problems of significant chemical and biological interest such as studies designed to investigate the role of ascorbic acid and alpha-tocopherol in the formation and possible destruction of N-nitrosamines. Rates of metabolism and the effect of metabolic inhibitors will be studied using single animal techniques plus the electroanalytical methods. A simple sensitive method for total nitrosamine analysis will be developed that is capable of treating small samples. The method will be used to study various possible routes of endogenous formation of N-nitrosamine, including comparison of nitrosamine content of portal blood with that of ciruclating blood. The new electrochemical detector for high performance liquid chromatography (HPLC) will be evaluated and compared with the thermal energy analyzer detector.