The goals of this project include: (1) the development of methodology for the quantitative analysis of mercury in various biological products (for example, influenza virus vaccine and immune serum globulin) resulting from the use of mercurial preservatives, (2) develop methodology for the quantitative analysis of thimerosal molecule and any of its degradation products, (3) determine stability of mercury and thimerosal in various products, and (4) determine different mercury species present in various products containing thimerosal such as Immune Serum Globulin, DTP Vaccine, etc. Cold vapor atomic absorption spectrophotometric methodology has been developed to determine the total mercury. Liquid chromatography combined with inductively coupled argon plasma emission spectrometry/mass spectrometry (LC-ICP/MS) has been used to quantitative thimerosal in diluent, a Tetanus Toxoid Adsorbed and Influenza Virus Vaccine. Trace analysis work is being done with phosphorus in conjugate vaccines using ICP. Fluorescent techniques will be applied to the determination of thimerosal's degradation products.