Development and Applications of Gas Chromatography - Atomic Absorption Interface Instrumentation.

It is being recognized that we are exposed to increasing numbers of poorly understood and potentially toxic substances within our environment. To understand fully the human health effects and environmental impact of these hazards, complete chemical characterization or speciation studies of these hazards is necessary. Once exposure to a toxic substance has occurred, the physical and chemical form will determine the length of time a compound will remain in the environment and the types of chemical reactions that will occur in atmospheric, aquatic, and soil environments. Physiological and toxicological effects are also dependent upon the chemical form and physical form. This dissertation has been limited to heavy metal chemical hazards, and more specifically to lead and cadmium and their compounds. A new atomic absorption (A.A.) detector for gas chromatography (G.C.) was developed. It was directly interfaced to a gas chromatograph through a pyrex transfer line. The detector exhibited the excellent specificity of atomic absorption while retaining the sensitivity of carbon furnace atomizers. The G.C.-A.A. system permitted detection of different chemical forms of a given element. The determination of lead alkyls in gasoline was chosen as a practical sample to demonstrate the G.C.-A.A. as an important analytical technique for characterizing mixtures containing volatile metal compounds. Unleaded gasolines were also analyzed for lead compounds. It was discovered that the G.C.-A.A., could be utilized as a nonspecific detector for organic compounds with various functional groups. A new modified G.C.-A.A. detector was designed and built. The purpose of the design was to improve the lifetime of the resistance heated carbon element. The evaporation of lead alkyls from gasoline was studied to determine the possible contribution of evaporating gasoline to atmospheric lead concentrations. The reactions of tetraethyl lead in sea water were also studied. The reaction of cadmium and Vitamin methyl B(,12) was studied. A volatile cadmium compound was formed but the quantity formed was insufficient to characterize it completely. The G.C.-A.A. system developed in this research is very sensitive and selective. It is ideal for speciation studies involving volatile metal compounds and complexes