Speciation of Environmental Pollutants by Gc-Aa and by Esca. Purification of Water at Ultratrace Levels of Heavy Metals and Complexation Studies by Electrochemical Methods.

Speciation of environmental pollutants is essential for potential toxicity evaluations. It is important to determine what is the original chemical form of the pollutant when released in the environment as well as all possible reaction products and their potential hazards. The media through which these pollutants are transported in the environment are also of importance. Heavy metal pollutants usually occur in very low concentrations in the environment, therefore, very sensitive techniques are required for the determination of these metals. A GC-AA method was developed that allowed the simultaneous determination of PbEt(,4) and of PbEt(,3)Cl in gaseous and liquid samples. This method enabled the study of the behavior of PbEt(,4) (TEL) and the formation of PbEt(,3)Cl in sea water under several experimental conditions. From the results obtained, the potential hazard of TEL spills at sea was evaluated as well as the effect of particulate materials present in sea water on TEL concentration levels. Airborne heavy metal pollutants were studied by ESCA and the final chemical form of airborne Pb was found to be PbO(,2). Pt was sometimes detected but the determination of its chemical form was not possible. The importance of ESCA as a valuable tool for speciation of airborne matter was demonstrated. Since water free of heavy metal contaminants is essential for the preparation of standard solutions to be used for most environmental and trace metal determinations, an electrochemical method was developed to produce a readily available and economic source of ultrapure water. Because this system was not capable of removing complexed metals from water, a method was developed for the determination of stability constants of heavy metal complexes and for the study of reaction kinetics of complex formation. The electrochemical technique was illustrated with Cd, Pb, and Zn complexes of EDTA. Problems in storing very pure water and very dilute solutions of metal compounds were also discussed. An essentially complete literature review of each subject discussed was included in this dissertation