New Approaches to Electroanalysis of Metals and Pretreatment of Biological and Environmental Samples

Biological and environmental sample pretreatment followed by electrochemical sensing are the focus of this dissertation. The Advanced Oxidation Process (AOP) treatment using aqueous hydrogen peroxide and UV irradiation with acid deactivation of the enzyme catalase in blood has been developed and optimized. The kinetics of whole blood AOP in a single-cell reactor was studied, and the effect of pH on the AOP process has been investigated. A new method of dry ashing whole blood has been developed and optimized for trace metal analyses. The new method and subsequent metal analyses in the blood samples has been used to confirm results from both AOP pretreatment and analyses using electrochemical sensors. Chromium(VI) detection is the focus of the electroanalysis with two new electrode systems described. The fabrication of a flower-like self-assembly of gold nanoparticles (AuNPs) on a glassy carbon electrode (GCE) displays an unusually large, linear concentration range in the parts per trillion to low parts per billion range. Another novel electrode is fabricated using a modified glassy carbon electrode with physical deposition of single-walled carbon nanotubes followed by electrochemical deposition of a sol-gel using base-catalyzed hydrolysis with detection of Cr in the low ppb and ppt range.