| Previous work by our research group demonstrated that quantitative chemical analysis of analytes, such as mercury and chromium species, in environmental matrices could be successfully carried out without using calibration curves and with correction for species interconversion by using EPA Method 6800A. This method encompasses isotope dilution mass spectrometry (IDMS) and speciated isotope dilution mass spectrometry (SIDMS), both of which are described in detail in chapter 1. Research described in this dissertation expands upon our earlier work by applying the method to the speciation of mercury in biological matrices, the speciation of glutathione in red blood cells and whole blood, and the analysis of enzyme activity in mammalian tissue.;For example, in an experiment involving mercury speciation in a hair sample (chapter 2), EPA Method 6800A corrected for the conversion of over 70% of the C2H5Hg+ to Hg2+, as well as other conversions that occurred, so that the correct concentrations of all mercury species present could be obtained.;EPA Method 6800A was also used for the analysis of glutathione in red blood cells in two autism studies (chapter 3). In one of the studies, analysis of 16 matched pairs of control and autistic samples demonstrated that red blood cell total glutathione concentrations were higher in samples from autistic patients than ones from controls (p=0.012), suggesting that the autistic patients studied may be making more glutathione in response to a larger toxic burden of heavy metals such as lead, antimony, aluminum, and cadmium, compared to controls.;Another application of EPA Method 6800A involved the analysis of alpha -- Galactosidase A (GLA) activity in liver, kidney, and brain tissues harvested from mice as part of the development of a gene therapy animal model for Fabry's disease (chapter 4). In this study, EPA Method 6800A successfully distinguished between samples from gene deficient and wild type mice, as well as mice exposed to two different dosages for gene therapy treatment.;The successful application of EPA Method 6800A in biological matrices described in this dissertation should serve to foster further usage of it in fields such as medicine, toxicology, and agriculture. |
