Physical Sciences and Mathematics Commons^™

Effects Of Humic Acids And Salinity On Pesticide Bioavailability And Toxicity As Estimated By Spme And Toxicity Tests, Laurent C. Mézin

Dissertations, Theses, and Masters Projects

The interactive effects of humic acids (HAs) and salinity on the bioavailability and toxicity of the pesticides chlorpyrifos and 4,4'-dichlorodiphenyltrichloroethane (DDT) were investigated. The effects of various HAs on the toxicity of chlorpyrifos were initially assessed with the chronic MicrotoxRTM test. Environmentally relevant concentrations of Aldrich, Peat, Leonardite and Suwannee River HAs had no significant effect on the toxicity of either chlorpyrifos or copper (Cu), the test's positive control. as reductions in contaminant toxicity had previously been reported for some contaminants by HAs, it appeared that salinity might be a mitigating factor. Thus salinity effects were further investigated with Aldrich …

Development Of Amperometric Enzyme Electrodes For Glucose And Hypoxanthine., Eilish Broderick

Theses

This thesis is concerned with the immobilisation of enzymes on electrosynthesised poly (o- phenylenediamine) membranes for use on amperometric electrodes. The thesis opens with a discussion of the basic principles of enzymology and a review of a diverse range of biosensors, followed by a consideration of amperometry as governed by the Cottrell equation.

Glucose oxidase and horseradish peroxidase were co-immobilised in poly (o-phenylenediamine) on platinum electrodes at + 0.6 V versus Ag/AgCl. Using this approach the enzymes are entrapped in a strongly adherent, highly reproducible thin membrane, of thickness approximately 10 nm. This one-step procedure produces a glucose sensor with …