David Price


This thesis describes the design, assembly and optimisation of a flow injection-chemiluminescence (FI-CL) procedure for the determination of hydrogen peroxide (H2O2) in seawater. An overview of the biogeochemical importance of H2O2 in seawater is presented in Chapter One. The use of both flow injection and chemiluminescence based methods are also reviewed. Chapter Two describes the type of analytical instrumentation used in both flow injection and chemiluminescence methods. Each component is described and its suitability to the FI-CL method discussed. Two detection systems; photomultiplier tube and photodiode, and two flow cell designs; coiled glass and lamina, were compared for their suitability to the method. A charge coupled device was used to obtain the CL spectra of the luminol CL reaction and automation of the FI manifold is also described. Chapters Three and Four describe the optimisation of the FI-CL method and its suitability to the determination of H2O2 in natural waters (river, estuarine and sea). Matrix efifects are investigated and a standard addition procedure described. The analytical figures of merit for H2O2 determination include a limit of detection of 10 nM and a linear range of 10-500 nM. The application of the fully optimised method to the in situ determination of H2O2 in the western Mediterranean is described in Chapter Five. Hydrogen peroxide depth profiles are presented from different geographical areas and diurnal variations in H2O2 concentration discussed. The final experimental chapter investigates the photochemical generation of H2O2 in both synthetic and natural water matrices. Ambient light incubations at sea and artificial light incubations in the laboratory were made.

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