This thesis is a study of the application of modern electroanalytical techniques to the determination of analytes in complex media. The recent large increase in publications applying electroanalytical techniques to environmental, pharmaceutical and clinical applications is discussed in Chapter 1, including a discussion of electrode materials and their applications, the use of modified electrodes to improve selectivity and reduce electrode passivation, in addition to an overview of the use of electrochemical detection in flowing solution analysis. Chapter 2 describes the use of polarography at a dropping mercury electrode to investigate the cure chemistry o f anaerobic adhesives. The influence of transition metal ions, in the presence of accelerators, on the catalytic decomposition of the free radical initiators /-Butyl perbenzoate, /-Butyl hydroperoxide and benzoyl peroxide is discussed. The determination of clenbuterol in bovine urine is discussed in Chapter 3. The electrochemical characteristics of the |3-agonist were investigated at a bare carbon paste electrode. The application of a thin Nafion film to the electrode surface permitted accumulation o f clenbuterol onto the electrode surface while at the same time selectively excluding anionic interferences present in the urine sample. Differential pulse voltammetry was used to detect low levels of clenbuterol in urine. Amperometric and voltammetric detection coupled to capillary electrophoresis, applied to the determination of anionic phenolic acids in beer and wine, is outlined in Chapter 4. The passivation of the carbon fibre working electrode by the large concentration of neutral molecules present in the sample was overcome by injecting a large volume of diluted sample into the capillary, reversing the polarity to remove cations and neutral molecules from the capillary, and separating the remaining anions under normal conditions. Hydrodynamic voltammetry obtained amperometrically by the step-wise increase in potential were compared to voltammetric detection in the production of i-E curves for analyte identification. Conclusions drawn from the work carried out in the thesis and suggestions for future research are outlined in Chapter 5.