| Flow injection analysis (FIA) is the modern sample handling technique under heterogeneous and non-equilibrium state. It has been widely accepted in the field of automatic analysis for the advantages of high speed, versatility for on-line treatment and various detection method, high precision, and saving of reagents. The detector is the critical part of any FIA system because it to a large extent decides both selectivity and sensitivity of a particular determination. It has been proved advantageous to combine the FIA with electrochemical detection method. The currently used electrochemical methods are mainly potentiometry, amperometry and biamperometry.Biamperometry, based on principle of so-called dead stop endpoint detection, has been widely used in flow analysis for its simplicity, high sensitivity, high selectivity, and high signal to noise ratio. It has been used for reversible or quasi-reversible couple systems when both the oxidized and reduced forms are present in the flow through cell. However, only few reversible couple systems such as k/F have been used successfully, which prevents the method being more widely used. The biamperometry for irreversible redox couples system has not to date been reported.This dissertation includes the works in the following aspects. 1. Firstly the principle of biamperometry for irreversible redox couple is proposed for flow injection analysis. The method is studied from both theoretical and experimental point of view. The general rules for establishing biamperometric detection system, and the influences of experimental parameters are discussed. 2. By coupling the oxidation of the analytes having mild oxidation potentials with the reduction of platinum oxide or gold oxide to form biamperometric detection schemes, flow injection systems are established for above 10 important compounds related to pharmaceutics, biochemistry, environment, and industry. 3. The method is used for the analytes having high redox potentials. As example, by coupling the oxidation of phenols with the reduction of MnO4-, a new flow injection method for the determination of total phenols in environmental water is proposed. 4. Design and construct a thin-layer biamperometricdetection cell for the analytes having mild oxidation potential and a biamerometric cell for the analytes having high redox potentials.The works in the dissertation enriched the basic electroanalytical method for FIA. With inheritance of the conventional advantages of high selectivity and signal to noise ratio of direct biamperometry, the application scope of the biamperometry in flow injection analysis has been largely extended. The method is instructional in developing high performance electrochemical detectors or sensors for flow systems such as flow injection analysis, liquid chromatography, and capillary electrophoresis.The dissertation consists of three parts.Part I ReviewChapter 1: The achievements on flow injection analysis with electrochemical detection are reviewed particularly with 153 references up to the year of 2000.Part II Principle and fundamentalsChapter 2: Biamperometry for the direct determination of irreversible redox couple in flow system has been proposed based on coupling two independent and irreversible couples. The method is studied both theoretically and experimentally. Equations describing the current-voltage characteristics and the current-concentration relationship are presented. The influence of the applied potential difference (AE) and the half-wave potential difference (AEm) between the two irreversible couples on the method are discussed. It shows that small AEm is favorable to construct biamperometric detection system and to achieve high sensitivity and selectivity. Increasing AE leads to an increase in sensitivity. This is, however, accompanied by a decrease in selectivity and signal to noise ratio. To construct biamperometric detection scheme for irreversible system with large AEm, two approaches, adjusting acidity of supporting electroyte or adding new irreversible...
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