| Summary: | This thesis describes studies made into flow injection analysis or unsegmented continuous flow analysis, a recently developed automatic method of analysis of solutions. The state of the art of flow injection analysis is presented in the form of a review. The aim of the experimental work was to develop apparatus and methods for trace multielement determinations particularly of metal ions. A novel and versatile miniature flow through phototransducer was developed with all solid state light components. The inherent stability of these components gives rise to very high sensitivity in colorimetric analysis. A particular orientation of the light components yields a transducer highly sensitive to refractive index allowing accurate refractometric determinations to be performed. The principle of operation of this refractometer has been determined and is described. The transducer was used as a colorimeter in two chemical systems to perform multielement determinations on a single sample plug. In the first, the reproducible concentration gradients of the sample-carrier interfaces are an integral part of the method. The pH-gradient flow injection analysis method uses a pH-gradient created by the injection of strong base into a system of weak acid(s) (or strong acid into a system of weak base(s)). pH changes occur across the sample such that selective conditions for the analysis of individual analytes are attained at different points along the pH gradient. The viability of the method is demonstrated with lead(II) and vanadium(V), cobalt(II) and manganese(II), copper(II) and nickel(II), and copper(II) and manganese(II). The second method utilises the reproducible timing between injection and analysis in a two point kinetic assay of cobalt(II) and nickel(II) using the differential reaction rates of the pseudo-first-order dissociation of the citrate complexes and a subsequent scavenging reaction. On stream masking of interfering ions with EDTA yields a highly selective analysis.
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