The first part of this work was concerned with the use of a ternary complex, formed by the sensitisation of the aluminium catechol violet complex with cetyltrimethylammonium bromide, for the determination of aluminium. A solvent extraction system was developed using benzoic acid in ethyl acetate to extract the aluminium away from a number of interfering species, principally iron and some divalent cations. The aluminium was then back-extracted into aqueous solution for subsequent determination. EDTA was used as a mass masking agent for small quantities of interfering cations. A number of other ternary complexes of the first-row transition elements with catechol violet and cetyltrimethylammonium bromide were prepared for the first time. The extinction coefficients were measured and a preliminary investigation of the compositions was undertaken. It is suggested that the iron catechol violet cetyltrimethylammonium bromide complex is suitable for further development as a spectro-photometric reagent. The middle section of this work was concerned with the development of a sensitive flame speotrophotometrie method for boron, using the emission from the BO₂ radical in an oxygen-hydrogen-nitrogen co-axial flame, The technique was found to depend for its sensitivity upon the anomalously high volatility of boric acid in absolute methanol to achieve an indirect nebuliser efficiency approaching 60%. The latter part of the work was concerned with the calculation of free atom concentrations of elements in a number of flames. The atomisation of boron in five analytical flames was studied using this method using a digital computer to generate graphs of the dependence of atomisation upon flame stoichiometry. This computer technique was also used to study the anomalously low sensitivity of determination of zirconium in the nitrous oxide acetylene flame. Data for titanium were also generated as a comparison. The study showed that condensed zirconium carbide is formed in the fuel-rich flame, seriously reducing atomisation. In fuel-lean flames zirconium oxide species occur to lower the atomisation