A review of preconcentration and analytical techniques for metal analysis, with particular relevance to water analysis, is provided in Chapter 1. Supercritical fluid technology and its many applications is also described. In chapter 2, the modification of a porous graphitic carbon material with humic acid, for the preparation of a metal ion chelating solid phase is described. Characterisation of the humic acid material was carried out using UV and IR spectroscopy. The ability of this humic acid modified PGC phase to extract metals from solution is illustrated, with emphasis on Pb2+, Au3+, and Ni2+. This modified PGC material was applied to off-line preconcentration of lead in drinking water samples prior to determination by GFAAS. Chapter 3 describes the rapid, selective extraction of precious metals, Au3+, Pd2+ and Ag+ on a novel sc-CO2 fluorinated thiourea ligand impregnated Si-PTFE membrane. Optimization of the impregnation process was studied in terms of temperature, pressure and diffusion time in the supercritical fluid reaction vessel. SEM and DRIFT analysis of the Si-PTFE membrane before and after impregnation confirmed that the desired immobilization was achieved without physically damaging the membrane surface. The performance of the SPE membrane was compared with sc-CO2 fluorinated thiourea ligand impregnated silica particles as a SPE cartridge. The use of the modified Si-PTFE membrane to quantify trace Ag+ in an environmental sample was demonstrated. In chapter 4, a selective supercritical fluid (sc-CO2) extraction method for precious metals, from spiked cellulose paper, a ceramic surface and a reference ore material is investigated using a fluorinated thiourea ligand. While flame atomic absorption spectroscopy is used to monitor the efficiency of extraction, a preliminary investigation of colorimetric detection using Thionine is also examined. Finally in chapter 5, the ion chromatography of lead and copper ions, on a porous graphitic carbon column using an acidic and oxalic acid mobile phases is described. On-line preconcentration of metal ions using a calix[4]arene tetrahydroxamate precolumn in comparison to direct injection of large volumes is investigated for analysis of Pb2+ and Cu2+ in environmental water samples.