The thesis comprises two parts. Part one involves the principles and applications of the voltametric techniques, and part two deals with the studies on characteristics of the mercury preplated gold wire microelectrode and its application in determination of lead at level of ppb. In part one, the basic measurement of voltametric methods is described, the diffusion current at different kinds of electrode’s geometries are considered. Moreover, the specific properties and limitations of various kinds of the techniques (cyclic voltametry, anodic, cathodic, potentiometric and absorptive stripping voltametry) associated with different approaches of the potential excitations are discussed (linear sweep, normal pulse, differential pulse and square wave). Subsequently, the applications of voltametric techniques in variety of samples (environmental, biological, foodstuffs, and pharmaceutical samples) for determination of many kinds of pollutants (inorganic, organic, an organometallic substances) are given. The widespread utility of voltametry demonstrates the reliability of the techniques. In part two, preliminary studies of the behaviours of mercury coated gold wire microelectrode are concerned. The electrode exhibits specific characteristics such as high sensitivity, fast scan rate utility, and possibility to be employed in unstirred condition. Analytical parameters for lead are examined. The effects of oxygen, stirring, electrolyte compositions, deposition time and potential, and scan rate are tested. With the optimized conditions, good repeatability is obtained (4% at Pb 70ppb for 30s deposition, 8% at 30 ppb for 60s deposition, and 11% at 10ppb for 60s deposition). The influences of copper, iron and cadmium are investigated. Moreover, a brief discussion on the stability of the electrode as well as its film thickness-dependent performances is also concerned.
|Uddannelser||Kemi, (Bachelor/kandidatuddannelse) Bachelor el. kandidat|
|Udgivelsesdato||1 jan. 2006|
|Vejledere||John Mortensen & Ba Hoai Anh Nguyen|