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|Title:||Rapidly Scanning Coulostatic Liquid Chromatography/electrochemistry Combined With Conventional Amperometric Detection in a Series Dual-Electrode Cell|
|Author(s):||Trubey, Richard Keith|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The technique of rapidly scanning coulostatic pulse amperometry is combined with conventional fixed-potential amperometry in a series dual-electrode cell to create a novel detector for high performance liquid chromatography. After a preliminary period of electrode evaluation, a flow cell was designed and constructed to permit compatible operation of a coulostat and a potentiostat as they simultaneously controlled electrode potentials. A circuit for minimizing crosstalk effects was implemented. Existing coulostat software was extensively revised to add the capability to scan in either direction through a range of potentials which included 0.00 V. Reliable achievement of new potentials and precise holding of existing potentials were also greatly improved.
Use of the coulostat downstream of an electrode held at fixed potential was studied initially and quite thoroughly. The capabilities to obtain voltammetric information about both injected species and products of upstream electrode reaction were demonstrated. Hydroquinone at gold yielded a voltammetric detection limit of 10('-4) M. The analytical (chromatographic) detection limit was found to be 1.6 x 10('-5) M. A gold-mercury amalgam electrode was found to possess superior properties. Application to a mixture of sulfur-containing organic compounds was investigated.
The feasibility of coulostatic detection upstream of an electrode under potentiostat control was also studied. Significant voltammetric information was found to exist at the downstream electrode. This information, however, is somewhat convoluted by a transit time (between working electrodes) that is slow relative to the duration of a scan. The need for further investigation of this detection strategy is indicated.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986.
|Date Available in IDEALS:||2014-12-15|