Pulsed electrochemical detection of organic sulfur compounds following separation by microbore high performance liquid chromatography or capillary electrophoresis.

摘要

The use of Pulsed Electrochemical Detection (PED) following separation by micro separations methods was explored for organic sulfur compounds lacking strong chromophores or fluorophores. Techniques employed were microbore reversed-phase HPLC, capillary reversed-phase HPLC, and capillary electrophoresis.;Preliminary electrochemical characterization of selected sulfur compounds showed similar behavior of all compounds, consistent with the theory of AuOH-catalyzed oxidation of adsorbed analyte. Electrochemical characterization studies were the basis of optimization studies for the PED technique of Pulsed Amperometric Detection (PAD). Limits of detection for microbore HPLC, using a 1mm diameter disc microelectrode and optimized PAD waveform, were 0.5 to 2 picomoles for compounds cysteine, glutathione, dithierythritol, trans-1,2-dithiane-4,5-diol, and cystamine. Another technique, Integrated Pulsed Amperometric Detection (IPAD), was found to give less baseline drift and lower limits of detection than PAD: 0.25 to 1 picomoles. Corresponding limits of detection for capillary liquid chromatography of 0.1 to 0.2 pmol were obtained with an IPAD waveform and 1mm Au electrode. A gold fiber electrode, 12 microns in diameter gave lower limits of detection, 20 femtomole for trans-1,2-dithiane-4,5-diol, due to faster response. Pulsed electrochemical detection techniques were also used in the analysis of samples of foodstuffs containing organic sulfur compounds.;Pulsed electrochemical detection techniques were extended to capillary electrophoresis. The fast response of gold fiber electrodes, 12