Selective Determination of Cytochrome c by Capillary Zone Electrophoresis with Amperometric Detection at a L-Cysteine-Modified Gold Microdisk Array Electrode

Abstract

Capillary zone electrophoresis was employed for the analysis of cytochrome c using an end-column amperometric detector with a L-cysteine-modified gold microdisk array electrode. The optimum conditions of separation and detection are 0.04 mol/L KH₂PO₄ - 0.06 mol/L Na₂HPO₄ for the buffer solution, 8 kV for the separation voltage, 4 kV and 10 s for the injection voltage and the injection time, and −0.12 V vs. SCE for the detection potential. When the fused-silica capillary modified by ethylene glycol was used, the adsorption of cytochrome c on the surface of the capillary wall could be overcome. The limit of detection is 3 × 10⁻⁵ mol/L or 62 fmol (S/N = 2). The method was applied to determining cytochrome c in pig heart.

Key Words:

• Capillary zone electrophoresis
• Electrochemical detection
• Cytochrome c
• Modified electrode