Amperometric detection for capillary electrophoresis at a sol–gel carbon composite electrode

Abstract

The application of a newly developed sol–gel carbon composite electrode (CCE) was evaluated for the amperometric detection in capillary electrophoresis (CE). A sol–gel CCE of ca. 150 μm diameter was employed as a detector in a wall-jet arrangement. The use of simple anodic electrochemical pre-treatment at +1.80 V versus SCE for 2 min was shown to produce an improved and reasonably stable electrode response compared to that of the untreated electrode. Although, the enhancement resulting from electrochemical pre-treatment was not permanent, the results obtained under CE conditions demonstrated that the sol–gel CCE with a single electrochemical pre-treatment was suitable for CE applications. Following the electrochemical pre-treatment, a sample mixture containing dopamine, catechol, epinephrine and norepinephrine was separated in a CE system. The calibration graphs for all these neurotransmitters were found to be linear in the range 1–400 μM and the detection limit (signal/noise = 3) for each neurotransmitter examined was <350 amol.