HIGHLY SENSITIVE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY DETECTION OF CATECHOLAMINE WITH INTERDIGITATED ARRAY MICROELECTRODES

Interdigitated array (IDA) microelectrodes in which both the band width and gap are 2 mum were fabricated and applied to the electrochemical detectors used in flow injection analysis (FIA) and high-performance liquid chromatography (HPLC). The steady-state limiting current measured by FIA consists of the one-third power flow dependent current and the flow independent current. This flow independent current is caused by redox cycling. When an IDA electrode is used, the current density is about ten times greater than with an ordinary glassy carbon disk electrode. The high current density and low background noise allowed the detection of 100 pM (2 fmol) of dopamine by HPLC measurement. It was found that the peak current and sample concentration had a linear relationship over a wide range (from 100 pM to 10 muM).