Sensitive Detection of H<,2>O<,2> by Electrochemiluminescence (ECL) of Luminol with a Microfluidic Chip Flow Electrolysis Cell

摘要

Sensitive detection of H<,2>O<,2> by Luminol electrochemiluminescence (ECL) is presented taking advantage of a new microfluidic flow electrolysis cell of only 300nl volume. Both cathode and anode were positioned parallel along the 2 sides of the channel. One ECL peak around 0.7V vs. Pt pseudo reference was observed in a CV scan with 2-electrode configuration. It was confirmed that electrochemical oxidation of both luminol and H<,2>O<,2> to radicals occurred on the anode, and photons were produced during luminol chemiluminescence (CL) reaction in homogeneous phase near anode; on the other hand, photon production through O<,2> route subjected to extra reaction steps, involving consumption of luminol radical liquid phase near anode to form a oxygen radical, and the oxygen radical reacted with another luminol radical to form the intermediate product to release photons, which explains the low efficiency of luminol ECL with O<,2> comparing to that of H<,2>O<,2>. Detection limit of H<,2>O<,2> down to pM level was obtained taking advantage of the enhancement effect on luminol ECL with the flow cell.