Simultaneous detection of indole and 3-methylindole using boron-doped diamond electrodes

The simultaneous electrodetection of indole and 3-methylindole was investigated in this paper. The detection was performed using a boron-doped diamond ( BDD) electrode to take advantage of its remarkable electrochemical properties ( Fujishima et al., Diamond Electrochemistry ( Elsevier, 2005) [ 1]. In order to improve the selectivity between indole and 3-methylindole, square-wave voltammetry ( SWV) was used. We showed that BDD electrodes fouled either from oxidation of indole or 3-methylindole could be efficiently reactivated in LiClO4 aqueous solutions using trains of short anodic and cathodic pulses applied to the working electrode. We were able with this approach to measure simultaneously both indole and 3-methylindole in aqueous solutions in the range of 10-500 mu M with the limits of detection ( LOD) found to be 3 x 10(-2) mu M for indole and 5 x 10(-2) mu M for 3-methylindole. Both indoles were also detected successfully following extraction from pork fat. This work opens up the way toward systematic detection of indole and 3-methylindole in processed foodstuffs, with a strong industrial interest for the detection of boar taint in pork meat.