The simultaneous electrodetection of indole and 3methylindole 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 LiClO 4 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 mM with the limits of detection (LOD) found to be 3 Â 10 À2 mM for indole and 5 Â 10 À2 mM 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.

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We report on the development of sensor arrays comprising synthetic boron doped diamond (BDD) electrodes modified with metal catalyst nanoparticles. The latter are deposited onto the BDD electrodes surface by a physical vapor deposition process followed by de-wetting under oxygen-free atmosphere in high temperature conditions. The mean size of the particles is in the order of 10 nm, as characterized by scanning electron microscopy (SEM) image processing and small-angle X-ray scattering (SAXS). The particles are made of e.g. platinum, iridium, gold, ruthenium or alloys thereof and showed good adhesion, and good electrochemical reactivity towards a wide range of redox analytes. Sensor arrays composed of 4 BDD electrodes each modified with a different nano-catalyst were mounted and tested for various analytical applications. For instance such a sensor array was able to detect online and discriminate the presence in tap water of the following contaminants: Imidacloprid, Dimethyl methylphosphonate (DMMP) or hydrogen peroxide, chosen for demonstration purpose.

Abstract:Boron Doped Diamond (BDD) electrodes exhibit excellent properties including a wide potential window in aqueous media, high corrosion resistance, chemical inertness, bio-compatibility and low background current. In order to increase their selectivity for analytical applications, several studies were carried out recently on the possibility to deposit metal nanoparticles such as Pt or Ir on such BDD electrodes1,2,3,4. Indeed these nanoparticles bring interesting electro-catalytic properties to the electrodes, thus offering the possibility to address new analytes. Here an electrode array was developed, based on multiple BDD electrodes casted with various metal nanoparticles. The simultaneous detection of analytes by each electrode composing the array gives potentially a unique fingerprint to the analytes, thus increasing the specificity and the selectivity of the sensor.