A novel modified carbon fiber microelectrode (CFME) was obtained by combination of tetrasulfonated nickel phtalocyanine (p-NiTSPc) electroformed film associated to para-phenylenediamine (p-PPD) electropolymerized outer-coating. The modified CFMEs where denoted C/p-NiTSPc and C/p-NiTSPc/p-PPD, respectively. These electrodes are dedicated to the organophosphates compounds (OPs) methyl-parathion (MPT) and para-nitrophenol (PNP). Our contribution shows that both OPs can be determined simultaneously on the unmodified and modified C/ p-NiTSPc CFMEs. A clear electrocatalytic activity towards both MPT and PNP redox process was observed, for the first time, in presence of p-NiTSPc. The obtained sensitivity for the C/p-NiTSPc CFME was 80 nA L mg À1 in the concentration range 0.01 to 10 mg/L with a detection limit of 40 mg/L. Also the combination of p-NiTSPc and p-PPD electrodeposited films show, for the first time, the possibility to discriminate on the C/p-NiTSPc/p-PPD CFME between MPT and PNP. Stability experiments were also conducted for 3 weeks in acetate buffer showing a good reproductibility of the sensitivity to PNP vs. time in presence of MPT with a little loss of sensitivity (5%) after 3 weeks.

The release of reactive oxygen species (ROS) or reactive nitrogen species (RNS), i.e., the initial phase of oxidative stress, by macrophage cells has been studied by electrochemistry within a microfluidic device. Macrophages were first cultured into a detection chamber containing the three electrodes system and were subsequently stimulated by the microinjection of a calcium ionophore (A23187). Their production of ROS and RNS was then measured by amperometry at the surface of a platinized microelectrode. The fabricated microfluidic device provides an accurate measurement of oxidative release kinetics with an excellent reproducibility. We believe that such a method is simple and versatile for a number of advanced applications based on the detection of biological processes of secretion by a few or even a single living cell.