Sensitive and Selective Electrochemical Analysis of Methyl‐parathion (MPT) and 4‐Nitrophenol (PNP) by a New Type p‐NiTSPc/p‐PPD Coated Carbon Fiber Microelectrode (CFME)

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 −1 in the concentration range 0.01 to 10 mg/L with a detection limit of 40 μg/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.