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 donated 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 mu g/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.