Electrochemical nitric oxide microsensors:: sensitivity and selectivity characterisation

In this study, we have prepared two nitric oxide (NO) microsensors using two combinations of nickel tetrasulfonated phthalocyanine (NiTSPc), o-phenylenediamine (o-PD) and Nafion(R) based layers to modify the surface of 8 mu m diameter carbon fiber electrodes. We have compared the performances of the obtained composite microsensors (carbon/NiTSPc/Nafion(R), and carbon/Nafion(R)/o-PD, respectively) in our home made operating conditions. We have developed the sessile drop contact angle measurement technique as well as the use of the electrochemical quartz crystal microbalance (EQCM), differential normal pulse voltammetry (DNPV) and differential normal pulse amperometry (DNPA) to correlate the hydrophobicity, mass deposit of the polymer coatings and the sensitivity of the examined microsensors. By comparing the permeability of the microsensors to various interfering analytes, such as L-arginine, ascorbate, nitrite, serotonine, dopamine, acetamidophenol, 4-met-catechol, epinephrine, norepinephrine, dopac and 5-hydroxyindol, we have discussed the molecular sieving exclusion of the deposited membranes in term of molecular weight cutoff (MWCO). (C) 2000 Elsevier Science B.V. All rights reserved.