Electrochemical nitric oxide microsensors: sensitivity and selectivity characterisation

In this study, we have prepared two nitric oxide (NO) microsensors using tw o combinations of nickel tetrasulfonated phthalocyanine (NiTSPc), o-phenyle nediamine (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/Nafio n(R)/o-PD, respectively) in our home made operating conditions. We have dev eloped 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 coating s and the sensitivity of the examined microsensors. By comparing the permea bility of the microsensors to various interfering analytes, such as L-argin ine, ascorbate, nitrite, serotonine, dopamine, acetamidophenol, 4-met-catec hol, epinephrine, norepinephrine, dopac and 5-hydroxyindol, we have discuss ed the molecular sieving exclusion of the deposited membranes in term of mo lecular weight cutoff (MWCO). (C) 2000 Elsevier Science B.V. All rights res erved.