Electrochemical Behavior of a Thio-Quinazoline Derivative Electrodeposited on a Glassy Carbon Electrode Modified with Multi-Wall Carbon Nanotubes: Application for Simultaneous Determination of Hydroxylamine and Nitrite

In this paper, we report the characteristics of a modified electrode prepared by electrodeposition of anthio-quinazoline derivative on the multi-wall carbon nanotubes modified glassy carbon electrode (QMWCNT-GCE). The charge transfer coefficient, alpha, was calculated to be 0.43, and the charge transfer rate constant, k(s), was 12.6 +/- 0.3 s(-1) in pH 7.0 between thio-quinazoline and MWCNT-GCE. The reactivity of this modified electrode for electrocatalytic oxidation of hydroxylamine was also examined. The results show that the sensitivity of hydroxylamine determination at a QMWCNT-GCE is remarkably improved and its overpotential is reduced when compared to MWCNT-GCE and QMGCE. By cyclic voltammetry, the kinetic parameters of electron transfer coefficient, alpha, the heterogeneous electron transfer rate constant, k', and the exchange current, i(0), for the oxidation of hydroxylamine at the QMWCNT-GCE surface were calculated. Linear calibration curves were obtained for 3.0-69.8 mu M and 69.8-915.2 mu M of hydroxylamine at the modified electrode surface using an amperometric method. Also, the amperometric method exhibited the detection limit of 0.83 mu M for hydroxylamine. The results indicate that the modified electrode is sensitive to hydroxylamine in the presence of nitrite (NO2-). Finally, the modified electrode was successfully applied for determination of hydroxylamine and NO2- in two water samples.