Ultrasensitive sensing of N-acetyl-L-cysteine using an electrocatalytic transducer of nanoparticles of iron(III) oxide core-cobalt hexacyanoferrate shell

The electrocatalytic oxidation of N-acetyl-L-cysteine (NAC) was studied on nanoparticles of iron(III) oxide core-cobalt hexacyanoferrate shell (Fe(2)O(3)@CoHCF)-modified carbon paste electrode (cs-MCPE). Voltammetric studies indicated that NAC was oxidized via a surface mediation electrocatalytic mechanism by Fe(2)O(3)@CoHCF. The catalytic rate constant, the electron-transfer coefficient and the diffusion coefficient involved in the electrooxidation process of NAC on Fe(2)O(3)@CoHCF were reported. Based on the electrocatalytic efficiency of Fe(2)O(3)@CoHCF, cs-MCPE was employed for the ultrasensitive sensing of the trace amounts of NAC. Linear sweep voltammetry (LSV) and amperometry techniques were developed for the analysis of NAC. For the former method, a linear dynamic range from 12.2 to 66.7 mu M with calibration sensitivity of 7.88 x 10(-2) A M(-1) cm(-2) and for the latter one, a linear dynamic range from 20 to 432 mu M with calibration sensitivity of 1.67 x 10(-2) A M(-1) cm(-2) resulted for NAC. Also, according to the proposed LSV and amperometry methods, NAC was determined with detection limits of 205 and 20.9 nM, respectively. The proposed amperometry method was also applied to the analysis of commercial tablets and injection samples. (C) 2009 Elsevier B.V. All rights reserved.