Electrocatalytic oxidation and sensitive determination of N-acetyl-L-cysteine at cyclodextrin-carbon nanotubes modified glassy carbon electrode

Abstract

The electrochemical behavior and electroanalysis of N-acetyl-L-cysteine (NAC) were studied at a glassy carbon electrode modified with β-cyclodextrin (β-CD) and carbon nanotubes (β-CD/MWCNT/GCE). The β-CD/MWCNT/GCE displayed excellent electrocatalytic performance to the catalytic oxidation reactions of NAC. Because NAC is selectively enriched by β-CD, the β-CD/MWCNT/GCE can solve the problems of the signal attenuation caused by the adsorption of the NAC oxidation product. The influence of the experimental conditions on the NAC electrochemical behavior was also considered, when using a modified electrode. The mechanism and kinetics of the catalytic oxidation reactions of NAC were monitored by the cyclic voltammetry and chronoamperometry. The catalytic oxidation rate constant k (4.21 ± 0.05) × 103 M−1 s−1 was calculated using electrochemical approaches. The results showed that in 1.0 × 10−3 M of potassium ferricyanide solution, the current signals were proportional to the NAC concentration from 4.4 × 10−4 M to 8.0 × 10−2 M [I p (10−6 A) = 0.58412 + 5.38 × 103 c(M), R 2 = 0.9934], and the detection limit (S/N = 3) was 5.02 × 10−5 M. For 80 mM NAC, six successive measurements yielded R.S.D. of 3.4%, which shows that the sensor is reproducible. The proposed method can be applied for the determination of NAC in routine analysis.