Voltammetric detection of 2-aminoazotoluene based on electropolymerization of β-cyclodextrin

The voltammetric behavior of 2-aminoazotoluene (2-AMAT) is studied at pencil electrode (PEC) modified by electropolymerization of β-cyclodextrin (P-β-CD-PEC) in different supporting electrolyte at various pH values using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). At the scan rate of 0.1 V s −1 , 2-AMAT exhibits an irreversible oxidation peak at 0.67 V in phosphate buffer solution (PBS) with the pH value of 6.64. The electrochemical data suggest that the oxidation reaction of 2-AMAT at the surface of P−β−CD−PEC involves one electron and one proton. 2−AMAT has a significantly higher oxidation peak current on P−β−CD−PEC than pristine PEC, which is ascribed to the presence of cavities in polymer of β−CD on the surface of PEC. Under the optimized DPV conditions, the oxidation peak current is linear with 2-AMAT concentration in the range of 0.3 μM to 30.0 μM with a low limit of detection (LOD = 0.14 μM) and high sensitivity (1.45 μA /μM). The same 2-AMAT concentration was measured every two days in 20 days using the same P−β−CD−PEC. The results show that the relative standard deviation (RSD) of the peak current was 3.36%, indicating that the stability of P−β−CD−PEC is good. Five different bitches P−β−CD−PEC was used to determine the same 2-AMAT concentration and 4.29% RSD is obtained, which suggests that the reproducibility of this modified electrode is excellent. In addition to some metal ions, the structural substances such as 2,4-diaminotoluene and 4-chloroaniline do not interfere the determination of 2-AMAT, suggesting that P−β−CD−PEC has fine selectivity. Therefore, a new method for detecting 2-AMAT based on P−β−CD−PEC is developed. This method is successfully used to determine 2−AMAT in rose lotion cosmetics with satisfied results.