A novel electrochemical sensor, 4-aminophenol (4-AP), was generated by electrodeposition of poly-L-glutathione (P-L-GSH) onto reduced graphene oxide (RGO) to form a RGO/P-L-GSH composite matrix on a glassy carbon electrode (RGO/P-L-GSH/GCE). The morphology and structure of RGO/P-L-GSH modified GCE were characterized by scanning electron microscopy (SEM), FT-IR spectroscopy and electrochemical impedance spectroscopy. As an electrochemical sensor, the RGO/P-L-GSH modified GCE composite exhibited strong catalytic activity toward the oxidation of 4-AP by cyclic voltammetry (CV) and chronoamperometry.Furthermore, the electrochemical sensor exhibited an excellent current response for 4-AP over a wide linear range of 0.4 to 200 µM (R 2 = 0.9934) with a lower detection limit (LOD ) of 0.03 µM (S/N = 3), as well as a sensitivity of 27.2 (µA µM -1 cm -2 ) and excellent selectivity, reproducibility and stability. The electrochemical sensor demonstrated good anti-interference ability in the presence of glucose, fructose, paracetamol, ethanol, l-isoluecine, l-histidine, lcysteine, dopamine, l-serine, l-tyrosine, phenylalanine, urea, hydrogen peroxide, K + , Ca 2+ , Na + , F -, SO 4 2-, Cu 2+ , Fe 3+ , Zn 2+ , SO 4 2-, SO 3 2-, Cl -, folic acid and ascorbic acid. The proposed electrochemical method was successfully applied to produce a sensor for the detection of 4-AP in juice and water samples. sensitivity and very low LOD for amperometric determination of 4-AP when compared to most other sensors reported in recent years.The 4-AP sensor was also applied for analysis of juice and water samples, and the results showed it was useful in practical applications.
Experimental Section
ReagentsThe graphite (powder, <20 lm), L-glutathione, 4-aminophenol, Na 2 HPO 4 and NaH 2 PO 4 , were received from the Sigma ChemicalCompany. In addition a 0.05 M phosphate buffer solution (PBS, pH 7) was used as the supporting electrolyte. Other chemicals were of analytical reagent grade, and all aqueous solutions were prepared with double distilled water for use in the experiments.
ApparatusAll the electrochemical measurements were executed on a CHI 405A electrochemical workstation (Shanghai Chenhua Instrument, China).A conventional three-electrode system was used with an RGO/P-L-GSH film modified electrode as the working electrode, a platinum wire as the auxiliary electrode and a saturated Ag/AgCl as the reference electrode. Electrochemical impedance spectroscopy (EIS) was carried out in a frequency range of 0.