A novel non-enzyme amperometric platform based on poly(3-methylthiophene)/nitrogen doped graphene modified electrode for determination of trace amounts of pesticide phoxim

• A novel non-enzyme sensor based on poly(3-methylthiophene)/nitrogen doped graphene was constructed for determination of phoxim.
• Ultrasensitive determination of phoxim was achieved with a detection limit of 6.4 nM.
• High selectivity of the proposed sensor platform was demonstrated.
• The easy fabrication and manipulation of the non-enzyme platform make it possible to achieve industrialization.

Poly(3-methylthiophene)/nitrogen doped graphene modified glassy carbon electrode (P3MT/NGE/GCE) was prepared through simple drop-casting of NGE, followed by the electrodeposition of P3MT film for sensitive electrochemical determination of trace amounts of pesticide phoxim. The morphology and structure of P3MT/NGE/GCE were characterized by scanning electron microscopy; the electrochemical behavior of P3MT/NGE/GCE was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and chronocoulometry. The preparation conditions of modified electrode, the dropping amount of NGE and polymerization laps of P3MT, were optimized. Under the optimized conditions, the reduction peak current of cyclic voltammetric curve varied linearly with the concentration of phoxim over the two linear ranges of 0.02–0.2 μM and 0.2–2.0 μM, and the low detection limit was 6.4 nM according to lower linear range (S/N = 3). The sensor also exhibited excellent selectivity to phoxim over a wide range of possible interferents including ions, biomolecules, common environment pollutants and widely-used organophosphate pesticides. Moreover, the satisfactory practical feasibility of the sensor was evaluated by the environmental phoxim measurements.