Abstract
Laser-reduced graphene oxide (LRGO) on a polyethylene terephthalate (PET) substrate was prepared in one step to obtain the LRGO grid electrode for sensitive carbaryl determination. The grid form results in a grid distribution of different electrochemically active zones affecting the electroactive substance diffusion towards the electrode surface and increasing the electrochemical sensitivity for carbaryl determination. Carbaryl is electrochemically irreversibly oxidized at the secondary amine moiety of the molecule with the loss of one proton and one electron in the pH range from 5 to 7 by linear scan voltammetry (LSV) on the LRGO grid electrode with a scan rate of 300 mV/s. Some interference of the juice matrix molecules does not significantly affect the LSV oxidation current of carbaryl on the LRGO grid electrode after adsorptive accumulation without applied potential. The LRGO grid electrode can be used for LSV determination of carbaryl in fruit juices in the concentration range from 0.25 to 128 mg/L with LOD of 0.1 mg/L. The fabrication of the LRGO grid electrode opens up possibilities for further inexpensive monitoring of carbaryl in other fruit juices and fruits.