A glassy carbon electrode modified with graphene, gold nanoparticles and chitosan for ultrasensitive determination of lead(II).

We have modified a glassy carbon electrode by single-step electrodeposition of graphene (GR), gold nanoparticles (AgNPs), and chitosan (CS) directly from a solution containing graphene oxide, tetrachloroauric acid, and chitosan. The surface and electrochemical properties of the film-modified electrode were investigated by SEM and TEM images. The AuNPs have a diameter of about 20 nm and are uniformly dispersed in the matrix. Combining the advantages of GR (i.e., high surface area and conductivity), of AuNPs (excellent electrical conductivity) and CS (excellent film-forming ability and good water permeability), the hybrid film effectively enhances electron-transfer and promotes the response to lead(II) ion. Under the optimum conditions, a linear relationship exists between electrical current and the concentration of lead (II) ion in the range between 0.5 to 100 μg L-1, with a detection limit of 1 ng L-1 (at an SNR of 3). The electrode was successfully applied to the detection of lead(II) in spiked samples of river water. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]