A nanosilica/exfoliated graphene composite film-modified electrode for sensitive detection of methyl parathion

Graphene nanosheets (GS) were easily prepared through liquid-phase exfoliation of graphite powder in N,N-dimethylformamide (DMF) with the assistance of sodium citrate. Then, GS was coated onto a glassy carbon electrode (GCE) surface by drop to fabricate a GS/GCE nanointerface. Subsequently, by using tetraethylorthosilicate sol as precursor, nanosilica was electrochemically deposited onto the GS/GCE surface to produce a nanocomposite film electrode (nanosilica/GS/GCE). Electrochemical behaviors of methyl parathion (MP) on the nanosilica/GS/GCE surface were investigated thoroughly. It was found that the nanosilica/GS nanocomposites can improve the redox peak currents of MP significantly due to the synergetic effect. The oxidation peak current was linearly related to MP concentration in the range from 0.0005 μmol/L to 5.6 μmol/L. The detection limit was calculated to be 0.07 nmol/L (S/N=3). The developed method was used to determine MP in real samples. The recoveries were in the range from 95.4% to 104.2%, demonstrating satisfactory results.