▎ 摘　　要

This work reports the development of a composite material containing graphene oxide and pectin (GO-PEC) to increase the lead signal during the analysis of biofuels through differential pulse anodic stripping voltammetry. To this end, a glassy carbon electrode was used as substrate for the immobilization of the GO-PEC composite. This electrode was characterized through cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, Raman spectroscopy and energy dispersive X-ray spectroscopy. The results obtained showed that the GO-PEC composite promoted a 90-fold increase in the intensity of the anodic stripping current of lead. The electrode containing the GO-PEC composite presented a linear range of 1.0 x 10-9 to 1.0 x 10-6 mol L-1 and a detection limit of 4.0 x 10- 10 mol L-1. This device also exhibited reproducible and stable voltammetric responses as well as excellent selectivity for lead detection. The proposed electrode was applied for the determination of lead in biodiesel and biokerosene samples. Recovery tests and flame atomic absorption spectroscopy analyses confirmed that this electrode has excellent precision and accuracy for lead detection. These results show that the electrode developed in this work can be successfully used for lead monitoring in biofuel samples.