A simple and sensitive electrochemical sensor based on the formation of heteropoly blue at poly-L-lysine (PLL)-functionalized graphene (GR) modified glassy carbon electrode (GR-PLL/GCE) was developed to detect sulfate in the presence of cetyltrimethylammonium bromide (CTAB). This method was based on the oxidation currents of the blue complex formed via 40 s electrolysis of Mo (VI)-acetone-HCl solution containing sulfate at 0.1 V vs. SCE and sulfate concentration. The structure and morphology of GR, PLL and GR-PLL were examined by Raman, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The fabricated sensor was further characterized using cyclic voltammetry (CV). Under optimum conditions, the sensor displayed a wide linear range of 0.8-1000 mu M for sulfate concentration with the coefficient of determination of 0.9996 and a detection limit of 0.26 mu M. The proposed sensor was further employed to detect sulfate in fine particles (PM2.5, particulates with aerodynamic diameters <2.5 mu m). The results obtained were in good agreement with those of using ion chromatography (IC), which indicates that this novel voltammetric sensor has promising applications for the detection of sulfate in environmental fields. (C) 2016 Elsevier B.V. All rights reserved.