Highly sensitive electrochemical determination of sulfate in PM2.5 based on the formation of heteropoly blue at poly-l-lysine-functionalized graphene modified glassy carbon electrode in the presence of cetyltrimethylammonium bromide

Abstract 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 μM for sulfate concentration with the coefficient of determination of 0.9996 and a detection limit of 0.26 μM. The proposed sensor was further employed to detect sulfate in fine particles (PM 2.5 , particulates with aerodynamic diameters