Picomolar-level detection of mercury within non-biological/biological aqueous media using ultra-sensitive polyaniline-Fe

Mercury as the 3rd most toxic, non-biodegradable, and carcinogenic pollutant can adversely affect the ecosystem and health of living species through its bioaccumulation within the nature that can affect the top consumer in the food chain; therefore, it is vital to sense/remove Hg2+ within/from aqueous media using practical approaches. To address this matter, we modified the glassy carbon electrode (GCE) with ultra-sensitive, interconnected, sulfurized, and porous nanostructure consisted of polyaniline-Fe3O4-silver diethyldithiocarbamate (PANi-F-S) to enhance the sensitivity, selectivity, and limit of detection (LOD) of the sensor. Obtained results showed that at optimum conditions (i.e., pH value of 7, deposition potential of - 0.8 V, and accumulation time of 120 s), for Hg2+ concentration ranging from 0.4 to 60 nM, the modified electrode showing linear relative coefficient of 0.9983, LOD of 0.051 nM, LOQ of 0.14 nM, and sensitivity of 1618.86 μA μM-1 cm-2 highlights superior sensitivity of the developed platform until picomolar level. Additionally, the modified electrode showed ideal repeatability, stability, reproducibility, and selectivity (by considering Zn2+, Cd2+ Pb2+, Cu2+, Ni2+, and Co2+ as metal interferences) and recovered more than 99% of the Hg2+ ions within non-biological (mineral, tap, and industrial waters) and biological (blood plasma sample) fluids. Graphical abstract.