Sulfhydryl-functionalised magnetic nanoparticles as sorbent in dispersive solid-phase extraction for the rapid enrichment of mercury species from natural water samples

The sulfhydryl-functionalised core-shell Fe3O4@SiO2 magnetic nanoparticles (Fe3O4@SiO2-RSH MNPs)-based dispersive solid-phase extraction method was developed. The goal of this method is the extraction of mercury species from natural water samples. An interesting aspect of the method is that, thanks to the spontaneously aggregate, the MNPs with a sub-30-nm-size range could be fast and efficiently extracted by 0.45 m pore size mixed cellulose esters membrane filter. Thus, the elution step can be conducted by passing small amounts eluent through the MNPs on the membrane. It is also found that addition of Ag+ to water sample could improve the elution efficiency, and furthermore, minimises the matrix effects during the extraction of mercury species from natural water samples. The feasibility of the method was studied, and extraction efficiency was evaluated. The results showed that, calculated at 5 ng/L spiked concentration levels, absolute recoveries were 89.4%, 91.9% and 64.2%, and enrichment factors (EFs) were 596, 613 and 428, for inorganic mercury, methylmercury and ethylmercury, respectively. The high EFs were achieved in 5min of overall extraction time. The method was applied to groundwater and river water samples. The results showed that its suitability for use in fast extracting trace levels of mercury species from natural water samples.