Ion-imprinted magnetic nanoparticles for specific separation and concentration of ultra-trace methyl mercury from aqueous sample

•A MeHg ion-imprinted magnetic nanoparticle was developed for rapidly extract ultra-trace MeHg from water.•It has better stability, specificity and a 25 mg MeHg/g of adsorption capacity.•It can specifically extract MeHg from water within 30 min with a recovery >95% and a 250 enrichment factor.•It can be used for simple and accurate detection of trace MeHg in water by combining with CE-ICP-MS.

For rapidly and sensitively determining ultra-trace methyl mercury (MeHg) in aqueous environment, we herein synthesized a MeHg ion-imprinted magnetic nanoparticle (MeHg IIMN) to simply and specifically extract/concentrate ultra-trace MeHg from water samples. The MeHg IIMN employed core-shell Fe3O4@SiO2 nanoparticles (Fe3O4@SiO2 NPs) as supporting structure, the complex ion of 1-pyrrolidinecarbodithioic acid and MeHg (PDC-CH3Hg+) as template, methacrylic acid (MAA) as functional monomer and trimethylolpropane trimethacrylate (TMPTM) as cross linker. The MeHg IIMN offered obvious advantages such as low cost, easy manipulation, better specificity and stability, and recycling characteristics. It can be used to separate/concentrate ultra-trace MeHg from natural water sample within 30 min with a recovery >95%, an enrichment factor of 250, a relative standard deviation (RSD, n = 5) <7%, a 25 mg MeHg/g of maximum adsorption capacity, 50 times of recycling, and without obvious interference of other ions. Combining with capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS), it can be used for the accurate detection of ultra-trace methyl mercury in natural water samples with a limit of detection of 0.084 pg/mL, a recovery of 92-99% and a RSD (n = 5) <8%. The success of this study promises a valuable technique for relatively simple detection of ultra-trace methyl mercury in aqueous environment.