Synthesis of MoS₂ nanosheets for mercury speciation analysis by HPLC-UV-HG-AFS

Mercury species have aroused wide concern in the past several decades due to their high toxicity. However, it is still difficult to detect ultra-trace mercury species due to their biochemical transformation in complex samples. To establish a simpler and more sensitive method for pre-concentration and determination of trace mercury species, molybdenum disulfide (MoS₂) nanosheets with sulfur-rich characteristics and enlarged interlayer spacing were prepared by a hydrothermal method coupled with a sonication-assisted liquid exfoliation method and acted as solid-phase extraction adsorbent. The nano-MoS₂ had high adsorption capacity, fast adsorption rate and excellent selectivity towards mercury ions (Hg²⁺), methyl mercury (MeHg⁺) and ethyl mercury (EtHg⁺) in a wide pH range and complex matrices. And it could be easily regenerated by 4 mol L^-1 HCl and reused several times. After optimizing HPLC-UV-HG-AFS conditions, a great linearity (1.0-10.0 μg L^-1, R ² = 0.999 for Hg²⁺, MeHg⁺ and EtHg⁺), lower detection limits (0.017, 0.037 and 0.021 ng mL^-1 for Hg²⁺, MeHg⁺ and EtHg⁺, respectively), relative standard deviations (<5%) and addition recoveries of the samples within 82.75-113.38% were observed. In summary, trace inorganic and organic mercury species in environmental and biological samples could be selectively enriched by the prepared nano-MoS₂ and efficiently seperated and detected by HPLC-UV-HG-AFS. The present study will help provide a better strategy for environmental monitoring and health assessment of mercury pollutants.