▎ 摘　　要

The paper presents novel analytical methods for sensitive mercury determination in various samples, i.e., waters, beverages, seafood, plants, and biological samples. The procedure is based on selective preconcentration/separation of Hg(II) ions using graphene oxide/thiosemicarbazide in dispersive micro-solid phase extraction (DMSPE) and detection by energy-dispersive (EDXRF) and total-reflection X-ray fluorescence spectrometry (TXRF). The DMSPE/EDXRF and DMSPE/TXRF procedures are characterized by very high enrichment factors and low detection limits (LODs). DMSPE/TXRF allows obtaining LODs of 2.1 pg mL(-1) for liquids and 1.8 ng g(-1) for solid samples. In the case of DMSPE/EDXRF, the LODs are higher, 60 pg mL(-1) for liquid and 73 ng g(-1) for solid samples, due to the worse sensitivity of EDXRF measurement. The method was validated using spiked samples (water, apple juice, beer, wine) and certified reference materials (seawater, groundwater, wastewater, herring, cormorant and cod tissues, pig kidney, lobster, tobacco, scallion, celery, and spinach).