Speciation analysis of mercury in sediments,zoobenthos and river water samples by high-performance liquid chromatography hyphenated to atomic fluorescence spectrometry following preconcentration by solid phase extraction

摘要

A high-pressure microwave digestion was applied for microwave-assisted extraction (MAE) of mercury species from sediments and zoobenthos samples.A mixture containing 3 mol L~(-1) HC1,50% aqueous methanol and 0.2 mol L~(-1) citric acid (for masking co-extracted Fe~(3+)) was selected as the most suitable extraction agent.The efficiency of proposed extraction method was better than 95% with R.S.D.below 6%.A preconcentration method utilizing a "homemade" C18 solid phase extraction (SPE) microcolumns was developed to enhance sensitivity of the mercury species determination using on-column complex formation of mercury-2-mercaptophenol complexes.Methanol was chosen for counter-current elution of the retained mercury complexes achieving a preconcentration factor as much as 1000.The preconcentration method was applied for the speciation analysis of mercury in river water samples.The high-performance liquid chromatography-cold vapour atomic fluorescence spectrometric (HPLC/CV-AFS) method was used for the speciation analysis of mercury.The complete separation of four mercury species was achieved by an isocratic elution of aqueous methanol (65%/35%) on a Zorbax SB-C18 column (4.6 mm x 150 mm,5mu m) using the same complexation reagent (2-mercaptophenol).The limits of detection were 4.3 mu gL~(-1) for methylmercury (MeHg~+),1.4 mu g L~(-1) for ethylmercury (EtHg~+),0.8 mu gL~(-1) for inorganic mercury (Hg~(2+)),0.8 mu gL~(-1) for phenylmercury (PhHg~+).