Determination of mercury species by the diffusive gradient in thin film technique and liquid chromatography – atomic fluorescence spectrometry after microwave extraction

• DGT–MAE–LC–CV-AFS method was developed for determination of four mercury species.
• The microwave extraction was used for isolation of mercury species from resin gels.
• Optimized DGT–MAE–LC–CV-AFS method provides low detection limits (13–38 ng L−1).
• The diffusion coefficients of four mercury species were simultaneously determined.

A diffusive gradient in thin films technique (DGT) was combined with liquid chromatography (LC) and cold vapor atomic fluorescence spectrometry (CV-AFS) for the simultaneous quantification of four mercury species (Hg2+, CH3Hg+, C2H5Hg+, and C6H5Hg+). After diffusion through an agarose diffusive layer, the mercury species were accumulated in resin gels containing thiol-functionalized ion-exchange resins (Duolite GT73, and Ambersep GT74). A microwave-assisted extraction (MAE) in the presence of 6 M HCl and 5 M HCl (55 °C, 15 min) was used for isolation of mercury species from Ambersep and Duolite resin gels, respectively. The extraction efficiency was higher than 95.0% (RSD 3.5%). The mercury species were separated with a mobile phase containing 6.2% methanol + 0.05% 2-mercaptoethanol + 0.02 M ammonium acetate with a stepwise increase of methanol content up to 80% in the 16th min on a Zorbax C18 reverse phase column. The LODs of DGT–MAE–LC–CV-AFS method were 38 ng L−1 for CH3Hg+, 13 ng L−1 for Hg2+, 34 ng L−1 for C2H5Hg+ and 30 ng L−1 for C6H5Hg+ for 24 h DGT accumulation at 25 °C.

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