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

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 6M HCl and 5M HCl (55 degrees 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 degrees C. (C) 2015 Elsevier B.V. All rights reserved.