Online anion exchange column preconcentration and high performance liquid chromatographic separation with inductively coupled plasma mass spectrometry detection for mercury speciation analysis

• Hg+, MeHg, EtHg and Hg2+ were enriched by the SAX column preconditioned with sodium 3-mercapto-1-propanesulfonate.
• The enrichment factors of 1025–1108 were obtained using 6 mL sample in a 1.5-min enrichment procedure.
• Rapid separation was achieved within 5 min on a 50-mm C18 column using 0.5% (v/v) 2-mercaptoethanol as the mobile phase.
• MeHg, EtHg and Hg2+ concentrations at sub ng L−1 to sub μg L−1 levels were detected in the water.

A hyphenated method for mercury speciation analysis by the coupling of high performance liquid chromatography and inductively coupled plasma mass spectrometry with the online strong anion exchange column (SAX) preconcentration was developed. The Hg analytes (Hg+, MeHg, EtHg and Hg2+) were absorbed on the SAX column preconditioned with sodium 3-mercapto-1-propanesulfonate, and then rapidly eluted (less than 16 s) by 5 μL 3% (v/v) 2-mercaptoethanol. The enrichment factors of 1025 for Hg+, 1084 for MeHg, 1108 for EtHg and 1046 for Hg2+ were obtained using 6 mL sample in a 1.5-min enrichment procedure. Rapid separation of the four mercurial compounds was achieved within 5 min on a 50-mm C18 column using 0.5% (v/v) 2-mercaptoethanol as the mobile phase. The detection limits for Hg+, MeHg, EtHg and Hg2+ were 0.015, 0.010, 0.009 and 0.016 ng L−1, each, and the relative standard deviations of peak height and peak area (5 ng L−1 for each Hg species) were all below 5%. Mercury speciation in three freshwater, two drinking water and two seawater samples were then analyzed by the proposed method. MeHg and Hg2+ concentrations down to 0.14 and 0.56 ng L−1 were detected in the drinking waters.

This work demonstrated the online mercury preconcentration by a strong anion exchange guard column, followed by high performance liquid chromatographic separation and inductively coupled plasma mass spectrometry detection. The mercury species were enriched by around 1000-fold using 6 mL sample in a 1.5-min enrichment procedure.Figure optionsDownload as PowerPoint slide