Simultaneous Mercury and Tin Speciation using GC-HR-ICP-MS

Significance of the Topic

Capillary gas chromatography coupled with high‐resolution ICP‐MS enables the ultra‐trace determination of mercury and tin species, critical for assessing their toxicity, mobility and environmental fate.

Objectives and Study Overview

This application note describes the development of a simultaneous speciation method for mercury and tin compounds. The goal is to separate and quantify ethylated derivatives of inorganic and organic species at sub‐ppt levels using GC‐HR‐ICP‐MS.

Methodology and Instrumentation

• GC System: TRACE GC Ultra with AS3000 autosampler, PTV splitless inlet.
• ICP‐MS: ELEMENT 2 high‐resolution instrument with GC Interface Kit for dual aqueous/volatile introduction.
• Sample Introduction: Glass Expansion MicroMist nebulizer, Twinnabar mini‐cyclonic spray chamber, nickel cones.
• Chromatographic Conditions: TR-5 column (30 m × 0.25 mm, 0.25 µm), He carrier gas, 50 °C to 300 °C temperature program.
• Derivatization: Sodium tetraethylborate ethylation in acetate buffer; extraction into hexane.
• Internal Standards: Continuous aspiration of Sb and Tl (5 ng/mL) for plasma stability and sensitivity monitoring.
• Data Processing: ELEMENT Method software for acquisition; Xcalibur for peak integration, calibration and quantification.

Main Results and Discussion

• Clear separation of nine species (MeHg⁺, Hg²⁺, InSn, MBT, DBT, TBT, MPhT, DPhT, TPhT) in a 14 min run time.
• Limits of detection in the low to sub-ppt range (LOD 0.7–7.3 ng/L); blank equivalent concentrations reveal reagent‐derived backgrounds.
• Robust plasma performance achieved via dual‐mode sample introduction, ensuring stable signals.
• Tributyltin contamination in reagents highlighted the importance of purity checks for ultra‐trace analysis.

Benefits and Practical Applications

• Simultaneous multi‐element speciation of mercury and tin in water, sediments, biota and seawater.
• High throughput with rapid analysis and straightforward sample preparation.
• Ultra‐trace sensitivity supports regulatory compliance, environmental monitoring and biogeochemical research.

Future Trends and Opportunities

• On‐line derivatization and pre‐concentration to further lower detection limits.
• Expansion to other toxic metal species and transformation products in diverse matrices.
• Advances in GC‐ICP interfaces and plasma stability to enhance quantification in complex samples.

Conclusion

The GC‐HR‐ICP‐MS method provides a powerful, reliable approach for simultaneous ultra‐trace speciation of mercury and tin, meeting critical needs in environmental analysis and research.

Reference

No formal literature references were provided in the source application note.