SUCCESSFUL LOW LEVEL MERCURY ANALYSIS

Significance of the topic

Mercury is a rare heavy metal recognized for its multiple industrial applications and high toxicity across inhalation, ingestion, and dermal exposure routes. Its presence is regulated in matrices such as drinking water, seafood, pharmaceutical products and consumer goods. Reliable monitoring of trace-level mercury is critical for environmental safety and public health.

Objectives and overview of the study

This study demonstrates a streamlined method for integrating mercury determination into routine multi-element analysis by ICP-MS. It evaluates the optimization of plasma conditions, sensitivity enhancement and sample preservation strategies to achieve ppt-level detection while maintaining high sample throughput.

Methodology and sample preparation

To improve mercury ionization, the plasma is operated at elevated temperature, indicated by a low CeO+/Ce+ ratio. Sample stability is secured by adding 0.5 to 1.0% hydrochloric acid, promoting formation of the [HgCl4]2- complex and minimizing volatilization losses. Closed-vessel digestion is employed alongside acidification to preserve element integrity.

Used instrumentation

• Agilent 7800 Quadrupole ICP-MS
• Universal helium collision mode for removal of chloride-based interferences

Main results and discussion

Implementation of helium mode in the collision/reaction cell effectively suppresses polyatomic interferences arising from chloride matrices, eliminating the need for multiple reactive gases. Calibration with the 201Hg isotope (13.18% abundance) yields a linear response across ng/L (ppt) levels. A detection limit of approximately 1.5 ppt and a background equivalent concentration of 9.5 ppt were achieved, confirming reliable quantitation at single-ppt concentrations.

Benefits and practical applications of the method

• Enables simultaneous multi-element analysis including mercury without dedicated single-element instrumentation
• Simplified sample preparation using low-level HCl ensures stability and consistent recovery
• Routine measurement down to single ppt levels supports environmental, food safety and pharmaceutical quality control
• Universal helium mode reduces method development time and gas consumption

Future trends and applications

Ongoing developments in collision cell technology and sample introduction are expected to further lower detection limits and simplify workflows. Emerging trends include automated sample handling, on-site portable ICP-MS systems and integration with speciated mercury analysis. These advances will expand the applicability of low-level mercury monitoring across environmental, industrial and clinical settings.

Conclusion

The optimized use of the Agilent 7800 ICP-MS with helium collision mode and an HCl-based preservation strategy provides a robust, high-throughput solution for trace mercury analysis. The approach achieves single-ppt detection capabilities within a multi-element framework, streamlining regulatory compliance and routine monitoring in diverse matrices.

Reference

• Agilent Technologies. Application note 5990-7173EN, June 2015.