Benefits of HPLC-ICP-MS coupling for mercury speciation in food

Importance of the topic

Mercury is a highly toxic element whose species distribution determines its bioavailability and health risk in food. Speciation analysis is crucial for assessing human exposure, as methylmercury is far more toxic than inorganic forms. Conventional GC-based techniques require derivatization and lengthy preparation, driving interest in direct liquid chromatographic separation coupled to ICP-MS for rapid, sensitive detection without complex sample modification.

Objectives and study overview

This study evaluates the performance of a hyphenated HPLC-ICP-MS system for mercury speciation in food matrices. The key aims are to develop and validate a fast gradient separation for inorganic mercury (Hg2+), methylmercury (MeHg+), ethylmercury (EtHg+), and phenylmercury (PhHg+), and to demonstrate accuracy using certified reference materials (CRMs) from tuna muscle and dogfish liver.

Methodology and instrumentation

Sample preparation employs microwave-assisted extraction of 150 mg tissue in a cysteine-based buffer, followed by filtration. Chromatographic separation uses an Agilent 1260 HPLC with a Zorbax C-18 column (4.6×50 mm, 1.8 µm) under a methanol gradient to accelerate elution. Detection is performed on an Agilent 7700x ICP-MS with oxygen addition to the plasma for stable operation in organic-rich mobile phases and measurement at the 201Hg isotope.

Main results and discussion

Under optimized gradient conditions (2 % to 90 % methanol over 1 min), all four species separate within three minutes with no loss of plasma stability. Calibration curves from 0.1 to 10 µg/L exhibit excellent linearity and background equivalent concentrations below 20 ng/L. Analysis of BCR-464 and Dolt-4 CRMs yields methylmercury recoveries ≥96 % and inorganic mercury results consistent with expected values, confirming the method’s accuracy and robustness.

Benefits and practical application

• Eliminates derivatization and extensive cleanup, reducing analysis time and cost.
• Achieves rapid species separation with high sensitivity and low detection limits.
• Integrates seamlessly via MassHunter software for synchronized HPLC and ICP-MS control.

Future trends and opportunities

Advances in plasma frequency-matching and robust interfaces will enable broader use of organic solvent gradients and expanded speciation panels. Miniaturized and high-throughput HPLC-ICP-MS platforms may facilitate on-site testing and routine monitoring in food safety laboratories. Method extensions to trace-level detection of emerging organometallic contaminants will further enhance risk assessment capabilities.

Conclusion

The developed HPLC-ICP-MS method delivers fast, accurate mercury speciation in food with simplified sample preparation and robust performance. Validation against certified materials confirms reliability for routine toxicological assessment, offering an efficient alternative to GC-based protocols.

References

• Hight SC, Cheng J. Analytica Chimica Acta. 2006;567:160–172.
• Sannac S, Labarraque G, Fiscaro P, Pannier F, Potin Gautier M. Accred Qual Assur. 2009;14:263–267.