Fast and Accurate Speciation of Mercury in Milk and Honey Food Products by HPLC-ICP-MS

Significance of the Topic

Mercury (Hg) is a persistent environmental toxin and one of the top public health concerns due to its bioaccumulation in food chains and variable toxicity depending on its chemical form. Milk and honey are widely consumed globally and subject to regulatory limits on total mercury and methylmercury (MeHg) to protect consumer health. This study addresses the need for rapid, robust speciation methods to ensure food safety compliance and accurate risk assessment.

Objectives and Study Overview

The objective was to develop and validate a fast, accurate HPLC-ICP-MS method using Agilent instrumentation for simultaneous determination of inorganic Hg (Hg2+) and MeHg in milk and honey, in accordance with Food Safety and Standards Authority of India (FSSAI) regulations and European Union guidelines.

Methodology

Samples of full-fat milk and commercial honey were diluted 20-fold in a mobile phase of 0.1% L-cysteine (pH 2.6), heated at 60 ± 2 °C, and filtered as required. Calibration standards of Hg2+ and MeHg were prepared over a 0–10 µg/L range. Chromatographic separation used a ZORBAX SB C-18 column (4.6×250 mm, 3.5 µm) at ambient temperature, a flow rate of 1.2 mL/min, 50 µL injection volume, and a 7 min run time.

Used Instrumentation

• Agilent 1260 Infinity II HPLC system with G7205C chromatographic module
• ZORBAX SB C-18 column, 4.6×250 mm, 3.5 µm
• Agilent 7850 ICP-MS with MicroMist nebulizer, quartz spray chamber, nickel cones
• Agilent ICP-MS MassHunter software for integrated control and data analysis

Main Results and Discussion

Calibration curves for Hg2+ and MeHg were linear (R² > 0.9999) with background equivalent concentrations near 0.001 µg/L. Both species were fully resolved in under four minutes. Limits of detection were 0.0035 µg/L for Hg2+ and 0.0038 µg/L for MeHg. Spike recoveries in honey (n=9) and milk (n=3 at 0.1–2.0 µg/L) were within 95–103% with RSD < 3%. A 7 h QC run showed RSD < 4% at 0.05 µg/L and < 2.5% at 0.5 µg/L, confirming method precision and instrument stability.

Practical Benefits and Applications

This method delivers rapid, sensitive speciation of Hg in high-matrix food samples, meeting regulatory limits in milk and honey. The integrated HPLC-ICP-MS workflow and software automation support high throughput and routine QA/QC in food safety laboratories.

Future Trends and Opportunities

Further advances may include automated sample preparation, expansion to additional food matrices, coupling with high-resolution mass spectrometry for comprehensive speciation, and application of machine learning for data interpretation and method optimization.

Conclusion

The validated Agilent HPLC-ICP-MS method achieves fast, accurate determination of inorganic Hg and MeHg in milk and honey, with low detection limits and strong reproducibility, ensuring compliance with FSSAI and EU standards for consumer safety.

References

1. World Health Organization. Mercury and Health. WHO Fact Sheet; 2017.
2. Bernhoft RA. Mercury Toxicity and Treatment: A Review of the Literature. Journal of Environmental & Public Health. 2012.
3. European Commission. Mercury in Food. 2021.
4. Food Safety and Standards Authority of India. Maximum Permissible Limits for Metals in Foods. Gazette Notification; August 2020.
5. European Food Safety Authority. Scientific Opinion on Mercury in Food. EFSA Journal. 2012.
6. Food and Agriculture Organization of the United Nations. Gateway to Dairy Production and Products; 2021.
7. Natural Honey Production Statistics. Nation Master; 2019.
8. Dong S, Nelson J, Yamanaka M. Routine Analysis of Fortified Foods using Single Quadrupole ICP-MS. Agilent Technologies; 2019.
9. Agilent Technologies. Handbook of Hyphenated ICP-MS Applications; 2013.
10. Nelson J, Hasty E, Anderson L, Harris M. Determination of Critical Elements in Foods by HPLC-ICP-MS. Agilent Technologies; 2020.
11. Cheng J, High SC. US FDA Elemental Analysis Manual for Methylmercury and Total Mercury in Seafood by HPLC-ICP-MS; 2008.