Elemental Analysis with Mercury Speciation in Honey Using LC-ICP-MS

Importance of the Topic

Honey is a natural substance valued for its nutrition and flavor but can accumulate both essential and toxic elements. Monitoring heavy metals, especially mercury species, is critical for consumer safety and regulatory compliance.

Objectives and Study Overview

The aim was to establish a rapid, sensitive workflow for simultaneous quantification of essential elements (Cu, Sn, Zn) and toxic metals (As, Cd, Pb, Hg) in honey, and to differentiate inorganic mercury from methylmercury using an LC-ICP-MS system.

Methodology and Instrumentation

• Sample Preparation for Total Elements: 0.5 g honey digested in microwave system with HNO3 and H2O2, diluted to 50 mL.
• Calibration Standards: Multi-element solutions at seven levels (e.g., Hg: 0.5–20 μg/L).
• ICP-MS Conditions: Shimadzu ICPMS-2030 with AS-10 autosampler, RF power 1.2 kW, plasma gas 8 L/min, auxiliary gas 1.1 L/min, carrier gas 0.7 L/min, helium collision gas, TRM software.
• Mercury Speciation: Samples diluted in 0.1 % L-cysteine mobile phase, separated on Synergi Hydro RP column using LC-20Ai, detection by ICPMS-2030.

Main Results and Discussion

• Linearity: Calibration curves for all elements and mercury species showed R² > 0.999.
• Detection Limits: IDLs ranged from 0.003 μg/L (Cd) to 0.5 μg/L (Hg); LOQs in honey were below regulatory thresholds.
• Recovery: Total element spike recoveries at 10 % and 20 % of limits ranged 90–120 % (RSD < 3 %).
• Mercury Speciation: Baseline separation achieved in under 5 min; LOQ of 4 μg/kg with recoveries 94–110 % (RSD < 5 %).

Benefits and Practical Applications

The method delivers fast, accurate multi-element and speciation analysis for routine quality control of honey and other food products, ensuring compliance with FSSAI and international standards while minimizing argon consumption and interference.

Future Trends and Potential Applications

Expected developments include automated sample handling, expansion to diverse food and environmental matrices, advanced software data processing, and adoption of next-generation ICP-MS platforms such as Shimadzu ICPMS-2040 and ICPMS-2050.

Conclusion

The validated HPLC-ICP-MS approach on Shimadzu platforms effectively quantifies trace elements and separates mercury species in honey, supporting food safety monitoring and regulatory adherence. The workflow is adaptable to newer ICP-MS models.

Reference

• World Health Organization Mercury and Health WHO Fact Sheet 2017
• Food Safety and Standards Authority of India Contaminants Toxins and Residues Regulations 2011
• FSSAI Food Safety and Standards Contaminants Toxins and Residues Regulations 2006
• Briscoe M Determination of Heavy Metals in Food by Inductively Coupled Plasma–Mass Spectrometry J AOAC Int 2015 98(4) 1113–1120