Determination of trace heavy metals in spices using single quadrupole ICP-MS

Significance of the Topic

Spices such as turmeric, black pepper, and chilli are integral to global cuisine and traditional medicine. However, they can accumulate toxic elements from soil, water, and handling processes, posing health risks when residues exceed regulatory limits. Reliable monitoring of trace heavy metals in spices is therefore essential for consumer safety and regulatory compliance.

Objectives and Study Overview

• Evaluate the Thermo Scientific iCAP RQ single quadrupole ICP-MS for simultaneous determination of trace elements in spices.
• Compare method performance with AOAC 2015.01, FSSAI and CFDA guidelines.
• Demonstrate accuracy, precision, detection limits, and robustness across multiple spice matrices.

Methodology

Spice powders were digested in a CEM MARS 6 microwave system using a mixture of nitric acid, hydrogen peroxide, and trace hydrochloric acid, with gold added to mitigate mercury volatility. Digests were diluted to 50 mL, spiked with internal standards (Sc, Ge, In, Rh, Tb, Bi) and analyzed using ICP-MS in kinetic energy discrimination (KED) mode with pure helium to minimize interferences.

Instrumentation Used

• Thermo Scientific iCAP RQ ICP-MS with glass concentric nebulizer and quartz cyclonic spray chamber.
• CEM MARS 6 microwave digestion system.
• Teledyne CETAC ASX 560 autosampler.
• Thermo Scientific Qtegra ISDS software for data acquisition and processing.

Main Results and Discussion

• Calibration linearity was excellent (R² > 0.999) over the studied ranges, with instrument detection limits in low ng·L⁻¹ levels.
• Spiked recoveries in turmeric, black pepper, and chilli powders ranged from 80 to 115% with RSD <10%, meeting AOAC criteria.
• Most native element concentrations were below quantification limits, indicating low contamination levels.
• Internal standard recoveries (80–110%) and continuing calibration verifications remained within acceptance limits over extended sequences, confirming robust performance.

Benefits and Practical Applications of the Method

The developed workflow offers rapid, reliable multielement analysis with minimal sample preparation, reduced reagent consumption and high throughput, suitable for routine quality control in food safety laboratories and regulatory monitoring.

Future Trends and Potential Applications

• Expansion to speciation analyses and nanoparticle detection using advanced ICP-MS techniques.
• Integration of automated sample handling and green digestion protocols to further streamline workflows.
• Application of data analytics and machine learning for pattern recognition and predictive quality assessments.

Conclusion

The combination of microwave-assisted digestion and single quadrupole ICP-MS using the iCAP RQ system provides a robust, sensitive approach for trace heavy metal determination in spices, fulfilling international regulatory requirements and enabling efficient routine testing.

Reference

1. FSSAI Manual for Food Safety, 17th Edition, 2017.
2. China Food and Drug Administration, National Food Safety Standards GB 2762-2017, 2018.
3. Tokalıoğlu Ş et al. Food Anal Methods. 2018;11:2407–2418.
4. Khan N et al. Food Chem. 2014;158:200–206.
5. Briscoe M. J AOAC Int. 2015;98(4):1113–1120.
6. Murugesan S, Oulkar D. Thermo Scientific Application Note 73020, 2019.