Accurate and reliable analysis of food samples using ICP-MS

Importance of the Topic

Ensuring food safety and compliance with global regulations demands accurate, sensitive, and high‐throughput analytical methods to quantify both essential nutrients and trace toxic elements in diverse food and beverage matrices.

Objectives and Study Overview

This work aimed to develop and validate a single ICP-MS method combined with direct argon gas dilution (AGD) for the simultaneous analysis of major and ultra‐trace elements across a broad range of food and beverage samples, delivering robust, reproducible, and maintenance‐free operation over extended sequences.

Methodology and Instrumentation

Sample groups comprised carbohydrates and protein‐rich foods, vegetables and fruits, spices, milk and high‐fat products, and beverages. Solid samples underwent closed‐vessel microwave digestion, while beverages were degassed and diluted 10×. Calibration employed six concentration levels prepared in 2% HNO₃, internal standards (Sc, Y, Rh, Lu, Tl with 4% IPA for beverages), and certified reference materials (CRMs). Argon gas dilution at 55% of maximum flow was optimized to mitigate matrix effects without compromising detection limits.

Instrumentation Used

Thermo Scientific iCAP RQ ICP-MS with:

• Borosilicate glass MicroMist nebulizer (400 μL/min) and cooled quartz cyclonic spray chamber (2.7 °C)
• Nickel sampler/skimmer cones with high‐matrix insert
• Collision/reaction cell (CRC) using helium at 4.3 mL/min and 3 V KED
• Autotuned lens settings, dwell times 0.05–0.2 s, five sweeps per mass

Main Results and Discussion

• Linear dynamic range covered 0.005 µg/kg (Hg) to 600 000 µg/kg (Na), with R² > 0.9996 for critical analytes.
• Instrument detection limits (IDL), limits of quantification (LOQ), and method LOQs (MLOQ) remained well below regulatory maximum levels globally.
• Internal standard recoveries stayed between 85 % and 110 % over an 11.5 h uninterrupted run spanning diverse sample groups.
• CRM recoveries for major elements ranged from 90 % to 115 %, and for toxic elements (As, Cd, Pb, Hg) from 91 % to 109 % across multiple days.
• No performance deterioration or maintenance was required over nine consecutive days, analyzing a total of 1878 samples (~240 samples/day) with single‐block calibration and periodic quality checks.

Benefits and Practical Applications

• High throughput workflow with minimal user intervention and no cleaning or maintenance between long sequences.
• Simultaneous quantification of both nutrition‐relevant and toxic elements in one analytical run.
• Robustness against diverse matrix compositions, ensuring reliable data for regulatory compliance, quality control, and research laboratories.

Future Trends and Applications

• Automation of sample introduction and data processing to further increase laboratory throughput.
• Extension of the AGD‐ICP-MS approach to emerging contaminants, isotopic ratio measurements, and speciation analysis.
• Implementation in real‐time monitoring and process control settings within food production environments.

Conclusion

The optimized ICP-MS method with direct argon gas dilution delivers a highly sensitive, accurate, and maintenance‐free solution for comprehensive elemental analysis in food and beverages, supporting regulatory compliance and high‐volume testing demands.

References

1. Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs.
2. GB-2762-2017 National Food Safety Standard for Maximum Levels of Contaminants in Foods, China.