Quantitative Analysis of Chromium and Arsenic Species in Food and Food Packaging using LC-ICPMS

Importance of the Topic

Speciation of trace elements in food and packaging materials has become essential to ensure consumer safety, as different chemical forms of elements like chromium and arsenic exhibit distinct toxicological profiles. Regulatory frameworks within the EU, such as the farm-to-fork principle and packaging waste ordinances, mandate precise identification and quantification of harmful species beyond total element concentrations.

Objectives and Study Overview

The primary goal of this work is to validate a combined liquid chromatography–inductively coupled plasma mass spectrometry (LC-ICPMS) approach for:

• Determination of hexavalent chromium in food packaging materials following EU VerpackV limits.
• Speciation of inorganic and organic arsenic species in rice, in compliance with EU maximum levels for foodstuffs.

Methodology and Instrumentation

The analytical workflow integrates a Shimadzu ICPMS-2030 mass spectrometer with a Prominence Inert LC system. Key instrument parameters include:

• ICPMS operating at 1.2 kW RF power, with total argon consumption below 10 L/min and low purity requirements (Argon 3.5).
• Collision cell using helium at flow rates between 4.4 and 6.0 mL/min to reduce polyatomic interferences.
• LC separation for chromium on a Hamilton PRP-X100 column (250 × 4.1 mm, 10 µm) using 30 mM ammonium nitrate (pH 7.1).
• LC separation for arsenic on a Shiseido CapcellPak C18 MG S5 column with an ion-pair mobile phase (10 mM sodium 1-butanesulfonate, 4 mM tetramethylammonium hydroxide, 4 mM malonic acid, 0.05 % methanol, pH 3).
• Sample injection volumes: 495 µL for chromium and 20 µL for arsenic species.

Main Results and Discussion

• Chromium speciation achieved excellent calibration linearity (r > 0.9999) and detection in the low ppt range, enabling reliable quantification of Cr(III) and Cr(VI) in packaging extracts.
• Chromium VI levels were determined well below the 100 mg/kg limit for packaging materials, demonstrating compliance with the EU VerpackV.
• Arsenic speciation in white and brown rice completed within five minutes, separating As(III), As(V), and dimethylarsenic acid (DMAA) effectively.
• Analysis of certified reference materials yielded inorganic arsenic recoveries within 98 ± 2 % and agreement with certified values: 0.085 mg/kg in white rice and 0.302 mg/kg in brown rice.

Benefits and Practical Applications

The combined LC-ICPMS platform offers:

• Streamlined method development and routine operation in a single software environment.
• Robust sensitivity and selectivity for trace speciation in complex food matrices.
• Full compliance with EU regulatory requirements for food safety and packaging materials.

Future Trends and Applications

• Extension of speciation protocols to additional elements and matrices, such as mercury and tin species in seafood.
• Integration with high-resolution mass spectrometry for comprehensive non-target screening of emerging contaminants.
• Automation and miniaturization of sample preparation to enhance throughput and reduce solvent consumption.
• Data-driven risk assessment using speciation profiles to inform regulatory standards and public health policies.

Conclusion

LC-ICPMS represents a powerful and reliable analytical technique for the speciation of toxic elements in food and packaging. The demonstrated methods achieve high sensitivity, regulatory compliance, and operational efficiency, supporting improved food safety monitoring and risk assessment.

References

• [1] Lab Manager 2017, gluten-free diet may increase risk of arsenic, mercury exposure.
• [2] EU Verpackungsordnung (VerpackV) on Packaging Waste, 2014.
• [3] Ricepedia 2017, global staple rice consumers.
• [4] Commission Regulation (EU) 2015/1006 on maximum inorganic arsenic levels in foodstuffs.