Ensuring toy safety from hexavalent chromium to meet European regulations using IC-ICPMS quantification

Significance of the topic

Younger children readily ingest or mouth small toy parts, increasing the risk of exposure to leachable toxic metals. Hexavalent chromium (Cr(VI)) is a recognized carcinogen and is tightly regulated under European standard EN 71-3:2019 at a maximum migration limit of 0.005 mg/kg. Accurate, low-level speciation of Cr(VI) in toy extracts is essential for consumer safety and regulatory compliance.

Study objectives and overview

This work aimed to refine an existing ion chromatography–ICP-MS method to ensure reliable Cr(VI) quantification in liquid, sticky, and scraped toy materials according to EN 71-3:2019. The primary goals were to lower the quantification limit to 0.0025 mg/kg, accelerate analysis, and maintain method robustness.

Methodology

• Migration extraction: simulated gastric fluid at pH 7.5 maintained Cr(VI) stability during contact with toy materials.
• Chromatographic separation: 75 mM HNO₃ eluent (pH 7.0), flow 0.7 mL/min, ambient-to-40 °C column compartment, polymer-based guard (NG-1) and analytical (AG-7) columns, and 100 µL injection volume.
• ICP-MS detection: 52Cr isotope monitored in KED mode with helium collision gas to remove polyatomic interferences.

Used instrumentation

• Thermo Scientific Dionex ICS-6000 Ion Chromatography System with guard columns NG-1 and AG-7.
• Thermo Scientific iCAP RQ ICP-MS fitted with a PFA-LC nebulizer and Qtegra ISDS software featuring tQuant quantification.
• Thermo Scientific AS-AP autosampler; UltiMate 3000 thermostatted column compartment; IC/LC connector kit.

Main results and discussion

• Calibration was linear (R² = 0.9998) over 0.02–0.16 µg/L, achieving an instrumental detection limit of 0.35 ng/L (3σ).
• Analysis runtime reduced to 2 min per sample (versus 3 min recommended), enhancing throughput.
• No native Cr(VI) detected in glue, paint, or toy extracts; spiked recoveries ranged 98–109%, confirming accuracy and absence of carry-over.
• Strict control of extraction/ injection pH and column temperature ensured retention time stability (~50 s).

Benefits and practical applications of the method

• Exceeds current EN 71-3:2019 requirements by quantifying down to 0.0025 mg/kg Cr(VI).
• High-throughput, 2-minute analyses support routine QA/QC in toy safety testing laboratories.
• Speciation capability distinguishes Cr(VI) from other oxidation states, crucial for health risk assessment.

Future trends and potential applications

• Regular reassessment of speciation protocols to achieve ever lower detection limits.
• Integration of automated sample preparation for fully hands-free workflows.
• Application to additional consumer goods and environmental samples requiring trace chromium speciation.
• Development of microfluidic IC systems and novel column chemistries to further reduce runtime and solvent usage.

Conclusion

The optimized IC-ICP-MS method, combining the Thermo Scientific ICS-6000 and iCAP RQ systems, delivers rapid, robust, and ultrasensitive quantification of Cr(VI) in toy materials, ensuring compliance with EN 71-3:2019 and readiness for future regulatory tightening.

References

1. EN 71-3:2019. Safety of Toys – Part 3: Migration of certain elements.
2. Alvarez CC, Gómez MEB, Zavala AH (2021). Hexavalent chromium: Regulation and health effects. Journal of Trace Elements in Medicine and Biology, Article 126729.
3. Thermo Fisher Scientific (2021). Application Note 43175: Quantification of Cr(VI) in toys by IC-ICP-MS.