ICP-OES Analysis of Titanium Dioxide in Foods Prepared with a One-Step Digestion

Significance of the Topic

Titanium dioxide (TiO2) is extensively used as a whitening agent in foods, cosmetics, and pharmaceuticals. Recent concerns over TiO2 nanoparticles’ potential genotoxicity led to its ban as food additive E171 in the EU. Reliable analytical methods are required to detect TiO2 in diverse food matrices at low concentrations, ensuring compliance with emerging safety regulations.

Objectives and Study Overview

This study aimed to develop a robust, one-step acid digestion procedure without hydrofluoric acid, coupled with the Agilent 5800 Vertical Dual View (VDV) ICP-OES, to quantify TiO2 and other trace elements in complex food samples. Four representative food products—confectionery, decorative spray, salad cream, and a protein bar—were selected to validate the workflow.

Methodology and Instrumentation

Food samples (500 mg) were digested in a Mars 6 microwave system with 9 mL H2SO4 and 1 mL H2O2 at 250 °C for 1 h. Digests were diluted to 50 mL, centrifuged, and analyzed by ICP-OES. Calibration standards were matrix-matched (18 % H2SO4, 2 % H2O2). Smart software tools—IntelliQuant Screening for semiquantitative element profiling, Intelligent Rinse for optimized wash steps, and Outlier Conditional Formatting (OCF) for real-time QC alerts—ensured data integrity and throughput.

Used Instrumentation

• Agilent 5800 VDV ICP-OES with SPS 4 autosampler
• SeaSpray glass concentric nebulizer
• Double-pass cyclonic spray chamber
• Easy-fit semi-demountable VDV torch (1.8 mm ID)
• ICP Expert Pro software with FBC and FACT background correction

Key Results and Discussion

Limits of detection (LOD) and quantification (LOQ) for Ti and other elements were below Chinese regulatory criteria (GB 5009.268-2016). Certified reference materials (NIST 1566b Oyster Tissue, NIES No. 9 Sargasso) and spike-recovery tests yielded recoveries within ±10 %. Comparative analysis using HF digestion and ICP-MS demonstrated excellent agreement. A 10-hour stability test showed <1.4 % RSD for all elements, confirming instrument robustness.

Benefits and Practical Applications

• Eliminates hazardous HF, simplifying and enhancing lab safety
• Achieves low detection limits suitable for regulatory compliance
• Smart software tools streamline method development and QC
• High throughput with minimized carry-over through Intelligent Rinse

Future Trends and Possibilities

Integration of AI-driven method optimization, expansion to nanoparticle speciation, and adaptation to other challenging matrices (e.g., dairy, pharmaceuticals) will further advance TiO2 analysis. Miniaturized digestion systems and enhanced detection techniques may enable real-time monitoring of additives in production lines.

Conclusion

The combination of a one-step H2SO4/H2O2 microwave digestion and the Agilent 5800 VDV ICP-OES, supported by advanced software tools, provides a safe, accurate, and high-throughput workflow for quantifying TiO2 and trace elements in foods. This approach addresses regulatory demands and promotes consumer safety.

References

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