Simultaneous Iodine and Bromine Speciation Analysis of Infant Formula by HPLC-ICP-MS

Importance of the topic

Speciation of iodine and bromine in infant formula is critical because the bioavailability of iodine and the toxicity of bromine depend on their chemical forms. Accurate determination of iodide, iodate, bromide and bromate helps assess nutritional value and safety in products designed for early development.

Objectives and summary of the study

This study presents a rapid method to simultaneously separate and quantify four halogen species in milk-based infant formulas in under 6.5 minutes using HPLC coupled with ICP-QQQ. Four commercial powder samples and a standard reference material were analyzed to validate method performance and demonstrate real-world applicability.

Methodology and instrumentation

Sample preparation included:

• Total bromine determination by microwave digestion of about 0.2 g sample in nitric acid followed by dilution.
• Speciation analysis and total iodine by water bath extraction at 50 °C, filtration, and direct injection.

An Agilent 1260 Infinity II LC system equipped with an anion exchange column was coupled to an Agilent 8900 Triple Quadrupole ICP-MS in single quadrupole mode with helium cell gas. The mobile phase was a phosphate–sulfate–EDTA buffer at pH 7.0 flowing at 1 mL/min. Key instrument settings delivered baseline separation of four species.

Main results and discussion

Calibration curves for iodide, iodate, bromide and bromate showed excellent linearity (r² ≥ 0.9999) from 0 to 100 ppb. Signal-to-noise detection limits ranged from 0.07 to 0.67 ppb. In the NIST 1849a reference material, measured total iodine (1.33 mg/kg) and iodide agreed within 103% recovery of certified values; no iodate or bromate was detected. Analysis of four infant formulas revealed only iodide and bromide, with total iodine levels between 1 232 and 2 592 µg/kg (25.9–54.5 µg/100 kcal). Recoveries of iodide and bromide relative to total element were 87–102% and 85–100%, confirming method accuracy. Spike recovery tests at 20 and 40 ppb levels yielded recoveries of 96–100% and good repeatability for multiple injections.

Benefits and practical applications

• Rapid simultaneous speciation of four halogen species in a single run.
• High sensitivity with sub-ppb detection limits suitable for regulatory compliance.
• Robust performance for both total element and speciation analysis in complex food matrices.
• Applicable to quality control, nutritional assessment, and safety monitoring in infant nutrition products.

Future trends and opportunities

Emerging directions include integration of single quadrupole ICP-MS platforms for cost efficiency, expansion to other food matrices, automation of sample preparation, coupling with complementary separation techniques, development of non-targeted speciation workflows, and adoption of microfluidic or field-deployable systems for rapid on-site analysis.

Conclusion

Anion exchange HPLC coupled with ICP-QQQ enables fast, accurate, and sensitive simultaneous analysis of iodide, iodate, bromide and bromate in infant formula. The method meets regulatory requirements and provides valuable insight into nutrient bioavailability and contaminant risk. Its robust performance supports routine use in research and industrial laboratories.

References

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• US FDA Code of Federal Regulations Title 21 Part 107 Infant Formula 2018
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