Determination of chlorate and perchlorate in milk using ion chromatography-mass spectrometry

Importance of the Topic

Milk can be contaminated by chlorate from chlorinated water and cleaning agents, and by perchlorate as an environmental contaminant. These oxychlorine species may interfere with iodine uptake, posing health risks especially to infants and young children.

Objectives and Study Overview

The primary goal was to establish a robust ion chromatography–mass spectrometry (IC-MS) method for quantifying chlorate and perchlorate in milk. This application uses the Thermo Scientific Integrion HPIC system and ISQ EC single quadrupole MS for selective, sensitive analysis.

Methodology and Instrumentation

Samples were diluted with 0.02% NaOH and subjected to centrifugal ultrafiltration. Separation was achieved on a Dionex IonPac AS20 column with an electrolytically generated KOH gradient. A six-port divert valve directed the suppressed eluate to MS detection. Mass spectrometric analysis employed negative-mode ESI in SIM mode for monoisotopic and M+2 isotopes.

• Integrion HPIC system with EGC 500 KOH eluent generator and CR-ATC trap column
• Dionex IonPac AG20 guard and AS20 analytical columns
• ISQ EC single quadrupole mass spectrometer (ESI negative mode)
• Dionex ADRS 600 dynamic suppressor and AXP auxiliary pump

Main Results and Discussion

Calibration was linear from 0.1 to 10 µg/L for both analytes (r² > 0.9998). Limits of quantification reached 0.1 µg/L for chlorate and perchlorate. Recoveries in spiked milk ranged from 88.9% to 109% (RSD < 3%). Precision over eight injections gave RSDs ≤ 3.3%. Isotope ratio confirmation met regulatory criteria (± 25%). Column performance remained stable after > 900 injections.

Benefits and Practical Applications

The method omits laborious solid-phase extraction, relying on simple dilution and filtration. IC-MS provides high selectivity in complex matrices, suitable for regulatory compliance and routine QA/QC in dairy analysis.

Future Trends and Potential Uses

Expected developments include extending the approach to other food and environmental samples, integrating autosampling for higher throughput, leveraging high-resolution MS for multi-residue screening, and supporting real-time monitoring in processing lines.

Conclusion

The presented IC-MS protocol offers a reliable, sensitive, and precise solution for chlorate and perchlorate determination in milk, aligning with stringent regulatory requirements and ensuring consumer safety.

References

1. Alomirah HF, et al. Food Addit Contam Part A. 2016;33:1016–1025.
2. McCarthy WP, et al. Compr Rev Food Sci Food Saf. 2018;17:1561–1575.
3. National Nuclear Data Center. Chart of the Nuclides, 17th Ed. 2010. ISBN 9780984365319.
4. Thermo Fisher Scientific. Application Update 72507. 2020.
5. European Commission. Decision 2002/657/EC. 2002.
6. US EPA. Method 332.0. 2005.