Analysis of Iodate Ion and Iodide Ion

Significance of Topic

Accurate determination of iodate (IO3–) and iodide (I–) ions is critical in environmental monitoring, food quality control, and pharmaceutical analysis. These halogen species play key roles in nutritional assessments, water treatment processes, and industrial quality assurance. Ion chromatography (IC) offers a selective, sensitive, and reliable approach for separating and quantifying these anions in complex matrices.

Objectives and Study Overview

This application note demonstrates a robust IC method using the Shim-pack IC-SA2 column for simultaneous analysis of iodate and iodide. Key goals include achieving baseline resolution, optimizing run time, and ensuring reproducibility under standardized conditions.

Methodology and Instrumentation

The separation was carried out on a Prominence™ HIC-SP system equipped with:

• Analytical column: Shim-pack IC-SA2, 250 mm × 4.0 mm I.D.
• Guard column: Shim-pack IC-SA2(G), 10 mm × 4.6 mm I.D.
• Eluent: 2.5 mmol/L sodium carbonate + 1.7 mmol/L sodium hydrogen carbonate
• Flow rate: 1.5 mL/min
• Column temperature: 30 °C
• Injection volume: 5 µL
• Detection: UV at 210 nm for IO3– and 225 nm for I– (SPD-20AV detector)

Main Results and Discussion

The chromatogram exhibits two well-resolved peaks corresponding to iodate and iodide. Under the chosen conditions, iodate elutes at approximately 2.0 minutes and iodide at about 7.5 minutes. Peak symmetry is excellent with stable baselines and no coelution, confirming the method’s specificity. Dual-wavelength detection enhances selectivity, allowing independent monitoring of each analyte at its optimal absorption maximum.

Benefits and Practical Applications

This IC method offers:

• High resolution and reproducibility for routine ion analysis.
• Rapid run times suitable for high-throughput laboratories.
• Minimal sample preparation, reducing analysis costs and complexity.
• Applicability across water quality testing, food iodine fortification checks, and pharmaceutical quality control.

Future Trends and Opportunities

Advances in column technology and detector sensitivity will further reduce analysis time and detection limits. Integration with automated sample handling and data processing systems will streamline workflows. Emerging applications include speciation of halogen oxyanions in environmental forensics and inline monitoring in manufacturing processes.

Conclusion

The Shim-pack IC-SA2 method provides a reliable and efficient approach for the simultaneous determination of iodate and iodide ions. Its robustness, speed, and selectivity make it highly suited for diverse analytical settings.

Reference

Shimadzu Corporation. ERAS-1000-0368, First Edition: Sep. 2022.