Combustion Ion Chromatography

Importance of the Topic

The accurate determination of halogens and sulfur in diverse materials is critical across environmental monitoring, quality control in manufacturing, and regulatory compliance (e.g., RoHS, WEEE). Traditional offline digestion methods can be slow, labor-intensive, and prone to contamination. Combustion Ion Chromatography (CIC) offers a fully automated route to simultaneously quantify multiple halogens and sulfur with high precision, broad applicability, and streamlined workflows.

Objectives and Study Overview

This application note presents the Metrohm CIC system, which integrates combustion digestion (pyrohydrolysis) and ion chromatography into a single automated platform. It aims to demonstrate the system’s capacity for reliable, simultaneous analysis of halogens (fluoride, chloride, bromide, iodide) and sulfur across solid, liquid, and gaseous matrices, benchmarked against certified reference materials.

Methodology and Instrumentation

Samples undergo pyrohydrolysis in an oxygen/argon atmosphere at elevated temperature. Generated gaseous analyte species are trapped in an absorption solution within the 920 Absorber Module. The absorbed ions are then separated and detected by ion chromatography (Compact IC Flex with conductivity detector). Automated sample introduction is handled by the MMS 5000 autosampler, which accommodates solids and liquids with rapid kit exchange. Key automation features include a flame sensor for optimal combustion control, Metrohm intelligent Partial Loop Injection Technique (MiPT) for single-standard calibration, and MagIC Net software for full system control and data management.

Main Results and Discussion

Analysis of certified polyethylene pellets and coal reference material achieved recoveries within 95–105% for chloride, bromide, and sulfur. Chromatograms exhibit baseline separation of target ions within a 20 min run time. Precision (RSD) is typically below 2%. The system handles high-pressure gas samples (LPG/GSS module) with Peltier-cooled dosing and heated vaporization for complete transfer.

Benefits and Practical Applications

• Broad matrix compatibility: solids, liquids, gases
• Simultaneous multi-ion determination with separate quantification
• High throughput: automated digestion and injection
• Superior precision and trueness versus offline methods
• Compliance with FDA, GLP, ASTM, UOP, and other norms
• No internal standard required in absorption solution

Future Trends and Potential Applications

Future developments may include coupling CIC with mass spectrometry for enhanced sensitivity, miniaturizing combustion modules for field deployment, and integrating real-time process monitoring in industrial settings. Expansion of automated workflows to additional elements (e.g., phosphorus, nitrogen) and advanced data analytics will further broaden CIC’s utility.

Conclusion

The Metrohm CIC system delivers a robust, automated solution for comprehensive halogen and sulfur analysis across diverse sample types. Its combination of pyrohydrolysis, absorber module, and ion chromatography achieves high accuracy, compliance with standards, and significant labor savings compared to traditional digestion methods.

References

No literature references were provided in the original text.