Combustion Ion Chromatography

Importance of the Topic

Combustible materials such as polymers, fuels, environmental samples and electronic components often contain trace halogens and sulfur species that can cause corrosion, catalyse toxin formation and harm the environment. Reliable quantification of these elements is critical for quality control, regulatory compliance and environmental monitoring. Combustion Ion Chromatography (CIC) provides a fully automated, high throughput approach for simultaneous determination of halogens (chloride, bromide, fluoride, iodide) and sulfur in diverse matrices without manual digestion steps.

Objectives and Overview

This study introduces the Metrohm CIC system that integrates combustion digestion and ion chromatography into a single automated workflow. The main goals are to assess its performance in terms of accuracy, precision, sample throughput and compliance with international standards such as RoHS, WEEE, ASTM, UOP and EU/National norms.

Methodology and Instrumentation

Samples undergo pyrohydrolysis in an argon atmosphere, where oxygen and water convert halogens and sulfur into gaseous acids. These compounds are trapped in an absorber module and mixed into a liquid phase for direct injection into the IC. Key components include:

• Combustion module (Trace Elemental Instruments) with quartz or ceramic tubes for different sample aggressiveness
• 920 Absorber Module for efficient gas capture, water dosing, oxidant elimination and rinsing
• 930 Compact IC Flex system with conductivity detection and MagIC Net software control
• Metrohm intelligent Partial Loop Injection Technique (MiPT) enabling automated calibration with a single multi-ion standard
• Automated sampling modules: Solid Autosampler, Liquid Autosampler and GLS Sampler for gaseous or LPG samples with safety features such as automatic inlet locking and leak detection

Main Results and Discussion

Validation with certified reference materials (polyethylene pellets ERM-EC681k, coal NIST 2682b) demonstrated recoveries within 96–103 % for chloride, bromide and sulfur. Chromatograms show clear baseline separation of halide peaks within 14–20 min. The precision and accuracy surpass offline digestion methods, and the system reliably enforces regulatory limits for halogen and sulfur content across environmental, polymer, fuel and electronic matrices.

Benefits and Practical Applications

• Extends ion chromatography to solid, liquid and gaseous samples without manual digestion
• Simultaneous quantification of multiple halogens and sulfur with high sensitivity
• High throughput (up to 60 solid samples or continuous liquid/gas streams) and minimal footprint
• Ideal for compliance testing under RoHS, WEEE, DIN EN 228, IEC 60502-1 and relevant ASTM/UOP standards
• Automated calibration and sample handling reduce labor and potential errors

Future Trends and Opportunities

The trend towards green analytical methods and stricter environmental regulations will drive demand for robust automated systems like CIC. Advances in miniaturized IC detectors, improved membrane materials for absorption and AI-driven process optimization could further enhance sensitivity, reduce analysis time and enable in situ monitoring of industrial emissions and complex sample streams.

Conclusion

Combustion Ion Chromatography consolidates sample digestion, gas absorption and ion analysis into one automated platform, delivering precise, accurate and high-throughput determination of halogens and sulfur. Its adaptability to various matrices and compliance with international standards make CIC a valuable tool in quality assurance, environmental analysis and industrial process monitoring.

Reference

• ASTM D7359-14: Standard Test Method for Total Fluorine, Chlorine and Sulfur in Aromatic Hydrocarbons and their Mixtures by Oxidative Pyrohydrolytic Combustion followed by Ion Chromatography Detection
• ASTM D8247: Standard Test Method for Determination of Total Fluorine and Total Chlorine in Coal by Oxidative Pyrohydrolytic Combustion Followed by Ion Chromatography Detection
• ASTM D7994-17: Standard Test Method for Total Fluorine, Chlorine, and Sulfur in Liquid Petroleum Gas (LPG) by Oxidative Pyrohydrolytic Combustion Followed by Ion Chromatography Detection
• UOP 991-13: Chloride, Fluoride, and Bromide in Liquid Organics by Combustion Ion Chromatography (CIC)
• RoHS, WEEE, DIN EN 228, IEC 60502-1 compliance guidelines