Halogens in polymer by Combustion Ion Chromatography

Significance of the Topic

Polymers applied in building and decoration require flame retardancy to meet safety standards. Incorporating halogenated flame retardants enhances their resistance to ignition. Determining the precise halogen content ensures regulatory compliance, product performance, and environmental safety.

Objectives and Study Overview

This study demonstrates the application of Combustion Ion Chromatography (Combustion IC) to quantify fluorine, chlorine, bromine, sulfur, and iodine in a technical polymer sample. A certified reference material (CRM EC680K) verifies system recovery over the complete analytical workflow.

Methodology and Instrumentation

A 20–50 mg polymer sample is accurately weighed into a quartz combustion boat, covered with quartz fleece, and analyzed using Combustion IC equipped with flame sensor technology and intelligent Partial Loop Injection Technique (MiPT). Key combustion parameters include:

• Carrier gas: Ar at 100 mL/min
• Oxidant gas: O₂ at 300 mL/min
• Oven temperature: 1050 °C
• Post-combustion time: 300 s
• Initial absorption solution volume: 2.0 mL

Analytical parameters:

• Flow rate: 0.7 mL/min
• Injection volume: 200 µL (MiPT)
• Recording time: 35 min
• Column temperature: 32 °C

The system employs a Metrohm 930 Compact IC Flex platform with conductivity detection after sequential suppression. Separation utilizes a series of Metrosep suppression and trap columns. Eluent is 3.2 mmol/L sodium carbonate with 1.0 mmol/L sodium hydrogen carbonate; suppressor regenerant is 100 mmol/L sulfuric acid. Absorber solution contains 100 mg/L H₂O₂.

Main Results and Discussion

Analysis of the technical polymer yielded the following halogen concentrations (n=3):

• Fluorine: 524 mg/kg (RSD 3.6 %)
• Chlorine: 3.2 mg/kg (RSD 4.8 %; recovery 94 % ±1.8 %)
• Bromine: 1.4 mg/kg (RSD 4.2 %; recovery 100 % ±2.3 %)
• Sulfur: not quantified
• Iodine: not detected

Non‐integrated peaks included nitrite, nitrate, and phosphate. The recovery study with CRM EC680K confirms robustness and accuracy of the method for chlorine and bromine.

Benefits and Practical Applications

The Combustion IC approach enables simultaneous determination of multiple halogens in solid polymer matrices with high sensitivity and precision. It supports:

• Quality control of flame‐retardant additives
• Regulatory compliance for building materials
• Environmental monitoring of halogen release

Future Trends and Potential Applications

Advancements may include integration of automated sample introduction, enhanced detection sensitivity for trace iodine and sulfur species, and expansion to complex polymer blends. Coupling with mass spectrometric detection could offer structural insights into halogenated compounds.

Conclusion

Combustion Ion Chromatography provides a reliable, precise, and sensitive method to quantify halogens in polymers. Its validated performance supports flame‐retardant evaluation and regulatory testing in industrial and research laboratories.

Reference

1. Metrohm. IC Application Note CIC–027. Version 1, September 2018.