Determination of chlorine, bromine, and sulfur in polyethylene materials using combustion IC with a carbonate/bicarbonate eluent

Significance of the topic

Accurate measurement of chlorine, bromine and sulfur in polyethylene is vital for environmental compliance, polymer quality control and safe recycling. These elements are present as flame retardants, stabilizers or contaminant residues and influence product performance and disposal impacts. A rapid, robust analytical approach helps manufacturers and recyclers monitor additive levels and meet regulatory limits.

Objectives and study overview

This work describes the development of an automated combustion ion chromatography method using a carbonate/bicarbonate eluent for simultaneous determination of Cl, Br and S in various polyethylene materials. The approach was validated with a certified reference polymer and applied to four plastic samples to evaluate precision, accuracy and recovery.

Methodology and instrumentation

The procedure combines thermal decomposition and oxidative combustion of polymer samples in the Mitsubishi AQF-2100H system with suppressed-conductivity ion chromatography on a Thermo Scientific Dionex Aquion IC. Key steps include:

• Weighing 20–35 mg of sample in a quartz boat followed by pyrolysis at 900 °C and combustion at 1000 °C in Ar/O₂
• Trapping of HCl, HBr and SO₂ in an aqueous H₂O₂ absorption solution
• Analysis of resulting halide and sulfate ions on a Dionex IonPac AS23 column (4.5 mM Na₂CO₃/0.8 mM NaHCO₃ eluent) with an ERS 500 suppressor

Main results and discussion

Calibration by direct injection of liquid standards achieved linearity up to 1.25 mg/L. Analysis of the ERM EC680K reference material yielded recoveries of 98–100 % and RSD below 2 % for all three analytes. Four plastic samples (LDPE wash bottle, LDPE pipette, PVC-based wrap, bubble wrap) showed chloride levels from trace to tens of mg/L, no detectable bromide and sulfur ranging up to ~60 mg/L in PVC wrap. Spike recovery experiments gave 88–128 % for Cl and 89–96 % for S across samples.

Benefits and practical applications of the method

This CIC protocol offers fully automated sample handling, minimal chemical waste and elimination of time-consuming acid digestions or solvent extractions. It provides reliable routine monitoring of halogens and sulfur in polymer production, waste sorting and recycling streams, supporting quality assurance and regulatory compliance.

Future trends and possibilities

Advances could include faster carbonate columns for reduced analysis time, integration with high-throughput autosamplers, expanded multi-element detection and coupling with data analytics for process optimization. Further miniaturization and adoption of greener absorption chemistries may enhance sustainability and field portability.

Conclusion

The combined Mitsubishi AQF-2100H and Dionex Aquion IC system delivers a precise, accurate and eco-friendly solution for determination of chlorine, bromine and sulfur in polyethylene. The method demonstrated excellent performance on reference materials and real samples, offering laboratories a streamlined alternative for polymer additive analysis.

References

1. Deanin RD. Additives in plastics. Environ Health Perspect. 1975;11:35–39.
2. DIN EN 62321-3-2. Determination of halogens in polymer and electronics by combustion-ion chromatography. 2016.
3. Thermo Fisher Scientific. Application Note 1145: Determination of Halogens in Coal Using Combustion Ion Chromatography. 2016.
4. Thermo Fisher Scientific. Application Note 72349: Determination of Chlorine, Bromine, and Sulfur in Polyethylene Materials Using Combustion Ion Chromatography. 2017.
5. Thermo Fisher Scientific. Technical Note 72211: Combustion Ion Chromatography with a Dionex Integrion HPIC System. 2017.
6. Mitsubishi Chemical Analytech. Operation Manual for NSX-2100 Series Automatic Combustion Unit AQF-2100H.
7. Thermo Fisher Scientific. Dionex IonPac AS22 Fast IC Columns.
8. Thermo Fisher Scientific. Polymers and Plastics Information. Manufacturing and Processing Learning Center.