Pyrolysis and GC×GC-MS. A hot topic!

Význam tématu

Comprehensive two-dimensional gas chromatography coupled with mass spectrometry (GC×GC-MS) after pyrolysis offers unparalleled separation power and detailed chemical profiling of complex polymer materials. This approach is critical for quality control, recycling process optimization and studying environmental degradation of plastics.

Cíle a přehled studie / článku

This workshop presentation by Robert Cody at MDCW 2025 describes the laboratory setup, analytical workflow and case studies demonstrating how pyrolysis GC×GC-MS can identify polymer composition, detect additives and monitor oxidation products. The goal is to showcase both the instrumentation and AI-augmented data analysis tools that enhance compound identification and data interpretation.

Použitá instrumentace

The laboratory platform includes:

• JEOL AccuTOF GC-Alpha with interchangeable ion sources (EI/CI/PI, EI/FI/FD) and direct insertion probe
• Agilent 8890 GC system
• Frontier Lab EGA/PY-3030D multi-shot pyrolyzer
• HTA 2800T autosampler for liquids, headspace and SPME
• SepSolve thermal modulator for GC×GC-MS

Software tools for data acquisition and interpretation:

• ChromSpace for thermal modulator control
• AnalyzerPro XD for deconvolution-based peak detection and batch comparison
• GC Image for advanced GC×GC data visualization
• msFineAnalysis AI for integrated EI, accurate-mass, retention index and soft-ionization analysis with a 130-million-compound AI database

Hlavní výsledky a diskuse

Case study 1: A commercially labeled PLA bag was shown by pyrolysis profiling to be polyethylene. GC×GC-TOFMS revealed hundreds of hydrocarbon species. Key assignments included C11–C13 aromatics, alkanes (e.g., tridecane), alkenes and cycloalkanes. GC×GC resolution uncovered low-abundance isomers masked in 1D GC.

Case study 2: Oxidized low-density polyethylene (LDPE) samples exhibited ketones, aldehydes and trace carboxylic acids. Acid number titration (16 mg KOH/g) correlated with the abundance of oxygenated compounds. Selective ion channel chromatograms (SICC) for characteristic fragments allowed confident identification of acids despite low peak intensities.

Demonstration of msFineAnalysis AI showed integrated assignment of 8-nonene-2-one by combining EI and CI spectra, isotope fit, retention index matching and database correlation, significantly improving confidence in peak identification.

Přínosy a praktické využití metody

Pyrolysis GC×GC-MS enables rapid screening of polymer composition for anti-counterfeiting, process monitoring in pyrolysis-based recycling, additive analysis in quality control and assessment of environmental degradation pathways. The high peak capacity and soft-ionization options facilitate structural elucidation of oxidation products and emerging contaminants.

Budoucí trendy a možnosti využití

Future developments include expanded AI-driven spectral libraries for pyrolysates, routine implementation of negative-ion electron capture for carboxylic acid detection, real-time coupling with pilot-scale pyrolysis reactors and integration of ambient ionization techniques. Advances in data processing will further reduce manual interpretation and enhance throughput.

Závěr

Pyrolysis GC×GC-MS combined with high-resolution TOF mass spectrometry and AI-enhanced software provides deep chemical insight into polymer materials. While complete identification of all peaks remains a challenge, the methodology reliably differentiates polymer types, tracks oxidation and supports applications in recycling, materials development and environmental analysis.

Reference

1. Zhao D., Wang X., Miller J.B., Huber G.W. The Chemistry and Kinetics of Polyethylene Pyrolysis: A Process to Produce Fuels and Chemicals. ChemSusChem. 13, 1764–1774 (2020).