Thermal decomposition analysis of antioxidant additive by TG-MS - Accurate mass measurement with TG-TOFMS system

Význam tématu

Thermogravimetric analysis (TG) combined with mass spectrometry (MS) provides critical insights into the thermal stability and decomposition pathways of polymer additives. Accurate mass measurement via time-of-flight MS enhances the identification of evolved fragments, supporting quality control, failure analysis, and material design.

Cíle a přehled studie

This work aimed to apply a TG-TOFMS system for qualitative analysis of thermal decomposition products from an antioxidant additive in a fluorocarbon polymer. The study compared conventional electron ionization (EI) with soft photoionization (PI) to improve compound identification.

Použitá metodika

Samples were heated from 50 °C to 650 °C at 10 °C/min under helium flow. The GC interface served as a heated transfer line at 350 °C without chromatographic separation. Evolved gases entered the TOFMS directly, with both EI (70 eV) and PI (D2 lamp, 10.8 eV) ionization modes evaluated.

Použitá instrumentace

• Mass spectrometer: JEOL JMS-T200GC AccuTOF GC high-resolution time-of-flight MS
• Thermogravimeter: NETZSCH STA2500 Regulus TG-DTA
• Interface capillary: 3 m × 0.25 mm I.D., thermostatted at 350 °C
• Carrier gas: helium, 100 mL/min (open-split)

Hlavní výsledky a diskuse

• TG-EI-TOFMS produced a broad TIC peak at ~38 min (350–450 °C), indicating the primary decomposition event.
• EI spectra exhibited extensive fragmentation, complicating direct identification of decomposition products.
• PI spectra simplified the mass profile, revealing three dominant ions at m/z 166, 222, and 278.
• Accurate mass analysis assigned formulas C9H10O3, C13H18O3, and C17H26O3 (all DBE = 5), suggesting core antioxidant structures.
• Extracted ion chromatograms showed that higher-mass fragments (m/z 278) evolved at lower temperatures (~382 °C), whereas lower-mass species (m/z 166) peaked at higher temperatures (~421 °C), indicating sequential breakdown.

Přínosy a praktické využití

• Soft PI with high-resolution TOFMS enables clear molecular ion detection for complex polymer additives.
• Direct TG-MS coupling accelerates thermal stability screening without the need for chromatographic separation.
• Insights into degradation pathways inform additive design, material processing, and quality assurance in polymer manufacturing.

Budoucí trendy a možnosti využití

• Integration of tandem MS and alternative soft ionization methods for deeper structural characterization.
• Hyphenation with chromatographic or spectroscopic techniques for comprehensive profiling.
• Application to real-time monitoring of polymer processing and recycling streams.
• Development of miniaturized TG-MS systems for field analysis and process control.

Závěr

TG-TOFMS with soft photoionization effectively elucidates the thermal decomposition behavior of antioxidant additives in polymers. Accurate mass measurement simplifies fragment identification and reveals sequential degradation steps, establishing this approach as a powerful tool for analytical characterization and material development.