Analysis of additives in plastic by thermal desorption (TD) GC-TOFMS - accurate mass measurement and isotope pattern matching

Importance of the topic

Plastic additives such as antioxidants and flame retardants play a critical role in determining polymer properties, product stability and safety. Rapid and reliable identification of these compounds is essential for quality control, regulatory compliance and material performance assessment.

Objectives and study overview

This study aimed to demonstrate the use of thermal desorption GC-TOFMS with accurate mass measurement and isotope pattern matching to detect and identify additives extracted directly from plastic samples.

Methodology

A small amount of plastic (0.4 mg) was subjected to thermal desorption with a ramp from 150 to 350 °C. Desorbed components were separated by gas chromatography on a DB1-HT column and analyzed by time-of-flight mass spectrometry with electron ionization at 70 eV. Spectra were recorded over m/z 35–1400 at 0.4 second intervals.

Used Instrumentation

• Thermal desorption system: PY-2020iD (Frontier Laboratories)
• Gas chromatograph: 6890N (Agilent) with DB1-HT, 8 m × 0.25 mm × 0.1 μm column
• Mass spectrometer: JMS-T100GCV AccuTOF GCv (JEOL) in EI+ mode
• Data analysis software: Mass Spec Tools™ (ChemSW)

Main results and discussion

The total ion chromatogram revealed several known additives including squalene, decabromodiphenyl ethane and the antioxidant Irganox® 1330. An unknown peak adjacent to Irganox® 1330 was detected. Comparison of fragmentation patterns suggested structural similarity. Accurate mass measurement and isotope pattern matching reduced 21 elemental composition candidates to four, with C50H70O3 showing the best match. The unknown was identified as an Irganox® 1330 analog lacking one t-butyl group.

Benefits and practical applications

• Fast and direct analysis of additives without solvent extraction
• High mass accuracy and isotope matching improve identification confidence
• Suitable for routine quality control and forensic analysis of polymers

Future trends and applications

Integration with advanced chemometric tools and expanded high-resolution libraries could further enhance detection of trace additives. Coupling with complementary detectors may support broader characterization of polymer formulations.

Conclusion

Thermal desorption GC-TOFMS with accurate mass measurement and isotope pattern matching provides a robust approach for identifying plastic additives, enabling detailed compositional analysis with high confidence.