High Temperature Headspace Assay of Polymers with Teledyne Tekmar HT3™ Static Headspace Instrument

Significance of the Topic

Indoor air quality in enclosed spaces has become a major concern due to emissions of volatile and semi-volatile compounds from materials. High-temperature polymers used in industrial and consumer products can release VOCs and SVOCs at elevated temperatures. Traditional headspace instruments are limited to 200°C, and thermal desorption requires sample size reduction which may alter results. The Teledyne Tekmar HT3 static headspace instrument extends heating to 300°C and accommodates larger samples, enabling direct analysis of HT polymers.

Objectives and Study Overview

This study aimed to evaluate the performance of the HT3 static headspace instrument at 280°C for detecting VOCs and SVOCs released by HT polymer pellets. The method's sensitivity, linearity, and comparability to existing thermal desorption techniques were assessed using polymer samples of varying mass.

Methodology and Instrumentation

• Sample preparation: raw polymer pellets weighed at 1, 2, 4 and 8 grams into 22 mL headspace vials, sealed with Teflon-lined septa.
• Standard preparation: 100 mg of target VOC in 5 mL methanol, 50 µL aliquot in vial.
• Headspace conditions: HT3 static headspace at 280°C with 30 min equilibration; 12 psig pressurization; 50 mL/min standby flow; 2 min loop fill; 1 min injection.
• GC-FID analysis: Agilent 6890 with Rtx-200 column (30 m x 0.32 mm, 1.5 µm), split ratio 30:1, oven program from 40°C to 320°C, hydrogen and air flows per FID specification.

Main Results and Discussion

Fifteen VOCs and SVOCs were detected across sample sizes. Chromatographic overlays showed a dominant compound (Peak 10) at concentrations up to approximately 19.6 ppm and fourteen additional analytes between 0.01 and 0.29 ppm. All compounds exhibited strong linearity with correlation coefficients above 0.98. The concentration of the major analyte matched values from established thermal desorption methods. The absence of mechanical sample resizing prevented pre-analysis losses and false negatives.

Benefits and Practical Applications of the Method

• High temperature capability (up to 300°C) for polymers with elevated glass transition and melt points.
• Direct analysis of intact pellets up to 11 mm diameter and 60 mm length, avoiding sample alteration.
• Good sensitivity and linearity for a range of VOCs and SVOCs at low ppm levels.
• Streamlined sample preparation with minimal handling, improving throughput and reducing risk of contamination.

Future Trends and Potential Applications

• Integration with mass spectrometry for enhanced compound identification and quantitation.
• Automation of sample loading and data analysis to support high-throughput screening.
• Extension to other polymer types and complex matrices in automotive, packaging, and electronic industries.
• Adoption in regulatory compliance and indoor air quality monitoring standards.

Conclusion

The Teledyne Tekmar HT3 static headspace method at 280°C provides a robust, reproducible approach for analyzing VOC and SVOC emissions from high-temperature polymers. It matches traditional thermal desorption results while offering simpler sample handling and broader temperature range, making it a valuable tool for quality control and environmental safety assessments.

Reference

• Roger Bardsley. High Temperature Headspace Assay of Polymers with Teledyne Tekmar HT3 Static Headspace Instrument. Teledyne Tekmar Application Note, November 2010.