Performance Comparison of TDS3 Storage Containers to Swagelok Fittings and Glass Storage Containers

Significance of the Topic

Ensuring the integrity of thermal desorption tubes during storage and transport is essential for reliable air quality measurements.
Contamination or sample loss can lead to inaccurate analytical results and compromise environmental monitoring and compliance efforts.

Objectives and Study Overview

This study evaluates the performance of the TDS3 Thermal Desorption Storage & Sampling System compared to conventional Swagelok PTFE-ferrule end-cap fittings and glass vial storage.
Twelve thermal desorption tubes spiked with a mixture of volatile organic compounds were stored for 14 days under identical low-temperature conditions and subsequently analyzed.

Methodology

Twelve Carbotrap 300 tubes were each spiked with 40 ng of 12 analytes via flash vaporization in a nitrogen stream.
Tubes were divided into three groups:

• Group One: stored in TDS3 polycarbonate containers with Teflon-faced silicone septa
• Group Two: sealed with brass Swagelok end-caps and PTFE ferrules
• Group Three: placed in threaded glass vials sealed with Teflon-faced screw caps

All tubes were collectively stored inside a paint can with activated charcoal at -24 °C for 14 days.
After storage, samples were thermally desorbed and analyzed by gas chromatography.

Instrumentation Used

• TDS3 Thermal Desorption Storage & Sampling System
• Brass Swagelok fittings with PTFE ferrules
• Threaded glass vials with Teflon-faced screw caps
• Carbotrap 300 thermal desorption tubes containing Carbotrap C, Carbotrap B, and Carbosieve S-III
• Flash vaporization apparatus with nitrogen carrier gas
• Paint can and activated charcoal for adsorption during storage
• Laboratory freezer maintained at -24 °C
• Gas chromatograph with thermal desorption interface

Main Results and Discussion

Recovery rates for all three storage systems ranged between approximately 87% and 114%, normalized to internal standards.
TDS3 containers exhibited mean recoveries comparable to Swagelok fittings and glass vials across all tested compounds.
Variability in recovery was similar among the three methods, indicating equivalent sample stability over two weeks.

Benefits and Practical Applications

• Eliminates internal dead volume and minimizes analyte migration during storage
• Reduces risk of tube breakage compared to glass containers
• Simplifies cleaning and reuse by using replaceable septa
• Provides compatibility with common thermal desorption instruments and sampling pumps

Future Trends and Potential Applications

Advancements may include integration of TDS3 containers with automated sampling systems and real-time monitoring devices.
Development of novel adsorbent materials could extend the applicability to a broader range of analytes.
Enhanced compatibility with field-deployable thermal desorption units offers potential for on-site air quality assessments.

Conclusion

The TDS3 storage system delivers sample stability equivalent to traditional Swagelok and glass storage methods while offering operational advantages in handling, reuse, and safety.
Its adoption can streamline thermal desorption workflows in environmental and industrial air monitoring.