TOPAS / TDS D – Badge-Type Thermodesorption Passive Sampler Based on Tenax for Air Sampling - Development Study

Importance of the topic

Accurate monitoring of volatile organic compounds (VOCs) in indoor environments and workplaces is critical for assessing air quality, regulatory compliance, and protecting human health. Traditional passive badge samplers require solvent extraction and long exposure times, which can introduce errors and limit sampling throughput. Combining passive diffusion sampling with direct thermal desorption simplifies workflows, reduces contamination risk, and enables shorter monitoring periods.

Objectives and study overview

This development study evaluated the prototype TOPAS/TDS D badge-type passive sampler, which integrates a spiral-groove Tenax sorbent badge with thermal desorption transfer to gas chromatography–mass spectrometry (GC–MS). Key goals were to:

1. Evaluate thermal desorption recoveries for representative non-polar and polar VOCs.
2. Determine badge sampling rates for various analytes.
3. Compare passive sampling performance with active Tenax tube sampling in a controlled emission chamber using rubber flooring.

Methodology

Thermal desorption recoveries were assessed by spiking 200 ng and 1,000 ng of standard mixtures onto the Tenax layer of TOPAS badges and desorbing at 250 °C. Peak areas were compared to direct liquid injections into the cooled injection system. For sampling rate determination, a 500 L emission test chamber (22 °C, 50 % RH, 0.5 air changes/h) housed glued rubber flooring. Passive badges were exposed for 5 h, while active samples were collected in parallel on Tenax tubes (5–10 L at 100 mL/min).

Instrumentation used

• Gerstel TDS 2 thermal desorption injector with cooled injection system (CIS)
• Agilent 6890 GC coupled to 5973 MS detector
• Agilent HP-624 capillary column (30 m × 0.25 mm ID × 1.4 µm film)
• Custom badge holder with Teflon membrane sealing interface

Main results and discussion

• Non-polar VOC recoveries exceeded 80%, largely independent of loading level; polar analytes (glycol derivatives, phenoxyethanol) showed lower recoveries (<70%).
• Sampling rates ranged from 0.5 to 2.6 L/h for targeted compounds, comparable to active sampling values.
• Chromatographic profiles from passive and active samples were identical, confirming comprehensive analyte uptake by the badge.
• A 5 h passive exposure provided sufficient mass for GC–MS identification and quantitation down to ~0.5 µg/m³.

Benefits and practical applications

• Eliminates solvent extraction and manual preparation, lowering contamination risk and labor time.
• Short sampling times enable same-day indoor air quality assessments and expert appraisals.
• High sampling rates support low-level VOC monitoring in occupational and environmental settings.
• Compact, pump-free design allows easy shipping and deployment for personal dosimetry and field surveys.

Future trends and potential applications

Further refinements may include automated badge exchange systems and enhanced sorbent-membrane combinations to improve polar analyte recovery. The integration of passive sampling with thermal desorption shows promise for widespread adoption in routine environmental monitoring, industrial hygiene, and forensic air analysis.

Conclusion

The TOPAS/TDS D badge-type sampler effectively merges passive diffusion uptake with direct thermal desorption GC–MS analysis. It achieves rapid VOC enrichment and reliable quantitation comparable to active sampling, while eliminating solvent extraction steps. Ongoing development will focus on user-friendly handling and extending the analyte range.