Radiello® Passive Samplers and Vapor Intrusion

Significance of Passive VOC Sampling

Passive sampling has become an essential approach for assessing vapor intrusion of volatile organic compounds (VOCs) in soil gas and indoor air. Compared to active methods such as Summa canisters (EPA TO-15) or pump-driven sorbent tubes (EPA TO-13, TO-17), passive devices offer low maintenance, simple deployment and retrieval, and achieve low detection limits. These features make passive samplers particularly useful for field studies, long-term monitoring, and scenarios where power or infrastructure is limited.

Study Objectives and Overview

The article presents Radiello® radial diffusive samplers (RAD130 for solvent desorption and RAD145 for thermal desorption) and compares their performance to traditional axial badge-type samplers. Key aims include:

• Characterizing sampling rates and detection limits for common VOCs.
• Evaluating the effect of airflow and environmental conditions on sampling performance.
• Demonstrating practical deployment times for both short-term (STEL) and time-weighted average (TWA) applications.

Methodology and Instrumentation

Radiello passive samplers consist of a diffusive body surrounding a sorbent cartridge. Two configurations are described:

• RAD130 VOC/BTEX by Solvent Desorption (white diffusive body, RAD120)
• RAD145 VOC/BTEX by Thermal Desorption (yellow diffusive body, RAD1202)

Sampling performance was quantified under air velocities of 0.1–10 m/s and relative humidity of 15–90 %. Sampling rates (Q) for benzene ranged up to 80 mL/min for RAD130, compared to less than 10 mL/min for conventional axial samplers. Exposure durations studied included 15 min to 8 h indoors and up to 30 days outdoors (solvent desorption) or 7–14 days (thermal desorption).

Main Results and Discussion

Key findings include:

• Radiello samplers exhibit sampling rates 2–5 times higher than badge-type axial samplers across a suite of VOCs (benzene, toluene, PCE, TCE, xylenes, etc.).
• Limits of detection range from 0.01–0.10 μg/m³ for most compounds with thermal desorption and 0.05–1.0 μg/m³ for solvent desorption, depending on laboratory protocols.
• High cartridge loading capacity (~80 mg VOCs) allows sampling of up to 3,000–3,500 μg/m³ over an 8-hour deployment or up to 70,000–80,000 mg/m³ over 14 days.
• Performance remains consistent across typical environmental conditions, with minimal starved-diffusion effects at low flow velocities.

Benefits and Practical Applications

Radiello passive samplers support a wide variety of field applications:

• STEL measurements over minutes to hours and TWA averages over multiple days or weeks.
• Indoor and outdoor air monitoring, crawl spaces, sub-slab soil gas sampling, and vapor intrusion screening.
• Broad compound coverage including BTEX, chlorinated solvents, MTBE and semi-volatile species when coupled with different cartridges.
• High throughput field deployment with minimal logistical overhead and no power requirements.

Future Trends and Opportunities

Emerging developments aim to expand passive sampling capabilities and data integration:

• New sorbent materials for improved selectivity and sensitivity to emerging contaminants.
• Miniaturized diffusion bodies for discreet indoor monitoring and microbiome studies.
• Integration with wireless sensors for real-time environmental condition logging.
• Standardization across laboratories to harmonize detection limits and sampling rates.

Conclusion

Radiello radial diffusive samplers offer a robust, high-capacity passive sampling solution for VOC vapor intrusion and air monitoring. Their superior sampling rates, low detection limits, and flexible deployment durations make them a versatile tool for environmental scientists, industrial hygiene professionals, and regulatory studies.

Použitá instrumentace

Key components:

• RAD130 VOC/BTEX by Solvent Desorption (white diffusive body, RAD120)
• RAD145 VOC/BTEX by Thermal Desorption (yellow diffusive body, RAD1202)
• Cartridge adsorbents, support plates, vertical adapters and calibration kits

Reference

1. Shamory B., Hayes H., Mahfood J., Schultz K. Radiello Passive Sampling Method for Evaluating Vapor Intrusion. Business of the Brownfields Conference 2009, Pittsburgh, PA.
2. SKC Technical Note. Measuring Sub-ppb Levels of VOCs in Indoor Air. Publication 1720 Rev 1103.
3. Ultra III: The Creative Evolution of Indoor Air and Ambient Sampling. SKC Publication 1804, Issue 1104.