A New Approach to Whole Air Sampling using Deactivated Glass Bottles

Significance of the Topic

Whole air sampling is a cornerstone technique in environmental and industrial monitoring, enabling comprehensive analysis of volatile organic compounds (VOCs) in air without preconcentration. Traditional methods rely on stainless steel canisters or adsorbent tubes, but cost, sample stability, and analyte recovery challenges limit their broader application. The development of cost-effective, inert sampling media can expand monitoring capabilities for regulatory compliance, indoor air quality, and source emission studies.

Objectives and Study Overview

This study evaluates a new deactivated glass container, the Bottle-Vac™ sampler, as an alternative to Tedlar bags and Silonite-coated stainless steel canisters for EPA Methods TO-14A and TO-15 whole air sampling. Key goals include:

• Comparing analyte recovery and holding times across sampling media.
• Assessing reproducibility and inertness for aromatic, halogenated, and oxygenated VOCs at high (1 ppm) and low (10 ppb) concentrations.
• Demonstrating the practical advantages and limitations of Bottle-Vac samplers for field and laboratory use.

Methodology and Instrumentation

Sampling media tested:

• 16 oz Bottle-Vac™ samplers with Micro-QT valves
• 0.6 L Silonite™ MiniCans (stainless steel)
• 1 L Tedlar™ bags

High-level source testing used a 1 ppm TO-14 standard containing 39 aromatic and halogenated compounds. Low-level testing employed a 10 ppb TO-15 standard of 64 diverse VOCs. Samples were held for up to 5 days at room temperature and for extended periods at elevated temperature (60 °C).

Used Instrumentation

• Autosamplers: Entech 7032AQ-L with 7100A Preconcentrator; Entech 7500 Robotic Autosampler with heating oven and Extended Cold Trap Dehydration.
• GC-MS: Agilent 6890 gas chromatograph coupled to 5973N mass selective detector; DB-1 column (0.32 mm ID, 60 m, 1 µm).

Main Results and Discussion

Source-level recoveries after 3 days for Tedlar bags and after 5 days for Bottle-Vac and Silonite Canisters show:

• Silonite canisters achieved ~100 % recovery for all TO-14 analytes over 5 days.
• Bottle-Vac samplers closely matched canister performance, with negligible loss across the VOC range.
• Tedlar bags exhibited significant losses, especially for heavier compounds, even within their 3 day holding limit.

Low-level TO-15 testing revealed that preheating Bottle-Vac samplers to 60 °C before analysis improved recovery of polar, water-soluble compounds (e.g., formaldehyde recovery increased from 42 % to 83 %). Long-term stability over 30 days demonstrated acceptable recoveries for all TO-15 compounds in both Bottle-Vac and Silonite canisters, far exceeding Tedlar bag capabilities.

Benefits and Practical Applications

Advantages of Bottle-Vac samplers include:

• Cost effective: 4–5× the price of Tedlar bags versus 20–50× for canisters.
• Reusable and easy to clean: rapid evacuation and humidified nitrogen cycles achieve sub-ppb cleanliness.
• No field calibration or pumps required for grab or time-weighted sampling.
• Flexible analysis: ability to split or re-analyze sample aliquots, and to thermally desorb any fraction.
• Enhanced analyte range with preheating to recover heavier and polar VOCs.

These features suit applications ranging from indoor air quality and mold VOC monitoring to source emission surveys and laboratory-based dilutions.

Future Trends and Potential Applications

Advancements may include:

• Field validation for vapor intrusion and trace-level TO-15 regulatory monitoring.
• Integration with automated sample preparation robots and IoT-enabled vacuum control.
• Expansion of glass container sizes and valve materials to optimize for specific compound classes.
• Coupling with improved preconcentration techniques for ultra-trace analysis.

Conclusion

Bottle-Vac samplers offer stainless steel canister–equivalent performance in a lower-cost, glass-based format. They outperform Tedlar bags in analyte recovery and stability, while avoiding the high expense of Silonite canisters. Their ease of cleaning, flexible sampling modes, and compatibility with heated preconcentration make them a promising tool for broad analytical chemistry applications.