Volatile organic compounds (VOCs) represent a critical category of air pollutants, monitored in industrial, urban, and indoor environments to assess their impact on health and the environment.
The choice between canister sampling and sorbent tubes depends on the characteristics of the target compounds and the specific analytical needs.
To ensure accurate monitoring, several international standard methods have been developed, including:
US EPA TO-17: Active Sampling on Absorbent Tubes for VOCs in Ambient AirUS
EPA TO-15/TO-14: SUMMA Canister Collection and GC-MS AnalysisASTM
D-6196-03: Procedures for Sorbent Selection and Thermal DesorptionASTM
D-5466: Standard Method for VOCs in Atmosphere Using Canisters
ISO EN 16017: Active/Diffusion Sampling with Absorbent Tubes and TD-GC Analysis
ISO EN 16000-6: Determination of VOCs in Indoor Air with Tenax TA and TD-GC-MS/FID.
Canisters: Ideal for Ultra-Volatile Compounds
Canisters are particularly suitable for highly volatile and non-polar compounds, such as: Light hydrocarbons (C2), volatile Freons (CF4, C2F6) and compounds stable in ambient air.
Advantages:
✔ Excellent long-term storage
✔ Ideal for rapid sampling
✔ No risk of adsorption on internal surfaces
✔ Validated for methods such as EPA TO-15
Limitations:
✖ Less effective for polar or reactive compounds
✖ Not suitable for long-term sampling (TWA)
Absorbent Tubes: Versatile and Convenient
Absorbent tubes are the best choice for less volatile compounds (C3 to n-C30), including: Alcohols, ketones, esters, aldehydes, Aromatics and halocarbons, and Combustible gases and odor profiles.
Advantages:
✔ Supported by international standards (ISO 16017, ASTM D6196, EN ISO 16000)
✔ Suitable for active and diffusive sampling
✔ High sensitivity (from ppt to percentage levels)
✔ Reusable and easy to clean
✔ Ideal for personal monitoring and TWA
✔ Reanalysis with Markes systems (recollect function)
Limitations:
✖ Not suitable for ultra-light compounds (e.g., C2)
Conclusions
The choice between canisters and sorbent tubes depends on the nature of the VOCs being monitored:
Canisters: Optimal solution for ultravolatile compounds (EPA method TO-15).
Absorbent tubes: Versatile, economical, and ideal for less volatile compounds and extended sampling periods.
Both technologies offer accuracy and regulatory compliance, but the best approach varies by application.
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