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IAQ Testing by TO-15

Author:  Earl Christensen

Do you have indoor air quality concerns?  TO-15 may be the answer.  TO-15 analysis is a sensitive and reliable method to identify the cause of odors from unknown sources and to quantify the level of volatile organic compounds (VOC’s) in air in order to compare to known permissible limits.

TO-15 is an EPA method developed to analyze VOC content in ambient air.  This method employs air sampling using a stainless steel cylinder, which has been evacuated so that air can be drawn in and captured.  The captured, whole air sample is then analyzed using state of the art instrumentation which pulls the air from the sampling canister through a series of cryogenic traps.  This concentrates any odor-causing VOC’s in the air so that they can then be identified and quantified using gas chromatography with mass spectrometry (GC/MS). 

While other TO and NIOSH air quality methods require a sampling pump to draw air across a sorbent trap, TO-15 only requires a sampling cylinder; this makes sampling simpler.  The sorbent traps utilized with other TO and NIOSH methods cannot be used for the wide range of compounds the whole air approach of TO-15 can handle.  This is because sorbent tubes collect VOC’s by absorbing the compounds to a chemical media.  This media then has to be chemically or thermally desorbed in order to introduce the sample into an analytical instrument.  Chemical desorption causes an increase in the detection limit due to the use of solvents to remove the chemicals from the sorbent media, which effectively dilutes the sample.  Thermal desorption can cause a breakdown of thermally labile compounds that may be of interest in the air quality assessment, resulting in raised detection limits or complete loss of these compounds during analysis. 

The chemical media used to take an air sample must be considered, as not all media can be used for all VOC’s of interest.  Many situations require the use of specific media for specific compounds, and when an odor-causing compound is unknown, this complicates sampling considerations. 

Better detection limits can be achieved with TO-15 compared to other methods due to limited sample loss, as the entire air sample is introduced into the instrument.  This eliminates the need for sample dilution or loss of compounds from thermal breakdown.  A wide range of compounds can be analyzed using TO-15, which is advantageous when an odor source is unknown.  TO-15 eliminates many of the complications and problems associated with other IAQ testing methods while allowing for lower compound detection limits.

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For more information, contact:
Dr. Kim Baughman, Director of Development
Microbac Laboratories, Inc.
kbaughman@microbac.com

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