Brief Introduction of EPA Method TO-4

Use for organo-chlorine pesticides and PCBs, adaptable to other classes of pesticides and other semi-volatile organic compounds.


Samples are collected by drawing a very large measured volume of air through a modified high volume sampler (HiVol) containing a glass fiber filter and a large polyurethane foam (PUF) cartridge. Smaller cartridges of similar or different types may be used. If they are, however, the method would best be described by a different number (see Alternatives).


Determined by Soxhlet extraction followed by Kuderna-Danish concentration of the extract, subsequent separation of the sample components from one another by GC and identification/qualification by electron capture detector (GC/ECD). If modified for other target compounds, other detectors, including GC/MS, may be employed.


Cartridges and filters plus one for QC, HiVol sampler, flow meter, PUF holder, special shipping container. Projects may also require on-site measurement of temperature, relative humidity, barometric pressure (absolute), wind direction and speed.

Detection Limits

Detection limits – 1.0 ppbv levels (sub-parts per trillion)


At very low levels, sampling equipment is generally available to companies providing air sampling services. Can use same extract to determine a variety of target compound classes.


PUF cartridges are bulky, require an oversized extractor and are easily contaminated as well as difficult to clean. Don't often need such low detection limits. Note: GD Air Testing, Inc. has an oversized extractor, the technology, and the experience to clean the cartridges.


TO-10 plus some NIOSH methods

Representatives Uses

Stack gases from incinerators, fence line monitoring during remediation, and remediation around personnel.

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