Brief Introduction of EPA Method TO-12  

Use for the determination of total non-methane hydrocarbons in air (NMHC) as methane.


Samples are collected by precleaned and evacuated SUMMA canister or in a Tedlar bag using a pump. Composite samples may be collected using time-integrated sampling. Sample volume ranges from 1 to 20 liters. Ambient sampling will not be affected by humidity or rain.


The sample is analyzed by GC/FID with a cryogenic focus trap packed with glass beads. The sample is introduced into a cryogenic trap in which all hydrocarbons are trapped except methane. The trapped hydrocarbons are then thermally desorbed and introduced directly into the FID detector for quantification.


Canisters, Tedlar bags, GC/FID, Cryogenic trap, etc.

Detection Limits

NMHC: 5.0 ppbv


A very low detection limit can be achieved because a large amount of sample can be passed through the cryogenic trap.


Only total non-methane hydrocarbon concentration can be reported.


TO-14 modified, ASTM 1945, TO-3 modified

Representatives Uses

Landfill well gas surveys, ambient air surveys, manufacture emission gas surveys, indoor air, stack gas analysis.


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