Brief Introduction of EPA Method TO-12  

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

Collection

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.

Analysis

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.

Equipment

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

Detection Limits

NMHC: 5.0 ppbv

Advantages

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

Disadvantages

Only total non-methane hydrocarbon concentration can be reported.

Alternatives

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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