Brief Introduction of ASTM Method 1945, 1946  

Use for fixed gases, methane and light hydrocarbon testing.


The sample is collected in a precleaned and evacuated SUMMA canister or in a Tedlar bag using a pump. Composite sample 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/TCD/FID. The combined GC/TCD will measure both fixed gases (such as oxygen, nitrogen, carbon monoxide and carbon dioxide) and methane. Light hydrocarbons, including C1-C7, are analyzed by GC/FID. Both fractions may be analyzed by direct injection of a small amount of the sample into the GC.


Canisters, Tedlar bags, GC/TCD/FID

Detection Limits

Fixed Gases: 0.5%
Light Hydrocarbons (C1-C6): 1.0 ppmv


Small sample volume required. Analysis is fast.


Low detection limits can not be achieved from GC/TCD.


TO-14 modified, EPA 25, TO-3 modified

Representatives Uses

Ambient air surveys, landfill well gas surveys, manufacture emission gas surveys, indoor air, stack gas analysis.

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